--- 1/draft-ietf-mpls-cr-ldp-00.txt 2006-02-05 00:37:35.000000000 +0100 +++ 2/draft-ietf-mpls-cr-ldp-01.txt 2006-02-05 00:37:35.000000000 +0100 @@ -1,1329 +1,1612 @@ -MPLS Working Group L. Andersson, A. Fredette, B. Jamoussi +MPLS Working Group Bilel Jamoussi, Editor Internet Draft Nortel Networks -Expiration Date: July 1999 - R. Callon - IronBridge Networks - - P. Doolan - Ennovate Networks - - N. Feldman - IBM Corp - - E. Gray - Lucent Technologies - - J. Halpern - Newbridge Networks - - J. Heinanen - Telia Finland - - T. E. Kilty - Northchurch Communications - - A. G. Malis - Ascend Communications, Inc. - - M. Girish - SBC Technology Resources, Inc. - - K. Sundell - Ericsson - - P. Vaananen - Nokia Telecommunications - - T. Worster - General DataComm, Inc. - - L. Wu, R. Dantu - Alcatel +Expiration Date: August 1999 - January 1998 + February 1999 Constraint-Based LSP Setup using LDP - draft-ietf-mpls-cr-ldp-00.txt + draft-ietf-mpls-cr-ldp-01.txt Status of this Memo - This document is an Internet-Draft. Internet-Drafts are working - -CR-LDP Specification - 2 - Exp. Apr 1999 + This document is an Internet-Draft and is in full conformance with + all provisions of Section 10 of RFC2026. - documents of the Internet Engineering Task Force (IETF), its areas, - and its working groups. Note that other groups may also distribute - working documents as Internet-Drafts. + Internet-Drafts are working documents of the Internet Engineering + Task Force (IETF), its areas, and its working groups. Note that + other groups may also distribute working documents as Internet- + Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." - To learn the current status of any Internet-Draft, please check the - "1id-abstracts.txt" listing contained in the Internet-Drafts Shadow - Directories on ftp.is.co.za (Africa), nic.nordu.net (Europe), - munnari.oz.au (Pacific Rim), ftp.ietf.org (US East Coast), or - ftp.isi.edu (US West Coast). + The list of current Internet-Drafts can be accessed at + http://www.ietf.org/ietf/1id-abstracts.txt + + The list of Internet-Draft Shadow Directories can be accessed at + http://www.ietf.org/shadow.html. + + Distribution of this memo is unlimited. + +Copyright Notice + + Copyright (C) The Internet Society (1998). All Rights Reserved. Abstract Label Distribution Protocol (LDP) is defined in [LDP] for distribution of labels inside one MPLS domain. One of the most important services that may be offered using MPLS in general and LDP in particular is support for constraint-based routing of traffic across the routed network. Constraint-based routing offers the opportunity to extend the information used to setup paths beyond what is available for the routing protocol. For instance, an LSP can be - setup based on an explicit route constraint, a Service Class (SC) - constraint, or both. Constraint-based routing (CR) and Traffic - Engineering requirements have been proposed by [FRAME], [ARCH] and - [TER]. These requirements may be met by extending LDP for support of - constraint-based routed label switched paths (CRLSPs). Other uses - exist for CRLSPs as well ([VPN1] and [VPN2]). + setup based on explicit route constraints, QoS constraints, and + others. Constraint-based routing (CR) is a mechanism used to meet + Traffic Engineering requirements that have been proposed by [FRAME], + [ARCH] and [TER]. These requirements may be met by extending LDP for + support of constraint-based routed label switched paths (CRLSPs). + +CR-LDP Specification - 2 - Exp. August 1999 + + Other uses exist for CRLSPs as well ([VPN1], [VPN2] and [VPN3]). This draft specifies mechanisms and TLVs for support of CRLSPs using LDP. The Explicit Route object and procedures are extracted from [ER]. +Table of Contents + + 1. Introduction ......................................... 3 + 2. Constraint-based Routing Overview .................... 3 + 2.1 Strict and Loose Explicit Routes ..................... 4 + 2.2 Traffic Characteristics .............................. 4 + 2.3 Pre-emption .......................................... 5 + 2.4 Route Pinning ........................................ 5 + 2.5 Resource Class ....................................... 5 + 3. Solution Overview .................................... 5 + 3.1 Required Messages and TLVs ........................... 7 + 3.2 Label Request Message ................................ 7 + 3.3 Label Mapping Message ................................ 8 + 3.4 Notification Message ................................. 9 + 3.5 Release & Withdraw Messages .......................... 9 + 4. Protocol Specification .............................. 9 + 4.1 Explicit Route TLV (ER-TLV) ......................... 10 + 4.2 Explicit Route Hop TLV .............................. 10 + 4.3 Traffic Parameters TLV .............................. 12 + 4.3.1 Semantics ........................................... 13 + 4.3.1.1 Frequency ........................................... 13 + 4.3.1.2 Peak Rate ........................................... 14 + 4.3.1.3 Committed Rate ...................................... 14 + 4.3.1.4 Excess Burst Size .................................... 14 + 4.3.1.5 Peak Rate Token Bucket................................ 14 + 4.3.1.6 Committed Data Rate Token Bucket ..................... 15 + 4.3.1.7 Weight ......................... ..................... 16 + 4.3.2 Procedures ........................................... 16 + 4.3.2.1 Label Request Message ................................ 16 + 4.3.2.2 Label Mapping Message ................................ 16 + 4.3.2.3 Notification Message ................................. 17 + 4.4 Preemption TLV ....................................... 18 + 4.5 LSPID TLV ........................................... 18 + 4.6 Resource Class TLV .................................. 19 + 4.7 ER-Hop Semantics ..................................... 19 + 4.7.1 ER-Hop 1 TLV IPv4 Prefix ............................. 20 + 4.7.2 ER-Hop 2 TLV IPv6 Prefix ............................. 20 + 4.7.3 ER-Hop 3 TLV AS Number ............................... 21 + 4.7.4 ER-Hop 4 TLV LSPID ................................... 21 + 4.8 Processing of the ER-TLV ............................. 22 + 4.8.1 Selection of the next hop ............................ 22 + 4.8.2 Adding the Label Request Message to the next hop ..... 24 + 4.9 Route Pinning TLV ................................... 24 + 4.10 CR-LSP FEC Element ................................... 24 + 4.11 Error Subcodes ...................................... 25 + +CR-LDP Specification - 3 - Exp. August 1999 + + 5. Security Considerations .............................. 26 + 6. Acknowledgement ...................................... 26 + 7. References ........................................... 26 + 8. Author Information ................................... 28 + + Appendix A CRLSP Establishment Examples ......................... 30 + A.1 Strict Explicit Route Example ........................ 30 + A.2 Node Groups and Specific Nodes Example ............... 31 + + Appendix B QoS Service Examples ................................. 34 + B.1 Service Examples ..................................... 34 + B.2 Establishing CR-LSP Supporting Real-Time Applications. 35 + B.3 Establishing CR-LSP Delay Insensitive Applications ... 36 + 1. Introduction The need for constraint-based routing (CR) in MPLS has been explored elsewhere [ARCH], [FRAME], and [TER]. Explicit routing is a subset of the more general constraint-based routing function. At the MPLS WG meeting held during the Washington IETF there was consensus that LDP should support explicit routing of LSPs with provision for indication - of associated (forwarding) priority. In the Chicago meeting, the + of associated (forwarding) priority. In the Chicago meeting, a decision was made that support for explicit path setup in LDP will be - moved to a separate document. This document provides that support. We - propose an end-to-end setup mechanism of a constraint-based routed - LSP (CRLSP) initiated by the ingress LSR. We also specify mechanisms - to provide means for reservation of resources for the explicitly - routed LSP. - - We introduce TLVs and procedures that provide support for: + moved to a separate document. This document provides that support and + it has been accepted as a working document in the Orlando meeting. + This specification proposes an end-to-end setup mechanism of a + constraint-based routed LSP (CRLSP) initiated by the ingress LSR. We + also specify mechanisms to provide means for reservation of resources + using LDP. -CR-LDP Specification - 3 - Exp. Apr 1999 + This document introduce TLVs and procedures that provide support for: - Strict and Loose Explicit Routing - - Specification of Service Class - Specification of Traffic Parameters - Route Pinning - - CRLSP bumping though setup/holding priority + - CRLSP Pre-emption though setup/holding priorities - Handling Failures + - LSPID + - Resource Class -2. CRLSP Overview + Section 2 introduces the various constraints defined in this + specification. Section 3 outlines the CR-LDP solution. Section 4 + defines the TLVs and procedures used to setup constraint-based routed + label switched paths. Appendix A provides several examples of CR-LSP + path setup. Appendix B provides Service Definition Examples. - CRLSP over LDP Specification is designed with several goals in mind: +2. Constraint-based Routing Overview + + Constraint-based routing is a mechanism that supports the Traffic + Engineering requirements defined in [TER]. Explicit Routing is a + subset of the more general constraint-based routing where the + +CR-LDP Specification - 4 - Exp. August 1999 + + constraint is the explicit route (ER). Other constraints are defined + to provide a network operator with control over the path taken by an + LSP. This section is an overview of the various constraints supported + by this specification. + +2.1 Strict and Loose Explicit Routes + + Like any other LSP an CRLSP is a path through an MPLS network. The + difference is that while other paths are setup solely based on + information in routing tables or from a management system, the + constraint-based route is calculated at one point at the edge of + network based on criteria, including but not limited to routing + information. The intention is that this functionality shall give + desired special characteristics to the LSP in order to better support + the traffic sent over the LSP. The reason for setting up CRLSPs, + might be that one wants to assign certain bandwidth or other Service + Class characteristics to the LSP, or that one wants to make sure that + alternative routes use physically separate paths through the network. + + An explicit route is represented in a Label Request Message as a + list of nodes or groups of nodes along the constraint-based route. + When the CRLSP is established, all or a subset of the nodes in a + group may be traversed by the LSP. Certain operations to be + performed along the path can also be encoded in the constraint-based + route. + + The capability to specify, in addition to specified nodes, groups of + nodes, of which a subset will be traversed by the CRLSP, allows the + system a significant amount of local flexibility in fulfilling a + request for a constraint-based route. This allows the generator of + the constraint-based route to have some degree of imperfect + information about the details of the path. + + The constraint-based route is encoded as a series of ER-Hops + contained in a constraint-based route TLV. Each ER-Hop may identify + a group of nodes in the constraint-based route. A constraint-based + route is then a path including all of the identified groups of nodes. + + To simplify the discussion, we call each group of nodes an abstract + node. Thus, we can also say that a constraint-based route is a path + including all of the abstract nodes, with the specified operations + occurring along that path. + +2.2 Traffic Characteristics + + The traffic characteristics of a path are described in the Traffic + Parameters TLV in terms of a peak rate, committed rate, and service + granularity. The peak and committed rates describe the bandwidth + constraints of a path while the service granularity can be used to + specify a constraint on the delay variation that the CRLDP MPLS + domain may introduce to a path's traffic. + +CR-LDP Specification - 5 - Exp. August 1999 + +2.3 Pre-emption + + CR-LDP signals the resources required by a path on each hop of the + route. If a route with sufficient resources can not be found, + existing paths may be rerouted to reallocate resources to the new + path. This is the process of path pre-emption. Setup and holding + priorities are used to rank existing paths (holding priority) and the + new path (setup priority) to determine if the new path can pre-empt + an existing path. + + The setupPriority of a new CRLSP and the holdingPriority attributes + of the existing CRLSP are used to specify priorities. Signaling a + higher holding priority expresses that the path, once it has been + established, should have a lower chance of being pre-empted. + Signaling a higher setup priority expresses the expectation that, in + the case that resource are unavailable, the path is more likely to + pre-empt other paths. The exact rules determining bumping are an + aspect of network policy. + + The allocation of setup and holding priority values to paths is an + aspect of network policy. + + The setup and holding priority values range from zero (0) to seven + (7). The value zero (0) is the priority assigned to the most + important path. It is referred to as the highest priority. Seven (7) + is the priority for the least important path. The use of default + priority values is an aspect of network policy. + + The setupPriority of a CRLSP should not be higher (numerically less) + than its holdingPriority since it might bump an LSP and be bumped by + next "equivalent" request. + +2.4 Route Pinning + + Route pinning is applicable to segments of an LSP that are loosely + routed - i.e. those segments which are specified with a next hop with + the 'L' bit set or where the next hop is an "abstract node". A CRLSP + may be setup using route pinning if it is undesirable to change the + path used by an LSP because a better next hop becomes available at + some LSR along the loosely routed portion of the LSP. + +2.5 Resource Class + + Network resources may be classified in various ways by the network + operator. These classes are also known as "colors" or "administrative + groups". When an CR-LSP is being established, it's necessary to + indicate which resource classes the CR-LSP can draw from. + +3. Solution Overview + + CRLSP over LDP Specification is designed with the following goals: + +CR-LDP Specification - 6 - Exp. August 1999 1. Meet the requirements outlined in [TER] for performing traffic engineering and provide a solid foundation for performing more - general constrain-based routing. + general constraint-based routing. 2. Build on already specified functionality that meets the requirements whenever possible. Hence, this specifications is based on [LDP] and the Explicit Route object and procedures defined in [ER]. - 3. Keep the solution simple and tractable. + 3. Keep the solution simple. In this document, support for unidirectional point-to-point CRLSPs is specified. Support for point-to-multipoint, multipoint-to-point, is for further study (FFS). - Support for explicitly routed LSPs in this specification depends on - the following minimal LDP behaviors as specified in [LDP]: + Support for constraint-based routed LSPs in this specification + depends on the following minimal LDP behaviors as specified in [LDP]: - Basic and/or Extended Discovery Mechanisms. - Use the Label Request Message defined in [LDP] in downstream on demand label advertisement mode with ordered control. - Use the Label Mapping Message defined in [LDP] in downstream on demand mode with ordered control. - Use the Notification Message defined in [LDP]. - Use the Withdraw and Release Messages defined in [LDP]. - - Loop detection (in the case of loosely routed segments of a - CRLSP) mechanisms. + - Use the Loop Detection (in the case of loosely routed segments + of a CRLSP) mechanisms defined in [LDP]. In addition, the following functionality is added to what's defined in [LDP]: - - The Label Request Message used to setup a CRLSP includes a CR- - TLV based on the path vector defined in [ER] and specified in - Section 4 of this document. - -CR-LDP Specification - 4 - Exp. Apr 1999 - - - An LSR implicitly infers ordered control from the existence of a - CR-TLV in the Label Request Message. This means that the LSR can - still be configured for independent control for LSPs established - as a result of dynamic routing. However, when a Label Request - Message includes a CR TLV, then ordered control is used to setup - the CRLSP. Note that this is also true for the loosely routed - parts of a CRLSP. + - The Label Request Message used to setup a CRLSP includes one or + more CR-TLVs defined in Section 4. For instance, the Label Request + Message may include the ER-TLV. - - Traffic Parameters TLVs may optionally be carried in the Label - Request Message to specify the CRLSP traffic characteristics. + - An LSR implicitly infers ordered control from the existence of + one or more CR-TLVs in the Label Request Message. This means that + the LSR can still be configured for independent control for LSPs + established as a result of dynamic routing. However, when a Label + Request Message includes one or more of the CR-TLVs, then ordered + control is used to setup the CRLSP. Note that this is also true + for the loosely routed parts of a CRLSP. - New status codes are defined to handle error notification for failure of established paths specified in the CR-TLV. +CR-LDP Specification - 7 - Exp. August 1999 + Examples of CRLSP establishment are given in Appendix A to illustrate how the mechanisms described in this draft work. -3. Required Messages and TLVs +3.1 Required Messages and TLVs Any Messages, TLVs, and procedures not defined explicitly in this - document are defined in the [LDP] Specification. The following - subsections are meant as a cross reference to the [LDP] document and - indication of additional functionality beyond what's defined in [LDP] - where necessary. + document are defined in the [LDP] Specification. The state + transitions which relate to CR-LDP messages can be found in [LDP- + STATE]. -3.1 Label Request Message + The following subsections are meant as a cross reference to the [LDP] + document and indication of additional functionality beyond what's + defined in [LDP] where necessary. + +3.2 Label Request Message The Label Request Message is as defined in 3.5.8 of [LDP] with the - following modifications (required only if the CR-TLV is included in - the Label Request Message): + following modifications (required only if any of the CR-TLVs is + included in the Label Request Message): - Only a single FEC-TLV may be included in the Label Request - Message. + Message. The CR-LSP FEC TLV should be used. - - The Optional Parameters TLV includes the definition of the - Constraint-based TLV specified in Section 4 and the Traffic - Parameters TLV specified in Section 5. + - The Return Message ID TLV is MANDATORY. - - The Procedures to handle the Label Request are augmented by the - procedures for processing of the CR-TLV as defined in Section 4. + - The Optional Parameters TLV includes the definition of any of + the Constraint-based TLVs specified in Section 4. - - The Procedures to handle Service Classes are defined in Section - 5. + - The Procedures to handle the Label Request Message are augmented + by the procedures for processing of the CR-TLVs as defined in + Section 4. -3.2 Label Mapping Message + The encoding for the CR-LDP Label Request Message is as follows: + +CR-LDP Specification - 8 - Exp. August 1999 + + 0 1 2 3 + 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + |U| Label Request (0x0401) | Message Length | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | Message ID | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | FEC TLV | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | Return Message ID TLV (mandatory) | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | LSPID TLV (CR-LDP, mandatory) | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | ER-TLV (CR-LDP, optional) | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | Traffic TLV (CR-LDP, optional) | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | Pinning TLV (CR-LDP, optional) | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | Resource Class TLV (CR-LDP, optional) | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | Pre-emption TLV (CR-LDP, optional) | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + +3.3 Label Mapping Message The Label Mapping Message is as defined in 3.5.7 of [LDP] with the following modifications: - Only a single Label-TLV may be included in the Label Mapping Message. -CR-LDP Specification - 5 - Exp. Apr 1999 + - The Label Mapping Message MUST include Label Request Message ID + TLV. - - The FEC-Label Mapping TLV does not include any of the optional - TLVs. + - The Label Mapping Message MUST include LSPID TLV. - The Label Mapping Message Procedures are limited to downstream - on demand ordered control mode of mapping. + on demand ordered control mode. A Mapping message is transmitted by a downstream LSR to an upstream LSR under one of the following conditions: 1. The LSR is the egress end of the CRLSP and an upstream mapping has been requested. 2. The LSR received a mapping from its downstream next hop LSR for an CRLSP for which an upstream request is still pending. -3.3. Notification Message + The encoding for the CR-LDP Label Mapping Message is as follows: - The Notification message is as defined in Section 3.5.1 of [LDP] and +CR-LDP Specification - 9 - Exp. August 1999 + + 0 1 2 3 + 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + |U| Label Mapping (0x0400) | Message Length | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | Message ID | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | FEC TLV | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | Label TLV | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | Label Request Message ID TLV (mandatory) | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | LSPID TLV (CR-LDP, mandatory) | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | Traffic TLV (CR-LDP, optional) | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + +3.4 Notification Message + + The Notification Message is as defined in Section 3.5.1 of [LDP] and the Status TLV encoding is as defined in Section 3.4.7 of [LDP]. Establishment of an Explicitly Routed LSP may fail for a variety of reasons. All such failures are considered advisory conditions and they are signaled by the Notification Message. - Notification messages carry Status TLVs to specify events being - signaled. New status codes are defined in Section 4.8.3 to signal + Notification Messages carry Status TLVs to specify events being + signaled. New status codes are defined in Section 4.11 to signal error notifications associated with the establishment of a CRLSP and the processing of the CR-TLV. -4. Constraint-based Routing TLV + The Notification Message must carry the LSPID TLV of the + corresponding CRLSP. - Label Request Messages defined in [LDP] optionally carry the - Constraint-based Routing TLV (CR-TLV) based on the path vector - defined in [ER] and described in this section of the specification. - The inclusion of the CR TLV in the Label Request Message indicates - the path to be taken in the network even if normal routing indicates - otherwise. +3.5 Release and Withdraw Messages - The format of the CR-TLV is described below. + The Label Release and Label Withdraw Messages are used as specified + in [LDP] to clear CR-LSPs. These message may also carry the LSPID + TLV. -4.1 CR-TLV +4. Protocol Specification - The CR-TLV is an object that specifies the path to be taken by the - LSP being established. In addition, the CR-TLV may also include the - the Service Class (SC) constraints associated with the LSP, a setup - and a holding priority used for path bumping, and an LSP pinning - request flag. Reserved bits in the CR-TLV allow for the - specification of other LSP attributes in the future. If the reserved - bits are exhausted, additional TLVs may be specified to allow for the - indication of other LSP attributes during the CRLSP setup. + The Label Request Messages defined in [LDP] optionally carries one or + more of the optional Constraint-based Routing TLVs (CR-TLVs) defined + in this section. If needed, other constraints can be supported later + through the definition of new TLVs. In this specification, the + following TLVs are defined: -CR-LDP Specification - 6 - Exp. Apr 1999 + - Explicit Route TLV + +CR-LDP Specification - 10 - Exp. August 1999 + + - Explicit Route Hop TLV + - Traffic Parameters TLV + - Preemption TLV + - LSPID TLV + - Route Pinning TLV + - Resource Class TLV + - CRLSP FEC TLV + +4.1 Explicit Route TLV (ER-TLV) + + The ER-TLV is an object that specifies the path to be taken by the + LSP being established. It is composed of one or more Explicit Route + Hop TLVs (ER-Hop TLVs) defined in Section 4.2. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - |U|F| CR-TLV (0x0800) | Length | - +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - | Reserved | Reserved | SC |P| Hp | Sp | + |U|F| ER-TLV (0x0800) | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ER-Hop TLV 1 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ER-Hop TLV 2 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ~ ............ ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ER-Hop TLV n | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ U bit - - Unknown TLV bit. Upon receipt of an unknown TLV, if clear (=0), a - notification must be returned to the message originator and the - entire message must be ignored; if set (=1), the unknown TLV is - silently ignored and the rest of the message is processed as if the - unknown TLV did not exist. + Unknown TLV bit. As defined in [LDP]. F bit - - Forward unknown TLV bit. This bit only applies when the U bit is set - and the LDP message containing the unknown TLV is to be forwarded. - If clear (=0), the unknown TLV is not forwarded with the containing - message; if set (=1), the unknown TLV is forwarded with the - containing message. + Forward unknown TLV bit. As defined in [LDP]. Type + A two byte field carrying the value of the ER-TLV type which + is 0x800. - A two byte field carrying the value of the CR-TLV type which is - 0x800. + Length + Specifies the length of the value field in bytes. + + ER-Hop TLVs + One or more ER-Hop TLVs defined in Section 4.2. + +4.2 Explicit Route Hop TLV (ER-Hop TLV) + + The contents of an ER-TLV are a series of variable length ER-Hop + TLVs. Each ER-Hop TLV has the form: + +CR-LDP Specification - 11 - Exp. August 1999 + + 0 1 2 3 + 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + |U|F| ER-Hop-Type | Length | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + |L| Content // | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + + U bit + Unknown TLV bit. As defined in [LDP]. + + F bit + Forward unknown TLV bit. As defined in [LDP]. + + ER-Hop Type + A fourteen-bit field indicating the type of contents of + the ER-Hop. Currently defined values are: + + Value Type + ----- ------------------------ + 0x801 IPv4 prefix + 0x802 IPv6 prefix + 0x803 Autonomous system number + 0x804 LSPID Length + Specifies the length of the value field in bytes. + L bit + The L bit is an attribute of the ER-Hop. The L bit is set if the + ER-Hop represents a loose hop in the explicit route. If the bit is + not set, the ER-Hop represents a strict hop in the explicit route. + + The L bit in the ER-Hop is a one-bit attribute. If the L bit is + set, then the value of the attribute is "loose." Otherwise, the + value of the attribute is "strict." For brevity, we say that if + the value of the ER-Hop attribute is loose then it is a "loose + ER-Hop." Otherwise, it's a "strict ER-Hop." Further, we say that + the abstract node of a strict or loose ER-Hop is a strict or a + loose node, respectively. Loose and strict nodes are always + interpreted relative to their prior abstract nodes. + + The path between a strict node and its prior node MUST include + only network nodes from the strict node and its prior abstract + node. + + The path between a loose node and its prior node MAY include other + network nodes which are not part of the strict node or its prior + abstract node. + +CR-LDP Specification - 12 - Exp. August 1999 + + Contents + A variable length field containing the node or abstract node that + is the consecutive nodes that make up the explicit routed LSP. + +4.3 Traffic Parameters TLV + + The following sections describe the CRLSP Traffic Parameters. The + required characteristics of a CRLSP are expressed by the Traffic + Parameter values. + + A Traffic Parameters TLV, is used to signal the Traffic Parameter + values. The Traffic Parameters are defined in the subsequent + sections. + + The Traffic Parameters TLV contains a Flags field, a Frequency, a + Weight, and the five Traffic Parameters PDR, PBS, CDR, CBS, EBS. The + Traffic Parameters TLV is shown below: + + 0 1 2 3 + 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + |U|F| Traf. Param. TLV (0x0810)| Length | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | Flags | Frequency | Reserved | Weight | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | Peak Data Rate (PDR) | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | Peak Burst Size (PBS) | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | Committed Data Rate (CDR) | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | Committed Burst Size (CBS) | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | Excess Burst Size (EBS) | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + + U bit + Unknown TLV bit. As defined in [LDP]. + + F bit + Forward unknown TLV bit. As defined in [LDP]. + + Type + A fourteen-bit field carrying the value of the ER-TLV type which + is 0x810. + + Length Specifies the length of the value field in bytes. + Flags + The Flags field is shown below: + +CR-LDP Specification - 13 - Exp. August 1999 + + +--+--+--+--+--+--+--+--+ + | Res |F6|F5|F4|F3|F2|F1| + +--+--+--+--+--+--+--+--+ + + Res - These bits are reserved. + Zero on transmission. + Ignored on receipt. + F1 - Corresponds to the PDR. + F2 - Corresponds to the PBS. + F3 - Corresponds to the CDR. + F4 - Corresponds to the CBS. + F5 - Corresponds to the EBS. + F6 - Corresponds to the Weight. + + Each flag Fi is a Negotiable Flag corresponding to a Traffic + Parameter. The Negotiable Flag value zero denotes NotNegotiable + and value one denotes Negotiable. + + Frequency + The Frequency field is coded as an 8 bit unsigned integer with + the following code points defined: + + 0 - Unspecified + 1 - Frequent + 2 - VeryFrequest + 3-255 - Reserved + Reserved + Zero on transmission. Ignored on receipt. - This field is reserved. It must be set to zero on transmission and - must be ignored on receipt. We expect to use these fields for - carrying information that support other constrain-based routing - information. + Weight + An 8 bit unsigned integer indicating the weight of the CRLSP. + Valid weight values are from 1 to 255. The value 0 means + that weight is not applicable for the CRLSP. -P bit + Traffic Parameters + Each Traffic Parameter is encoded as a 32 bit IEEE single- + precision floating point number. A value of positive infinity is + represented as an IEEE single-precision floating-point number with + an exponent of all ones (255) and a sign and mantissa of all + zeros. The values PDR and CDR are in units of bytes per second. + The values PBS, CBS and EBS are in units of bytes. -CR-LDP Specification - 7 - Exp. Apr 1999 + The value of PDR MUST be greater than or equal to the value of CDR + in a correctly encoded Traffic Parameters TLV. - When set indicates that the loosely routed segments must remain - pinned-down. CRLSP must be rerouted only when adjacency is lost - along the segment. When not set, it indicates that the loose segment - is not pinned down and must be changed to match the underlying hop- - by-hop path. +4.3.1 Semantics -SC +4.3.1.1 Frequency - The SC Field is used to specify the Service Class of the CRLSP. This - field allows for the definition of up to 8 different Service Classes. - Currently, Three Service Classes are defined: Best Effort (0), - Throughput Sensitive (1), and Delay Sensitive (2) Service Classes. - These SCs are further defined in Section 5. +CR-LDP Specification - 14 - Exp. August 1999 -Sp + The Frequency specifies at what granularity the CDR allocated to the + CRLSP is made available. The value VeryFrequently means that the + available rate should average at least the CDR when measured over any + time interval equal to or longer than the shortest packet time at the + CDR. The value Frequently means that the available rate should + average at least the CDR when measured over any time interval equal + to or longer than a small number of shortest packet times at the CDR. + The value Unspecified means that the CDR MAY be provided at any + granularity. - A SetupPriority of value zero (0) is the priority assigned to the - most important path. It is referred to as the highest priority. Four - (4) is the priority for the least important path. The higher the - setup priority, the more paths CR-LDP can bump to set up the path. - The default value is 2. Values 5, 6, and 7 are reserved. +4.3.1.2 Peak Rate -Hp + The Peak Rate defines the maximum rate at which traffic SHOULD be + sent to the CRLSP. The Peak Rate is useful for the purpose of + resource allocation. If resource allocation within the MPLS domain + depends on the Peak Rate value then it should be enforced at the + ingress to the MPLS domain. - A HoldingPriority of value zero (0) is the priority assigned to the - most important path. It is referred to as the highest priority. Four - (4) is the priority for the least important path. The higher the - holding priority, the less likely it is for CR-LDP to reallocate its - bandwidth to a new path. The default value is 2. Values 5, 6, and 7 - are reserved. + The Peak Rate is defined in terms of the two Traffic Parameters PDR + and PBS, see section 4.3.1.5 below. -4.1.1 Setup and holding priorities +4.3.1.3 Committed Rate - CR-LDP signals the resources required by a path on each hop of the - route. If a route with sufficient resources can not be found, - existing paths may be rerouted to reallocate resources to the new - path. This is the process of bumping paths. Setup and holding - priorities are used to rank existing paths (holding priority) and the - new path (setup priority) to determine if the new path can bump an - existing path. + The Committed Rate defines the rate that the MPLS domain commits to + be available to the CRLSP. - The setupPriority of a new CRLSP and the holdingPriority attributes - of the existing CRLSP are used to specify these priorities. The - higher the holding priority, the less likely it is for CR-LDP to - reallocate its bandwidth to a new path. Similarly, the higher the - setup priority, the more paths CR-LDP can bump to set up the path. + The Committed Rate is defined in terms of the two Traffic Parameters + CDR and CBS, see section 4.3.1.6 below. - The setup and holding priority values range from zero (0) to four - (4). The value zero (0) is the priority assigned to the most - important path. It is referred to as the highest priority. Four (4) - is the priority for the least important path. The default values for +4.3.1.4 Excess Burst Size -CR-LDP Specification - 8 - Exp. Apr 1999 + The Excess Burst Size may be used at the edge of an MPLS domain for + the purpose of traffic conditioning. The EBS MAY be used to measure + the extent by which the traffic sent on a CRLSP exceeds the committed + rate. - both setup and holding priority should be 2. By setting the default - value of both setup and holding priorities at the middle of the - range, all connections are initially treated the same. However, when - network operators see a need for the use of path bumping, the values - of setup and holding priorities can be gracefully adjusted up or down - from the middle of the range. + The possible traffic conditioning actions, such as passing, marking + or dropping, are specific to the MPLS domain. - An existing path can be bumped if and only if the setupPriority of - the new path is numerically less than the holdingPriority of the - existing path. + The Excess Burst Size is defined together with the Committed Rate, + see section 4.3.1.6 below. - To illustrate the use of the setup and holding priority, consider a - network which supports two service types (e.g., video and data - services). The video traffic is given a low setup priority because - new video paths can use an alternate public network if the primary - network cannot accommodate the new path. However, the video traffic - is given a high holding priority since it is undesirable for the path - to be rerouted during an active LSP. For data traffic, high setup and - holding priorities are desirable since data paths cannot be - established on an alternate network. +4.3.1.5 Peak Rate Token Bucket - The setup and holding priorities can be different to allow setup at - one priority and holding at an independent priority. This would allow - some calls not to invoke bumping and not to be bumped at the same - time. + The Peak Rate of a CRLSP is specified in terms of a token bucket P + with token rate PDR and maximum token bucket size PBS. - The setupPriority of a CRLSP should not be higher (numerically less) - than its holdingPriority since it might bump an LSP and be bumped by - next "equivalent" request. + The token bucket P is initially (at time 0) full, i.e., the token + count Tp(0) = PBS. Thereafter, the token count Tp, if less than PBS, + is incremented by one PDR times per second. When a packet of size B + bytes arrives at time t, the following happens: - Bumping by default only happens as a last resort when there are no - routes available for a given path. +CR-LDP Specification - 15 - Exp. August 1999 - During the instantiation of a path that must bump other paths, lower - holding priority paths are bumped before higher priority paths. The - decision as to which of the available paths are bumped at each - intermediate node by the new path is arbitrary. + o If Tp(t)-B >= 0, the packet is not in excess of the peak + rate and Tp is decremented by B down to the minimum value + of 0, else -4.2 ER-Hop TLV + o the packet is in excess of the peak rate and Tp is + not decremented. - The contents of a constraint-based route TLV are a series of variable - length ER-Hop TLVs. Each ER-Hop TLV has the form: + Note that according to the above definition, a positive infinite + value of either PDR or PBS implies that arriving packets are never in + excess of the peak rate. - 0 1 - 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 - +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+--------//--------------+ - |L| Type | Length | Contents | - +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+--------//--------------+ + The actual implementation of a LSR doesn't need to be modeled + according to the above formal token bucket specification. -L +4.3.1.6 Committed Data Rate Token Bucket -CR-LDP Specification - 9 - Exp. Apr 1999 + The committed rate of a CRLSP is specified in terms of a token bucket + C with rate CDR. The extent by which the offered rate exceeds the + committed rate MAY be measured in terms of another token bucket E, + which also operates at rate CDR. The maximum size of the token + bucket C is CBS and the maximum size of the token bucket E is EBS. - The L bit is an attribute of the ER-Hop. The L bit is set if the - ER-Hop represents a loose hop in the explicit route. If the bit is - not set, the ER-Hop represents a strict hop in the explicit route. + The token buckets C and E are initially (at time 0) full, i.e., the + token count Tc(0) = CBS and the token count Te(0) = EBS. Thereafter, + the token counts Tc and Te are updated CDR times per second as + follows: -Type + o If Tc is less than CBS, Tc is incremented by one, else - A seven-bit field indicating the type of contents of the ER-Hop. - Currently defined values are: + o if Te is less then EBS, Te is incremented by one, else - Value Type - ----- ------------------------ - 0 Reserved - 1 IPv4 prefix - 2 IPv6 prefix - 32 Autonomous system number + o neither Tc nor Te is incremented. -Length + When a packet of size B bytes arrives at time t, the following + happens: - The Length field contains the total length of the ER-Hop in bytes. It - includes the L bit, Type and Length fields. The length must always be - a multiple of 4, and at least 4. + o If Tc(t)-B >= 0, the packet is not in excess of the Committed + Rate and Tc is decremented + by B down to the minimum value of 0, else -Contents + o if Te(t)-B >= 0, the packet is in excess of the Committed Rate + but is not in excess of the EBS and Te is + decremented by B down to the minimum value of 0, else - A variable length field containing the node or abstract node that is - the consecutive nodes that make up the explicit routed LSP. + o the packet is in excess of both the Committed Rate and the EBS + and neither Tc nor Tc is decremented. -4.3 Applicability + Note that according to the above specification, a CDR value of + positive infinity implies that arriving packets are never in excess + of either the Committed Rate or EBS. A positive infinite value of + either CBS or EBS implies that the respective limit cannot be - The CR-TLV in this version of the specification is intended for - unicast only. CRLSPs for multicast are FFS. +CR-LDP Specification - 16 - Exp. August 1999 -4.4 Semantics of the CR-TLV + exceeded. - Like any other LSP an CRLSP is a path through a network. The - difference is that while other paths are setup solely based on - information in routing tables or from a management system, the - constraint-based route is calculated at one point at the edge of - network based on criteria, including but not limited to routing - information. The intention is that this functionality shall give - desired special characteristics to the LSP in order to better support - the traffic sent over the LSP. The reason for setting up CRLSPs, - might be that one wants to assign certain bandwidth or other Service - Class characteristics to the LSP, or that one wants to make sure that - alternative routes use physically separate paths through the network. + The actual implementation of a LSR doesn't need to be modeled + according to the above formal specification. - A CRLSP is represented in a Label Request Message as a list of nodes - or groups of nodes along the constraint-based route. When the CRLSP - is established, all or a subset of the nodes in a group may be +4.3.1.7 Weight -CR-LDP Specification - 10 - Exp. Apr 1999 + The weight determines the CRLSP's relative share of the possible + excess bandwidth above its committed rate. The definition of + "relative share" is MPLS domain specific. - traversed by the LSP. Certain operations to be performed along the - path can also be encoded in the constraint-based route. +4.3.2 Procedures - The capability to specify, in addition to specified nodes, groups of - nodes, of which a subset will be traversed by the CRLSP, allows the - system a significant amount of local flexibility in fulfilling a - request for a constraint-based route. This allows the generator of - the constraint-based route to have some degree of imperfect - information about the details of the path. +4.3.2.1 Label Request Message - The constraint-based route is encoded as a series of ER-Hops - contained in a constraint-based route TLV. Each ER-Hop may identify - a group of nodes in the constraint-based route. A constraint-based - route is then a path including all of the identified groups of nodes. + If an LSR receives an incorrectly encoded Traffic Parameters TLV in + which the value of PDR is less than the value of CDR then it MUST + send a Notification Message including the Status code Traffic + Parameters Unavailable to the upstream LSR from which it received the + erroneous message. - To simplify the discussion, we call each group of nodes an abstract - node. Thus, we can also say that a constraint-based route is a path - including all of the abstract nodes, with the specified operations - occurring along that path. + If a Traffic Parameter is indicated as Negotiable in the Label + Request Message by the corresponding Negotiable Flag then an LSR MAY + replace the Traffic Parameter value with a smaller value. -4.5 Strict and Loose ER-Hops + If the Weight is indicated as Negotiable in the Label Request Message + by the corresponding Negotiable Flag then an LSR may adjust replace + the Weight value with a lower value (down to 1). - The L bit in the ER-Hop is a one-bit attribute. If the L bit is set, - then the value of the attribute is "loose." Otherwise, the value of - the attribute is "strict." For brevity, we say that if the value of - the ER-Hop attribute is loose then it is a "loose ER-Hop." - Otherwise, it's a "strict ER-Hop." Further, we say that the abstract - node of a strict or loose ER-Hop is a strict or a loose node, - respectively. Loose and strict nodes are always interpreted relative - to their prior abstract nodes. + If, after possible Traffic Parameter negotiation, an LSR can support + the CRLSP Traffic Parameters then the LSR MUST reserve the + corresponding resources for the CRLSP. - The path between a strict node and its prior node MUST include only - network nodes from the strict node and its prior abstract node. + If, after possible Traffic Parameter negotiation, an LSR cannot + support the CRLSP Traffic Parameters then the LSR MUST send a + notification message that contains the Resource Unavailable status + code. - The path between a loose node and its prior node MAY include other - network nodes which are not part of the strict node or its prior - abstract node. +4.3.2.2 Label Mapping Message -4.6 Loops + If an LSR receives an incorrectly encoded Traffic Parameters TLV in + which the value of PDR is less than the value of CDR then it MUST + send a Label Release message containing the Status code Traffic + Parameters Unavailable to the LSR from which it received the + erroneous message. - While the constraint-based route TLV is of finite length, the - existence of loose nodes implies that it is possible to construct - forwarding loops during transients in the underlying routing - protocol. This may be detected by the originator of the constraint- - based route through the use a path vector object as defined in [LDP]. + The egress LSR MUST include the (possibly negotiated) Traffic + Parameters and Weight in the Label Mapping message. -4.7 ER-Hop semantics + The Traffic Parameters and the Weight in a Label Mapping message MUST + be forwarded unchanged. -4.7.1. ER-Hop 1: The IPv4 prefix +CR-LDP Specification - 17 - Exp. August 1999 - The contents of an IPv4 prefix ER-Hop are a 4 byte IPv4 address, 1 + An LSR SHOULD adjust the resources that it reserved for a CRLSP when + it receives a Label Mapping Message if the Traffic Parameters differ + from those in the corresponding Label Request Message. -CR-LDP Specification - 11 - Exp. Apr 1999 +4.3.2.3 Notification Message - byte of prefix length, and 1 byte of padding. The abstract node - represented by this ER-Hop is the set of nodes which have an IP - address which lies within this prefix. Note that a prefix length of - 32 indicates a single IPv4 node. + If an LSR receives a Notification Message for a CRLSP, it SHOULD + release any resources that it possibly had reserved for the CRLSP. - The length of the IPv4 prefix ER-Hop is 8 bytes. The contents of the - 1 byte of padding must be zero on transmission and must not be - checked on receipt. + In addition, on receiving a Notification Message from a Downstream + LSR that is associated with a Label Request from an upstream LSR, the + local LSR MUST propagate the Notification message using the + procedures in [LDP]. + +4.4 Preemption TLV 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - |L| Type | Length | IPv4 Address (4 bytes) | + |U|F| Preemption-TLV (0x0820) | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - | IPv4 Address (Continued) | Prefix |0 0 0 0 0 0 0 0| + | SetPrio | HoldPrio | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + U bit + Unknown TLV bit. As defined in [LDP]. + + F bit + Forward unknown TLV bit. As defined in [LDP]. + Type + A fourteen-bit field carrying the value of the Preemption-TLV + type which is 0x810. - IPv4 Address 0x01 + Length + Specifies the length of the value field in bytes. + + Reserved + Zero on transmission. Ignored on receipt. + + SetPrio + A SetupPriority of value zero (0) is the priority assigned to the + most important path. It is referred to as the highest priority. + Seven (7) is the priority for the least important path. The higher + the setup priority, the more paths CR-LDP can bump to set up the + path. + + HoldPrio + A HoldingPriority of value zero (0) is the priority assigned to + the most important path. It is referred to as the highest + priority. Seven (7) is the priority for the least important path. + +CR-LDP Specification - 18 - Exp. August 1999 + + The higher the holding priority, the less likely it is for CR-LDP + to reallocate its bandwidth to a new path. + +4.5 LSPID TLV + + LSPID is a unique identifier of a CRLSP within an MPLS network. + + The LSPID is composed of the ingress LSR Router ID and a Locally + unique CRLSP ID to that LSR. + + The LSPID is useful in network management, in CR-LSP repair, and in + using an already established CR-LSP as a hop in an ER-TLV. + + 0 1 2 3 + 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + |U|F| LSPID-TLV (0x0821) | Length | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | Reserved | Local CRLSP ID | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | Ingress LSR Router ID | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + + U bit + Unknown TLV bit. As defined in [LDP]. + + F bit + Forward unknown TLV bit. As defined in [LDP]. + + Type + A fourteen-bit field carrying the value of the LSPID-TLV + type which is 0x821. Length + Specifies the length of the value field in bytes. - A one byte field indicating the total length of the TLV in bytes. It - includes the L-bit, the Type, Length, the IP Address, and the Prefix - fields. The length is always 8 bytes. + Reserved + Zero on transmission. Ignored on receipt. -IP Address + Local CRLSP ID + The Local LSP ID is an identifier of the CRLSP locally unique + within the Ingress LSR originating the CRLDP. - A four byte field indicating the IP Address. + Ingress LSR Router ID + A 4 byte field indicating the Ingress LSR ID. -Prefix Length +4.6 Resource Class (Color) TLV - 1-32 + The Resource Class as defined in [TER] is used to specify which links + are acceptable by this CRLSP. This information allows for the -Padding +CR-LDP Specification - 19 - Exp. August 1999 + + networks topology to be pruned. + + 0 1 2 3 + 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + |U|F| ResCls-TLV (0x0822) | Length | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | RsCls | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + + U bit + Unknown TLV bit. As defined in [LDP]. + + F bit + Forward unknown TLV bit. As defined in [LDP]. + + Type + A fourteen-bit field carrying the value of the ResCls-TLV + type which is 0x822. + + Length + Specifies the length of the value field in bytes. + + RsCls + The Resource Class bit mask indicating which of the + 32 "administrative groups" or "colors" of links + the CRLSP can traverse. + +4.7 ER-Hop semantics + +4.7.1. ER-Hop 1: The IPv4 prefix + + The abstract node represented by this ER-Hop is the set of nodes + which have an IP address which lies within this prefix. Note that a + prefix length of 32 indicates a single IPv4 node. + 0 1 2 3 + 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + |U|F| 0x801 | Length | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + |L| Reserved | PreLen | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | IPv4 Address (4 bytes) | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + + U bit + Unknown TLV bit. As defined in [LDP]. + + F bit + Forward unknown TLV bit. As defined in [LDP]. + +CR-LDP Specification - 20 - Exp. August 1999 + + Type + IPv4 Address 0x801 + + Length + Specifies the length of the value field in bytes. + + L Bit + Set to indicate Loose hop. + Cleared to indicate a strict hop. + + Reserved Zero on transmission. Ignored on receipt. -4.7.2. ER-Hop 2: The IPv6 address + PreLen + Prefix Length 1-32 -CR-LDP Specification - 12 - Exp. Apr 1999 + IP Address + A four byte field indicating the IP Address. + +4.7.2. ER-Hop 2: The IPv6 address 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - |L| Type | Length | IPV6 address (16 bytes) | + |U|F| 0x802 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - | IPV6 address (continued) | + |L| Reserved | PreLen | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | IPV6 address | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | IPV6 address (continued) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | IPV6 address (continued) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - | IPV6 address (continued) | Prefix |0 0 0 0 0 0 0 0| + | IPV6 address (continued) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ -Type + U bit + Unknown TLV bit. As defined in [LDP]. - 0x02 IPv6 address + F bit + Forward unknown TLV bit. As defined in [LDP]. + + Type + 0x802 IPv6 address Length + Specifies the length of the value field in bytes. - The Length contains the total length of the ER-Hop TLV in bytes, - including the Type and Length fields. The Length is always 20. + L Bit + Set to indicate Loose hop. -IPv6 address +CR-LDP Specification - 21 - Exp. August 1999 + + Cleared to indicate a strict hop. + + Reserved + Zero on transmission. Ignored on receipt. + + PreLen + Prefix Length 1-128 + IPv6 address A 128-bit unicast host address. -Prefix Length +4.7.3. ER-Hop 32: The autonomous system number - 1-128 + The abstract node represented by this ER-Hop is the set of nodes + belonging to the autonomous system. -Padding + 0 1 2 3 + 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + |U|F| 0x803 | Length | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + |L| Reserved | AS Number | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + + U bit + Unknown TLV bit. As defined in [LDP]. + F bit + Forward unknown TLV bit. As defined in [LDP]. + + Type + AS Number 0x803 + + Length + Specifies the length of the value field in bytes. + + L Bit + Set to indicate Loose hop. + Cleared to indicate a strict hop. + + Reserved Zero on transmission. Ignored on receipt. -4.7.3. ER-Hop 32: The autonomous system number + AS Number + Autonomous System number - The contents of an autonomous system (AS) number ER-Hop are a 2 byte - autonomous system number. The abstract node represented by this ER- - Hop is the set of nodes belonging to the autonomous system. +4.7.4. ER-Hop 4: LSPID - The length of the AS number ER-Hop is 4 bytes. + The LSPID is used to identify the tunnel ingress point as the next + hop in the ER. This ER-Hop allows for stacking new CR-LSPs within an + already established CR-LSP. It also allows for splicing the CR-LSP + +CR-LDP Specification - 22 - Exp. August 1999 + + being established with an existing CR-LSP. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - |L| Type | Length | Autonomous System number | + |U|F| 0x804 | Length | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + |L| Reserved | Local LSPID | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | Ingress LSR Router ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ -Type + U bit + Unknown TLV bit. As defined in [LDP]. -CR-LDP Specification - 13 - Exp. Apr 1999 + F bit + Forward unknown TLV bit. As defined in [LDP]. - AS Number 0x20 + Type + LSPID 0x804 Length + Specifies the length of the value field in bytes. - A one byte field indicating the total length of the TLV in bytes. It - includes the L-bit, the Type, and Length, and the AS number fields. - The length is always 4 bytes. + L Bit + Set to indicate Loose hop. + Cleared to indicate a strict hop. -AS number + Reserved + Zero on transmission. Ignored on receipt. - A two byte field indicating the AS number. + Local LSPID + A 2 byte field indicating the LSPID which is unique + with reference to the its Ingress LSR. -4.8. Processing of the Constraint-Based Route TLV + Ingress LSR Router ID + A 4 byte field indicating the Ingress LSR ID. + +4.8. Processing of the Explicit Route TLV 4.8.1. Selection of the next hop - A Label Request message containing a constraint-based route TLV must + A Label Request Message containing a explicit route TLV must determine the next hop for this path. Selection of this next hop may involve a selection from a set of possible alternatives. The mechanism for making a selection from this set is implementation dependent and is outside of the scope of this specification. Selection of particular paths is also outside of the scope of this specification, but it is assumed that each node will make a best effort attempt to determine a loop-free path. Note that such best + +CR-LDP Specification - 23 - Exp. August 1999 + efforts may be overridden by local policy. To determine the next hop for the path, a node performs the following steps: - 1) The node receiving the Label Request message must first + 1) The node receiving the Label Request Message must first evaluate the first ER-Hop. If the L bit is not set in the first ER-Hop and if the node is not part of the abstract node described by the first ER-Hop, it has received the message in error, and should return a "Bad initial ER-Hop" error. If the L bit is set and the local node is not part of the abstract node described by the first ER-Hop, the node selects a next hop that is along the path to the abstract node described by the first ER-Hop. If there is no first ER-Hop, the message is also in error and the system - should return a "Bad Constraint-Based Routing TLV" error. + should return a "Bad Explicit Routing TLV" error. 2) If there is no second ER-Hop, this indicates the end of the - constraint-based route. The constraint-based route TLV should be - removed from the Label Request message. This node may or may not - be the end of the LSP. Processing continues with section 4.8.2, - where a new constraint-based route TLV may be added to the Label - Request message. + explicit route. The explicit route TLV should be removed from the + Label Request Message. This node may or may not be the end of the + LSP. Processing continues with section 4.8.2, where a new + explicit route TLV may be added to the Label Request Message. 3) If the node is also a part of the abstract node described by the second ER-Hop, then the node deletes the first ER-Hop and continues processing with step 2, above. Note that this makes the second ER-Hop into the first ER-Hop of the next iteration. -CR-LDP Specification - 14 - Exp. Apr 1999 - 4) The node determines if it is topologically adjacent to the abstract node described by the second ER-Hop. If so, the node selects a particular next hop which is a member of the abstract node. The node then deletes the first ER-Hop and continues processing with section 4.8.2. 5) Next, the node selects a next hop within the abstract node of the first ER-Hop that is along the path to the abstract node of the second ER-Hop. If no such path exists then there are two cases: 5a) If the second ER-Hop is a strict ER-Hop, then there is an error and the node should return a "Bad strict node" error. 5b) Otherwise, if the second ER-Hop is a loose ER-Hop, then the node selects any next hop that is along the path to the next - abstract node. If no path exists, then there is an error, and the - node should return a "Bad loose node" error. + abstract node. If no path exists within the MPLS domain, then + there is an error, and the node should return a "Bad loose node" + error. 6) Finally, the node replaces the first ER-Hop with any ER-Hop that denotes an abstract node containing the next hop. This is - necessary so that when the constraint-based route is received by - the next hop, it will be accepted. + necessary so that when the explicit route is received by the next + hop, it will be accepted. + +CR-LDP Specification - 24 - Exp. August 1999 7) Progress the Label Request Message to the next hop. -4.8.2. Adding ER-Hops to the constraint-based route TLV +4.8.2. Adding ER-Hops to the explicit route TLV - After selecting a next hop, the node may alter the constraint-based - route in the following ways. + After selecting a next hop, the node may alter the explicit route in + the following ways. - If, as part of executing the algorithm in section 4.8.1, the - constraint-based route TLV is removed, the node may add a new - constraint-based route TLV. + If, as part of executing the algorithm in section 4.8.1, the explicit + route TLV is removed, the node may add a new explicit route TLV. Otherwise, if the node is a member of the abstract node for the first ER-Hop, then a series of ER-Hops may be inserted before the first ER-Hop or may replace the first ER-Hop. Each ER-Hop in this series must denote an abstract node that is a subset of the current abstract node. Alternately, if the first ER-Hop is a loose ER-Hop, an arbitrary series of ER-Hops may be inserted prior to the first ER-Hop. -4.8.3. Error subcodes - - In the processing described above, certain errors need to be reported - as part of the Notification message. This section defines the status - codes for the errors described above. - -CR-LDP Specification - 15 - Exp. Apr 1999 - - Status Code Type - -------------------------------------- ---------- - Bad Constraint-Based Routing TLV Error 0x04000001 - Bad Strict Node Error 0x04000002 - Bad Loose Node Error 0x04000003 - Bad Initial ER-Hop Error 0x04000004 - Resource Unavailable 0x04000005 - Service Class Unavailable 0x04000006 - Traffic Parameters Unavailable 0x04000007 - -5.0 CRLSP Service Classes and Traffic Parameters - - The following sections describe the CRLSP Service Classes (SCs), and - their associated traffic parameters. - - The CRLSP Service Class is signaled in the SC Field of the CR-TLV - defined in Section 4.1. - - Three Service Classes are currently supported by CR-LDP: - - Service Class Value - -------------------------- ----- - Best Effort (BE) 0x0 - Throughput Sensitive (TS) 0x1 - Delay Sensitive (DS) 0x2 - - These service classes are specified in the following sections. - -5.1 Best Effort (BE) - - The request of the BE SC implies that there are no expected service - guarantees from the network. The service provided by the network is - the familiar best effort service. - - The Peak Date Rate (PDR) is the only traffic parameter that may be - specified with the BE SC. The specification of the PDR allows the - network to perform traffic shaping and policing functions. - -5.2 Throughput Sensitive (TS) - - In the service model for the Throughput Sensitive SC, the network - commits to deliver with high probability user datagrams at a rate of - at least CDR (Committed Data Rate). The user may transmit at a rate - higher than CDR but datagrams in excess of CDR would have a lower - probability of being delivered. If the user sends at a rate of CDR or - lower the network commits to deliver with high probability all the - user datagrams. - - The TS SC has an associated tolerance to the burstiness of arriving - -CR-LDP Specification - 16 - Exp. Apr 1999 - - user datagrams. This tolerance is defined by the traffic parameter - Committed Burst Tolerance (CBT). - - Ideally, a TS CRLSP request carries with it a rich set of three - traffic parameters (PDR, CDR, and CBT) that accurately describe its - traffic characteristics. This allows the network to perform resource - reservation, traffic shaping, and traffic policing. - - However, for the sake of simplicity of the service definition, the - CDR is the only parameter that MUST always be specified for a TS - CRLSP. A peak data rate parameter (PDR) and a CBT are optional - traffic parameters for the TS SC. - - The network should make every effort to preserve ordering of the - delivered datagrams of a TS CRLSP. - - Network traffic that requires a low packet loss ratio at a given CDR - but is not particularly sensitive to delay and jitter (e.g., network - control traffic) is suited to the TS SC. The selection of the TS SC - is used to signal to the various nodes along the path that the - queuing and scheduling mechanisms used to handle the CRLSP should - provide a low packet loss ratio. - -5.3 Delay Sensitive (DS) - - In the service model for the Delay Sensitive SC, the network commits - to deliver with high probability user datagrams at a rate of CDR - (Committed Data Rate) with minimum delay and delay variation. The - user MUST transmit data at a rate of CDR or lower in order to be - eligible for DS service. Datagrams in excess of CDR may be discarded - by the network. If the user sends at a rate of CDR or lower the - network commits to deliver with high probability all user datagrams - with low delay and delay variation. If the user sends at a rate - higher than CDR the network does not provide any guarantees on the - excess traffic. - - The Delay Sensitive SC has an associated tolerance to the burstiness - of arriving user datagrams. This tolerance is defined by the traffic - parameter Committed Burst Tolerance (CBT). - - Ideally, a DS CRLSP request carries with it a rich set of three - traffic parameters (PDR, CDR, and CBT) that accurately describe its - traffic characteristics. This allows the network to perform resource - reservation, traffic shaping and policing. - - However, for the sake of simplicity of the service definition, the - CDR is the only parameter that MUST always be specified for a DS - CRLSP. A peak data rate parameter (PDR) and a CBT are optional - traffic parameters for the DS SC. - - The network should make every effort to preserve ordering of the - -CR-LDP Specification - 17 - Exp. Apr 1999 - - delivered datagrams of a DS CRLSP. - - Network traffic that requires a low delay and delay variation at a - given CDR (e.g., voice traffic) is suited to the DS SC. The selection - of the DS SC is used to signal to the various nodes along the path - that the queuing and scheduling mechanisms used to handle the CRLSP - should provide low delay and delay variation. - -5.4 Traffic Parameters - - The CRLSP traffic parameters are defined in this section. - - The traffic parameters CDR, CBT and PDR are defined in terms of a - TOKEN_BUCKET_TSPEC as specified in [RFC2215]. The following mapping - of parameters in the TOKEN_BUCKET_TSPEC is used: - - Token rate, r = CDR - Bucket depth, b = CBT - Peak traffic rate, p = PDR - Minimum policed unit, m = 1 - Maximum packet size, M = MTU - - The Traffic Parameters TLV is used to signal the traffic - characteristics of the CRLSP. These traffic parameters are used to - perform functions such as resource reservation, Shaping, and - Policing. See [SIN] for more details. The encoding for the Traffic - Parameters TLV is: +4.9 Route Pinning TLV 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - |U|F| Traffic TLV (0x0810) | Length | - +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - | PDR TLV | - +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - | CDR TLV | + |U|F| 0x823 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - | CBT TLV | + |P| Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ -5.4.1 Peak data rate (PDR) TLV + U bit + Unknown TLV bit. As defined in [LDP]. - The value of traffic parameter PDR is given as a positive integer in - bytes per second. Zero is not a valid value of PDR. + F bit + Forward unknown TLV bit. As defined in [LDP]. - The user may specify the value of PDR depending the SC of the CRLSP. - Specifying the PDR allows the network to use traffic management - functions such as shaping. + Type + Pinning-TLV type 0x823 -CR-LDP Specification - 18 - Exp. Apr 1999 + Length + Specifies the length of the value field in bytes. - 0 1 2 3 - 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 - +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - |U|F| PDR TLV (0x0811) | Length | - +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - | PDR in Bytes/sec | - +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + P Bit + The P bit is set to 1 to indicate that route pinning is requested. + The P bit is set to 0 to indicate that route pinning is not + requested -5.4.2. Committed Data Rate (CDR) + Reserved + Zero on transmission. Ignored on receipt. - The value of traffic parameter CDR is given as a positive integer in - bytes per second. Zero is not a valid value of CDR. +4.10 CRLSP FEC Element - The user may provide a requested value of CDR in the CRLSP request - depending on the SC of the CRLSP. +CR-LDP Specification - 25 - Exp. August 1999 - 0 1 2 3 - 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 - +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - |U|F| CDR TLV (0x0812) | Length | - +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - | CDR in Bytes/sec | - +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + A new FEC element is introduced in this specification to support CR- + LSPs. The CRLDP FEC Element is an opaque FEC. -5.4.3. Committed Burst Tolerance (CBT) + FEC Element Type Value + type name - The value of traffic parameter CBT is given in bytes. Zero is not a - valid value of CBT. + CRLSP 0x04 No value; i.e., 0 value octets; + see below. - The requested value of CBT MUST be no smaller than the MTU of the - originating interface. + CRLSP FEC Element + To be used only in Messages of CR-LSPs. - The user may provide a requested value of CBT in the CRLSP request. - If the user chooses not to specify a requested value of CBT and the - network is policing the traffic, then any excess traffic will be - dropped by the network. + The CR-LSP FEC TLV encoding is as follows: 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - |U|F| CBT TLV (0x0813) | Length | + |U|F| FEC(0x0100) | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - | CBT in Bytes | + | CR-LSP (4) | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ -6. Open Issues - - This section captures the issues that need further study. - -CR-LDP Specification - 19 - Exp. Apr 1999 - - 1) Review the FSM described in Appendix B and extend it by the CR-TLV - processing defined in Sections 4.8.1 and 4.8.2. - - 2) Consider if all three traffic parameters have to be signaled at - all times and if the network should supply default values for the - missing parameters. - - 3) Consider the following extensions to the CR-TLV: - - 3.1) Changing the 'P' bit to "next hop flag" and making it a 2-bit - wide field with the following values: - - - 00 "local repair", which means if it belongs to a loosely - routed segment, and the LSR detects a next hop change, the LSR - will try to establish a new LSP from this point on and switch - it over to the new LSP when it is setup. - - - 01 "global repair", which means when the LSR detects a next - hop change, the LSR will tear down the LSP, the ingress LSR - will try to reestablish another LSP through the new path. - - - 10 "pinned", which means that the loosely routed segments - must remain pinned down. + U bit + Unknown TLV bit. As defined in [LDP]. - - 11 Reserved. + F bit + Forward unknown TLV bit. As defined in [LDP]. - 3.2) Adding one more field "LSPID" before ER-Hop TLV. LSPID can - be used to identify a network wide unique CRLSP. + Type + FEC TLV type 0x0100 - - The first 4 bytes carrying the ingress LSR IP address + Length + Specifies the length of the value field in bytes. - - The second 4 bytes carrying the unique ID value assigned by - the ingress LSR. + CR-LSP FEC Element Type + 0x04 - 4) Consider the following extension to the ER-Hop TLV: + Reserved + Zero on transmission. Ignored on receipt. - For Type field, add one more type, LSPID, which means the current - CRLSP will go through another CRLSP which is identified with this - LSPID value: +4.11 Error subcodes - Value Type - ----- ----- - 4 LSPID + In the processing described above, certain errors need to be reported + as part of the Notification Message. This section defines the status + codes for the errors described in this specification. - Extend processing the LSPID ER-Hop as follows: If the type of ER- - Hop is LSPID, and the other end of this CRLSP is not part of the - constraint-based route TLV, add it to the constraint-based TLV - with L bit turned off. +CR-LDP Specification - 26 - Exp. August 1999 - 5) Consider traffic parameter negotiation and the ability to change - the traffic parameters associated with an already established path + Status Code Type + -------------------------------------- ---------- + Bad Explicit Routing TLV Error 0x04000001 + Bad Strict Node Error 0x04000002 + Bad Loose Node Error 0x04000003 + Bad Initial ER-Hop Error 0x04000004 + Resource Unavailable 0x04000005 + Traffic Parameters Unavailable 0x04000006 + Setup abort 0x04000007 -CR-LDP Specification - 20 - Exp. Apr 1999 +5. Security - without tearing the old path down. + Pre-emption has to be controlled by the MPLS domain. -7. Security + Resource reservation requires the LSRs to have an LSP admission + control function. - No security issues are discussed in this version of the draft. + Normal routing can be bypassed by Traffic Engineered LSPs. -8. Acknowledgments +6. Acknowledgments The messages used to signal the CRLSP setup are based on the work done by the [LDP] team. The Explicit Route object and procedures used in this specification are based on [ER]. The authors would also like to acknowledge the careful review and - comments of Osama Aboul-Magd, Ken Hayward, Greg Wright, Geetha Brown, - Brian Williams, Peter Ashwood-smith, Paul Beaubien, Matthew Yuen, - Liam Casey, and Ankur Anand. + comments of Ken Hayward, Greg Wright, Geetha Brown, Brian Williams, + Paul Beaubien, Matthew Yuen, Liam Casey, and Ankur Anand. -9. References +7. References - [FRAME] Callon et al, "Framework for Multiprotocol Label Switching", - work in progress (draft-ietf-mpls-framework-02), November 1997. + [LDP] Andersson et al, "Label Distribution Protocol Specification" + work in progress (draft-ietf-mpls-ldp-03), Feb. 1999. [ARCH] Rosen et al, "Multiprotocol Label Switching Architecture", - work in progress (draft-ietf-mpls-arch-02), July 1998. - - [LDP] Andersson et al, "Label Distribution Protocol Specification" - work in progress (draft-ietf-mpls-ldp-02.txt), November 1998. + work in progress (draft-ietf-mpls-arch-04), Feb. 1999. - [ER] Guerin et al, "Setting up Reservations on Explicit Paths using - RSVP", work in progress (draft-guerin-expl-path-rsvp-01.txt, November + [FRAME] Callon et al, "Framework for Multiprotocol Label Switching", + work in progress (draft-ietf-mpls-framework-02), November 1997. [TER] Awduche et al, "Requirements for Traffic Engineering Over - MPLS", work in progress (draft-awduche-mpls-traffic-eng-00), April - 1998. + MPLS", work in progress (draft-ietf-mpls-traffic-eng-00), + August 1998. + + [ER] Guerin et al, "Setting up Reservations on Explicit Paths + using RSVP", work in progress (draft-guerin-expl-path-rsvp- + 01) + November 1997. + +CR-LDP Specification - 27 - Exp. August 1999 [VPN1] Heinanen et al, "MPLS Mappings of Generic VPN Mechanisms", - work in progress (draft-heinanen-generic-vpn-mpls-00), August 1998. + work in progress (draft-heinanen-generic-vpn-mpls-00), + August 1998. [VPN2] Jamieson et al, "MPLS VPN Architecture" work in progress (draft-jamieson-mpls-vpn-00), August 1998. - [RFC2215] S. Shenker and J. Wroclawski, General Characterization - Parameters for Integrated Service Network Elements, RFC 2215, Sep - 1997. + [VPN3] T. Li, "CPE based VPNs using MPLS", work in progress (draft- + li-mpls-vpn-00.txt), October 1998. - [SIN] B. Jamoussi, N. Feldman, and L. Andersson, "MPLS Ships in the - Night with ATM", (draft-jamoussi-mpls-sin-00.txt), August 1998. + [LDP-STATE] L. Wu, et. al., "LDP State Machine" work in progress + (draft-ietf-mpls-ldp-state-00), Feb 1999. -CR-LDP Specification - 21 - Exp. Apr 1999 +CR-LDP Specification - 28 - Exp. August 1999 -10. Author Information +8. Author Information - Loa Andersson - Director Bay Architecture Lab, EMEA - Kungsgatan 34, PO Box 1788 - 111 97 Stockholm, Sweden - phone: +46 8 441 78 34 - mobile +46 70 522 78 34 - e-mail: loa_andersson@baynetworks.com +Osama S. Aboul-Magd Loa Andersson +Nortel Networks Director Bay Architecture Lab,EMEA +P O Box 3511 Station C Kungsgatan 34, PO Box 1788 +Ottawa, ON K1Y 4H7 111 97 Stockholm, Sweden +Canada phone: +46 8 441 78 34 +phone: +1 613 763-5827 mobile +46 70 522 78 34 +osama@NortelNetworks.com loa_andersson@baynetworks.com - Ross Callon - IronBridge Networks - 55 Hayden Avenue, - Lexington, MA 02173 - Phone: +1-781-402-8017 - Email: rcallon@ironbridgenetworks.com +Peter Ashwood-Smith Ross Callon +Nortel Networks IronBridge Networks +P O Box 3511 Station C 55 Hayden Avenue, +Ottawa, ON K1Y 4H7 Lexington, MA 02173 +Canada Phone: +1-781-402-8017 +phone: +1 613 763-4534 rcallon@ironbridgenetworks.com +petera@NortelNetworks.com - Ram Dantu - Alcatel USA Inc. - IP Competence Center - 1201 E. Campbell Road.,446-315 - Richadson, TX USA., 75081-2206 - Phone: 972 996 2938 +Ram Dantu Paul Doolan +Alcatel USA Inc. Ennovate Networks +IP Competence Center 330 Codman Hill Rd +1201 E. Campbell Road.,446-315 Marlborough MA 01719 +Richadson, TX USA., 75081-2206 Phone: 978-263-2002 +Phone: 972 996 2938 pdoolan@ennovatenetworks.com Fax: 972 996 5902 - Email: ram.dantu@aud.alcatel.com - - Paul Doolan - Ennovate Networks - 330 Codman Hill Rd - Marlborough MA 01719 - Phone: 978-263-2002 - email: pdoolan@ennovatenetworks.com - - Nancy Feldman - IBM Corp. - 17 Skyline Drive - Hawthorne NY 10532 - Phone: 914-784-3254 - email: nkf@us.ibm.com - - Andre Fredette - Nortel Networks - 3 Federal Street - Billerica, MA 01821 - email: fredette@baynetworks.com - - Eric Gray - Lucent Technologies, Inc - 1600 Osgood St. - North Andover, MA 01847 - email: ewgray@lucent.com - -CR-LDP Specification - 22 - Exp. Apr 1999 - - Joel M. Halpern - Newbridge Networks Inc. - 593 Herndon Parkway - Herndon, VA 20170 - email: jhalpern@newbridge.com - phone: 1-703-736-5954 - fax: 1-703-736-5959 - - Juha Heinanen - Telia Finland, Inc. - Myyrmaentie 2 - 01600 VANTAA - Finland - Tel: +358 303 944 808 - Email: jh@telia.fi - - Bilel Jamoussi - Nortel Networks - P O Box 3511 Station C - Ottawa, ON K1Y 4H7 - Canada - phone: +1 613 765-4814 - email: jamoussi@NortelNetworks.com - - Timothy E. Kilty - Northchurch Communications - 5 Corporate Drive, - Andover, MA 018110 - phone: 978 691-4656 - Email: tkilty@northc.com +ram.dantu@aud.alcatel.com - Andrew G. Malis - Ascend Communications, Inc. - 1 Robbins Road - Westford, MA 01886 - phone: 978 952-7414 - fax: 978 392-2074 - Email: malis@ascend.com +Nancy Feldman Andre Fredette +IBM Corp. Nortel Networks +17 Skyline Drive 3 Federal Street +Hawthorne NY 10532 Billerica, MA 01821 +Phone: 914-784-3254 fredette@baynetworks.com +nkf@us.ibm.com - Muckai K Girish - SBC Technology Resources, Inc. - 4698 Willow Road - Pleasanton, CA 94588 - Phone: (925) 598-1263 - Fax: (925) 598-1321 - Email: mgirish@tri.sbc.com +Eric Gray Joel M. Halpern +Lucent Technologies, Inc Newbridge Networks Inc. +1600 Osgood St. 593 Herndon Parkway +North Andover, MA 01847 Herndon, VA 20170 +Phone: 603-659-3386 phone: 1-703-736-5954 +ewgray@lucent.com jhalpern@newbridge.com - Kenneth Sundell - Ericsson - SE-126 25 Stockholm - Sweden +Juha Heinanen Fiffi Hellstrand +Telia Finland, Inc. Ericsson Telecom AB +Myyrmaentie 2 S-126 25 STOCKHOLM +01600 VANTAA Sweden +Finland Tel: +46 8 719 4933 +Tel: +358 41 500 4808 etxfiff@etxb.ericsson.se +jh@telia.fi -CR-LDP Specification - 23 - Exp. Apr 1999 +CR-LDP Specification - 29 - Exp. August 1999 - email: kenneth.sundell@etx.ericsson.se +Bilel Jamoussi Timothy E. Kilty +Nortel Networks Northchurch Communications +P O Box 3511 Station C 5 Corporate Drive, +Ottawa, ON K1Y 4H7 Andover, MA 018110 +Canada phone: 978 691-4656 +phone: +1 613 765-4814 tkilty@northc.com +jamoussi@NortelNetworks.com - Pasi Vaananen - Nokia Telecommunications - 3 Burlington Woods Drive, Suite 250 - Burlington, MA 01803 - Phone: +1-781-238-4981 - Email: pasi.vaananen@ntc.nokia.com +Andrew G. Malis Muckai K Girish +Ascend Communications, Inc. SBC Technology Resources, Inc. +1 Robbins Road 4698 Willow Road +Westford, MA 01886 Pleasanton, CA 94588 +phone: 978 952-7414 Phone: (925) 598-1263 +fax: 978 392-2074 Fax: (925) 598-1321 +malis@ascend.com mgirish@tri.sbc.com - Tom Worster - General DataComm, Inc. - 5 Mount Royal Ave. - Marlboro MA 01752 - Email: tom.worster@gdc.com +Kenneth Sundell Pasi Vaananen +Ericsson Nokia Telecommunications +SE-126 25 Stockholm 3 Burlington Woods Drive, Suite 250 +Sweden Burlington, MA 01803 +kenneth.sundell@etx.ericsson.se Phone: +1-781-238-4981 + pasi.vaananen@ntc.nokia.com - Liwen Wu - Alcatel U.S.A - 44983 Knoll Square - Ashburn, Va. 20147 - USA +Tom Worster Liwen Wu +General DataComm, Inc. Alcatel U.S.A +5 Mount Royal Ave. 44983 Knoll Square +Marlboro MA 01752 Ashburn, Va. 20147 +tom.worster@gdc.com USA Phone: (703) 724-2619 FAX: (703) 724-2005 - Inet: liwen.wu@adn.alcatel.com + liwen.wu@adn.alcatel.com + +CR-LDP Specification - 30 - Exp. August 1999 Appendix A: CRLSP Establishment Examples -A.1 Strict Constraint-Based Route Example +A.1 Strict Explicit Route Example This appendix provides an example for the setup of a strictly routed CRLSP. In this example, each abstract node is represented by a specific node. The sample network used here is a four node network with two edge LSRs and two core LSRs as follows: a b c LSR1------LSR2------LSR3------LSR4 LSR1 generates a Label Request Message as described in Section 3.1 of this draft and sends it to LSR2. This message includes the CR-TLV. - The CR-TLV is composed by a vector of three ER-Hop TLVs . - The ER-Hop TLVs used in this example are of type 0x01 (IPv4 prefix) + The ER-TLV is composed by a vector of three ER-Hop TLVs . + The ER-Hop TLVs used in this example are of type 0x0801 (IPv4 prefix) with a prefix length of 32. Hence, each ER-Hop TLV identifies a specific node as opposed to a group of nodes. - At LSR2, the following processing of the CR-TLV per Section 4.8.1 of + At LSR2, the following processing of the ER-TLV per Section 4.8.1 of this draft takes place: 1) The first hop is part of the abstract node LSR2. Therefore, the first step passes the test. Go to step 2. -CR-LDP Specification - 24 - Exp. Apr 1999 - 2) There is a second ER-Hop, . Go to step 3. 3) LSR2 is not part of the abstract node described by the second ER-Hop . Go to Step 4. 4) LSR2 determines that it is topologically adjacent to the abstract node described by the second ER-Hop . LSR2 selects a next hop (LSR3) which is the abstract node. LSR2 deletes the first - ER-Hop from the CR-TLV which now becomes . Go to + ER-Hop from the ER-TLV which now becomes . Go to Section 4.8.2. At LSR2, the following processing of Section 4.8.2 takes place: Executing algorithm 4.8.1 did not result in the removal of the - CR-TLV. + ER-TLV. Also, LSR2 is not a member of the abstract node described by the first ER-Hop . Finally, the first ER-Hop is a strict hop. Therefore, processing section 4.8.2 does not result in the insertion of new ER-Hops. The selection of the next hop has been + +CR-LDP Specification - 31 - Exp. August 1999 + already done is step 4 of Section 4.8.1 and the processing of the - CR-TLV is completed at LSR2. In this case, the Label Request - Message including the CR-TLV is progressed by LSR2 to LSR3. + ER-TLV is completed at LSR2. In this case, the Label Request + Message including the ER-TLV is progressed by LSR2 to LSR3. - At LSR3, a similar processing to the CR-TLV takes place except that - the incoming CR-TLV = and the outgoing CR-TLV is . + At LSR3, a similar processing to the ER-TLV takes place except that + the incoming ER-TLV = and the outgoing ER-TLV is . At LSR4, the following processing of section 4.8.1 takes place: 1) The first hop is part of the abstract node LSR4. Therefore, the first step passes the test. Go to step 2. 2) There is no second ER-Hop, this indicates the end of the CRLSP. - The CR-TLV is removed from the Label Request Message. Processing + The ER-TLV is removed from the Label Request Message. Processing continues with Section 4.8.2. At LSR4, the following processing of Section 4.8.2 takes place: - Executing algorithm 4.8.1 resulted in the removal of the CR-TLV. - LSR4 does not add a new CR-TLV. + Executing algorithm 4.8.1 resulted in the removal of the ER-TLV. + LSR4 does not add a new ER-TLV. Therefore, processing section 4.8.2 does not result in the insertion of new ER-Hops. This indicates the end of the CRLSP and - the processing of the CR-TLV is completed at LSR4. + the processing of the ER-TLV is completed at LSR4. At LSR4, processing of Section 3.2 is invoked. The first condition is satisfied (LSR4 is the egress end of the CRLSP and upstream mapping has been requested). Therefore, a Label Mapping Message is generated - -CR-LDP Specification - 25 - Exp. Apr 1999 - by LSR4 and sent to LSR3. At LSR3, the processing of Section 3.2 is invoked. The second condition is satisfied (LSR3 received a mapping from its downstream next hop LSR4 for a CRLSP for which an upstream request is still pending). Therefore, a Label Mapping Message is generated by LSR3 and sent to LSR2. At LSR2, a similar processing to LSR 3 takes place and a Label Mapping Message is sent back to LSR1 which completes the end-to-end CRLSP setup. A.2. Node Groups and Specific Nodes Example A request at an ingress LSR to setup a CRLSP might originate from a management system or an application, the details are implementation specific. The ingress LSR uses information provided by the management system or the application and possibly also information from the routing - database to calculated the constraint-based route and to create the - Label Request Message. + database to calculated the explicit route and to create the Label + Request Message. + +CR-LDP Specification - 32 - Exp. August 1999 The Label request message carries together with other necessary - information a CR-TLV defining the constraint-based routed path. In - our example the list of hops in the ER-Hop TLV is supposed to contain - an abstract node representing a group of nodes, an abstract node + information a ER-TLV defining the explicitly routed path. In our + example the list of hops in the ER-Hop TLV is supposed to contain an + abstract node representing a group of nodes, an abstract node representing a specific node, another abstract node representing a group of nodes, and an abstract node representing a specific egress point. In--{Group 1}--{Specific A}--{Group 2}--{Specific Out: B} - The CR-TLV contains four ER-Hop TLVs: + The ER-TLV contains four ER-Hop TLVs: 1. An ER-Hop TLV that specifies a group of LSR valid for the first abstract node representing a group of nodes (Group 1). 2. An ER-Hop TLV that indicates the specific node (Node A). 3. An ER-Hop TLV that specifies a group of LSRs valid for the second abstract node representing a group of nodes (Group 2). 4. An ER-Hop TLV that indicates the specific egress point for the CRLSP (Node B). All the ER-Hop TLVs are strictly routed nodes. The setup procedure for this CRLSP works as follows: -CR-LDP Specification - 26 - Exp. Apr 1999 - - 1. The ingress node sends the Label Request to a node that is a - member the group of nodes indicated in the first ER-Hop TLV, + 1. The ingress node sends the Label Request Message to a node that + is a member the group of nodes indicated in the first ER-Hop TLV, following normal routing for the specific node (A). 2. The node that receives the message identifies itself as part of the group indicated in the first ER-Hop TLV, and that it is not the specific node (A) in the second. Further it realizes that the specific node (A) is not one of its next hops. 3. It keeps the ER-Hop TLVs intact and sends a Label Request Message to a node that is part of the group indicated in the first ER-Hop TLV (Group 1), following normal routing for the specific @@ -1333,258 +1616,166 @@ the group indicated in the first ER-Hop TLV, and that it is not the specific node (A) in the second ER-Hop TLV. Further it realizes that the specific node (A) is one of its next hops. 5. It removes the first ER-Hop TLVs and sends a Label Request Message to the specific node (A). 6. The specific node (A) recognizes itself in the first ER-Hop TLV. Removes the specific ER-Hop TLV. - 7. It sends a Label Request message to a node that is a member of +CR-LDP Specification - 33 - Exp. August 1999 + + 7. It sends a Label Request Message to a node that is a member of the group (Group 2) indicated in the ER-Hop TLV. 8. The node that receives the message identifies itself as part of the group indicated in the first ER-Hop TLV, further it realizes that the specific egress node (B) is one of its next hops. - 9. It sends a Label Request message to the specific egress node + 9. It sends a Label Request Message to the specific egress node (B). 10. The specific egress node (B) recognizes itself as the egress for the CRLSP, it returns a Label Mapping Message, that will traverse the same path as the Label Request Message in the opposite direction. -CR-LDP Specification - 27 - Exp. Apr 1999 - -Appendix B. CR-LDP Finite State Machine - - In this description of the CR-LDP FSM, behavior relating to the - state of LDP messages is assumed to be defined (implicitly or - explicitly) in [LDP]. In particular, LDP is assumed to retain - state information relating a Label Request made of a downstream - neighbor to the Label Request message(s) of upstream neighbors - (downstream-on-demand mode) which the (downstream) Label Request - is meant to satisfy. This will be true of many potential - applications of LDP, of which CR-LDP is an example. Minimally, - this state should include message IDs of Label Requests (both sent - and received) and the LSR(s) from which pending Label Request(s) - were received. - - The FSM describes CR-LDP behavior in the following operations: - - - Start of CRLSP setup (in which a Label Request is sent); - - - Processing the CR-TLV portion of Label Requests; - - - Completion of CRLSP setup (via Label Mapping messages); - - - Notification of originator when: - - - a loop is detected in a loose constraint-based route segment, - - - an ER-Hop is not reachable from a previous ER-Hop, - - - a next ER-Hop is strict and not directly connected to the - current LSR or - - - the current LSR is strict and is not (part of the abstract - node in) the first ER-Hop in the CR-TLV; - - - Withdrawing a CRLSP. - - For the description, the following pictorial representations may be - used as an aid to understanding: - - LSR 1 LSR 2 ... LSR n - - .-----. .-----. .-----. - | ER | | ER | | ER | - `-----' `-----' `-----' - | CR-TLV CR-TLV ^ | CR-TLV CR-TLV ^ - | Next | | Next | - | Hop | | Hop | - V | V | - .-----. Label .-----. Label Label .-----. - | LDP |----------->| LDP |-------> ... ------->| LDP | - `-----' Request `-----' Request Request `-----' - -CR-LDP Specification - 28 - Exp. Apr 1999 - - CRLSP Setup propagation - - LSR 1 LSR 2 ... LSR n - - .-----. .-----. .-----. - | ER | | ER | | ER | - `-----' `-----' `-----' - ^ Status Status | - | Previous | - | Hop | - | V - .-----. Label .-----. Label Label .-----. - | LDP |<-----------| LDP |<------- ... <-------| LDP | - `-----' Mapping `-----' Mapping Mapping `-----' - - CRLSP Status propagation - - .---------------. - | ER | .---------------. - | Link/Call | | LDP | - | Admission | | | - | Control | | Label | - `---------------' | Allocation | - `---------------' - - Related Tasks - -B.1. CR-LDP Primitives - - The following sections describe the logical interactions between - Constrain-based Route and LDP state machines in terms of - primitives that describe the minimal information exchange - required. These assume an asynchronous exchange model involving - locally significant IDs that is used to tie status of a request to - the initial setup and to allow LDP to relate incoming/outgoing - Label Request messages. A synchronous model - possibly based on - multiple threads - is also possible and would eliminate the need - for IDs. - -B.1.1. CR to LDP Primitives - - LDP_SEND_REQ( TLV_List, To_LSR, Identifier ) - - TLV_List - - TLVs to be sent to a neighboring LSR; includes at least an - -CR-LDP Specification - 29 - Exp. Apr 1999 - - CR-TLV and may contain additional TLVs (i.e. QoS TLVs). - - To_LSR - - The neighbor LSR to which a Label Request is to be sent. - - Identifier - - Locally significant unique identifier. May be used to - associate the Label Request to be sent either with a Label - Request that was previously received (e.g. - LSR 2 above) - or a subsequent CRLSP Status (e.g. - LSR 1 above). - - LDP_SEND_RSP( Status, Identifier ) +CR-LDP Specification - 34 - Exp. August 1999 - Status +Appendix B. QoS Service Examples - Status of a specific CRLSP Setup Request. A Status of zero - indicates success; other Status values are given in Error - Subcodes section. This Status is carried in Label Mapping or - Notification messages to the originator of the CRLSP setup. +B.1 Service Examples - Identifier + Construction of an end-to-end service is the result of the rules + enforced at the edge and the treatment that packets receive at the + network nodes. The rules define the traffic conditioning actions that + are implemented at the edge and they include policing with pass, + mark, and drop capabilities. The edge rules are expected to be + defined by the mutual agreements between the service providers and + their customers and they will constitute an essential part of the + SLA. Therefore edge rules are not included in the signaling protocol. - Locally significant unique identifier used to associate the - Label Mapping to be sent with a Label Request received (e.g. - LSR n above). + Packets treatment at a network node is usually referred to as the + local behavior. Local behavior could be specified in many ways. One + example for local behavior specification is the service frequency + introduced in section 4.3.2.1., together with the resource + reservation rules implemented at the nodes. -B.1.2. LDP to CR Primitives + Edge rules and local behaviors can be viewed as the main building + blocks for the end-to-end service construction. The following table + illustrates the applicability of the building block approach for + constructing different services including those defined for ATM. - CR_RECEIVED_REQ( TLV_List, Identifier ) +Service PDR PBS CDR CBS EBS Service Conditioning +Examples Frequency Action +--------------------------------------------------------------------------- - TLV_List +DS S S =PDR =PBS 0 Frequent drop>PDR - TLVs to be processed by the local constraint-based route - function. +TS S S S S 0 Unspecified drop>PDR,PBS + mark>CDR,CBS - Identifier +BE inf inf inf inf 0 Unspecified - - Locally significant unique identifier used to associate the - received request either with a subsequent further request - or a response. For example, the identifier provided here - would be used in a subsequent LDP_SEND_REQ or LDP_SEND_RSP. +FRS S S CIR ~B_C ~B_E Unspecified drop>PDR,PBS + mark>CDR,CBS,EBS - CR_LSP_STATUS( Status, Identifier ) +ATM-CBR PCR CDVT =PCR =CDVT 0 VeryFrequent drop>PCR - Status +ATM-VBR.3(rt) PCR CDVT SCR MBS 0 Frequent drop>PCR + mark>SCR,MBS - Status of a specific CRLSP Setup Request. A Status of zero - indicates success; other Status values are given in section - Error Subcodes. This Status originated at the remote LSR +ATM-VBR.3(nrt) PCR CDVT SCR MBS 0 Unspecified drop>PCR + mark>SCR,MBS -CR-LDP Specification - 30 - Exp. Apr 1999 +ATM-UBR PCR CDVT - - 0 Unspecified drop>PCR - which either completed the CRLSP setup or determined that - CRLSP setup could not be done. +ATM-GFR.1 PCR CDVT MCR MBS 0 Unspecified drop>PCR - Identifier +CR-LDP Specification - 35 - Exp. August 1999 - Locally significant unique identifier used to associate the - received response with the original request. For example, - this identifier would be the same as was used in the initial - LDP_SEND_REQ. +ATM-GFR.2 PCR CDVT MCR MBS 0 Unspecified drop>PCR + mark>MCR,MFS -B.2. CR-LDP States +int-serv-CL p m r b 0 Frequent drop>p + drop>r,b - This document defines 3 states relative to any one specific CRLSP. - They are: +S= User specified - CR_Non_Existant - no state information exists relative to this - CRLSP; + In the above table, the DS refers to a delay sensitive service where + the network commits to deliver with high probability user datagrams + at a rate of PDR with minimum delay and delay requirements. Datagrams + in excess of PDR will be discarded. - CR_In_Progress - LDP_SEND_REQ has been called in result - of external input (e.g. - management); + The TS refers to a generic throughput sensitive service where the + network commit to deliver with high probability user datagrams at a + rate of at least CDR. The user may transmit at a rate higher than CDR + but datagrams in excess of CDR would have a lower probability of + being delivered. - CR_Established - a successful status has been received from - an earlier setup. + The BE is the best effort service and it implies that there are no + expected service guarantees from the network. - These states are defined such that no additional state is required - to support CRLSPs using LDP at intermediate LSRs than is already - required in LDP. +B.2. Establishing CR-LSP Supporting Real-Time Applications -B.3. CR-LDP Events + In this scenario the customer needs to establish an LSP for + supporting real-time applications such voice and video. The Delay- + sensitive (DS) service is requested in this case. - This document defines 4 events impacting any one specific CRLSP. - They are: + The first step is the specification of the traffic parameters in the + signaling message. The two parameters of interest to the DS service + are the PDR and the PBS and their values are specified by the user + based on his requirements. Since all the traffic parameters are + included in the signaling message, appropriate values must be + assigned to all of them. For DS service, the CDR and the CBS values + are set equal to the PDR and the PBS respectively. An indication of + whether the parameter values are subject to negotiation is flagged. - CR_Start - a CRLSP is required based on an external stimulus - (e.g. - management); + The transport characteristics of the DS service requires that + Frequent frequency to be requested to reflect the real-time delay + requirements of the service. - CR_Req_Received - further CRLSP setup processing is required - based on CR_RECEIVED_REQ (i.e. - from an upstream LSR's CRLSP - Label Request); + In addition to the transport characteristics, both the network + provider and the customer need to agree on the actions enforced at + the edge. The specification of those actions is expected to be a part + of the service level agreement (SLA) negotiation and is not included + in the signaling protocol. For DS service, the edge action is to drop + packets that exceed the PDR and the PBS specifications. - CR_Setup_Complete - CRLSP setup has been successfully completed - based on CR_LSP_STATUS (with success status); + The signaling message will be sent in the direction of the ER path + and the LSP is established following the normal LDP procedures. Each - CR_LSP_Failure - Either a CRLSP could not be established as - requested, or a setup CRLSP has dropped; based on CR_LSP_STATUS - (with error status). +CR-LDP Specification - 36 - Exp. August 1999 -B.4. CR-LDP Transitions + LSR applies its admission control rules. If sufficient resources are + not available and the parameter values are subject to negotiation, + then the LSR could negotiate down either the PDR, the PBS, or both. + The new parameters values are echoed back in the Label Mapping + Message. LSRs might need to re-adjust their resource reservations + based on the new traffic parameter values. - State transitions are defined as follows: +B.3. Establishing CR-LSP Supporting Delay Insensitive Applications -CR-LDP Specification - 31 - Exp. Apr 1999 + In this example we assume that a throughput sensitive (TS) service is + requested. For resource allocation the user assigns values for PDR, + PBS, CDR, and CBS. The negotiation flag is set if the traffic + parameters are subject to negotiation. - State Event Action New State - ==================== ================= ====== =============== - CR_Non_Existant CR_Start 1 CR_In_Progress - CR_Non_Existant CR_Req_Rec 2 CR_Non_Existant - CR_In_Progress CR_Setup_Complete CR_Established - CR_In_Progress CR_LSP_Failure 3 CR_Non_Existant - CR_Established CR_LSP_Failure 3 CR_Non_Existant + Since the service is delay insensitive by definition, the Unspecified + frequency is signaled to indicate that the service frequency is not + an issue. - Actions: + Similar to the previous example, the edge actions are not subject for + signaling and are specified in the service level agreement between + the user and the network provider. - 1) Establish CRLSP state, create CR-TLV information, - LDP_SEND_REQ. - 2) Process CR-TLV (as described in "Processing of - the Constraint-Based Route TLV" section) and either - LDP_SEND_REQ or LDP_SEND_RSP. - 3) Remove state information relative to this CRLSP (may notify - management, other external source initially requiring - setup). + For TS service, the edge rules might include marking to indicate high + discard precedence values for all packets that exceed CDR and the + CBS. The edge rules will also include dropping of packets that are do + not conform to either PDR and PBS. - For the purposes of this transition table, illegal transitions - (not included in the table) are ignored. + Each LSR of the LSP is expected to run its admission control rules + and negotiate traffic parameters down if sufficient resources do not + exist. The new parameters values are echoed back in the Label Mapping + Message. LSRs might need to re-adjust their resources based on the + new traffic parameter values.