--- 1/draft-ietf-mpls-lsp-ping-01.txt 2006-02-05 00:41:08.000000000 +0100 +++ 2/draft-ietf-mpls-lsp-ping-02.txt 2006-02-05 00:41:08.000000000 +0100 @@ -1,19 +1,19 @@ Network Working Group K. Kompella (Juniper) Internet Draft P. Pan (Ciena) -draft-ietf-mpls-lsp-ping-01.txt N. Sheth (Juniper) +draft-ietf-mpls-lsp-ping-02.txt N. Sheth (Juniper) Category: Standards Track D. Cooper (Global Crossing) -Expires: April 2003 G. Swallow (Cisco) +Expires: September 2003 G. Swallow (Cisco) S. Wadhwa (Juniper) R. Bonica (WorldCom) - October 2002 + March 2003 Detecting MPLS Data Plane Liveness *** DRAFT *** Status of this Memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026. @@ -28,21 +28,21 @@ material or to cite them other than as ``work in progress.'' 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. Copyright Notice - Copyright (C) The Internet Society (2002). All Rights Reserved. + Copyright (C) The Internet Society (2003). All Rights Reserved. Abstract This document describes a simple and efficient mechanism that can be used to detect data plane failures in Multi-Protocol Label Switching (MPLS) Label Switched Paths (LSPs). There are two parts to this document: information carried in an MPLS "echo request" and "echo reply" for the purposes of fault detection and isolation; and mechanisms for reliably sending the echo reply. @@ -95,51 +95,66 @@ To avoid potential Denial of Service attacks, it is recommended to regulate the MPLS ping traffic going to the control plane. A rate limiter should be applied to the well-known UDP port defined below. 1.1. Conventions The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119 [KEYWORDS]. -1.2. Changes since last revision +1.2. Structure of this document + + The body of this memo contains four main parts: motivation, MPLS echo + request/reply packet format, MPLS ping operation, and a reliable + return path. It is suggested that first-time readers skip the actual + packet formats and read the Theory of Operation first; the document + is structured the way it is to avoid forward references. + + The last section (reliable return path for RSVP LSPs) may be removed + in a future revision. + +1.3. Changes since last revision (This section to be removed before publication.) - - Packet format changed; Version Number field added - - Reply modes: "don't reply" added - - Reply flags removed - - Return codes extended - - RSVP session formats modified - - VPN IPv4/v6 formats defined - - L2 VPN endpoint and L2 circuits defined - - Downstream mapping format changed - - Pad and Error Code TLVs introduced - - Aspects dealing with CR-LDP moved to non-normative appendix - - IPR notices and Full Copyright Statement (per 2026) added - - other nits to better conform to 2223bis + - Clarified definition of downstream router/interface. + - Added text for multipath (mostly just taken from Curtis) + - Mandated the use of Router Alert for sending echo requests + - If reply mode says IPv4 with router alert, and the reply is + labeled, the top label MUST be the router alert label + - Expanded the Theory of Operation, and added a section on ECMP + - Expanded checks on receipt of echo requests, per email on list + +1.4. Issues remaining + + (This section to be removed before publication.) + + - Monitoring mode + - Finalize ECMP format and semantics + - Keep or remove replies via control plane? + - Normalize error codes 2. Motivation When an LSP fails to deliver user traffic, the failure cannot always be detected by the MPLS control plane. There is a need to provide a tool that would enable users to detect such traffic "black holes" or misrouting within a reasonable period of time; and a mechanism to isolate faults. In this document, we describe a mechanism that accomplishes these - goals. This mechanism is modeled after the ping/traceroute - philosophy: ping (ICMP echo request [ICMP]) is used for connectivity - checks, and traceroute is used for hop-by-hop fault localization as - well as path tracing. This document specifies a "ping mode" and a - "traceroute" mode for testing MPLS LSPs. + goals. This mechanism is modeled after the ping/traceroute paradigm: + ping (ICMP echo request [ICMP]) is used for connectivity checks, and + traceroute is used for hop-by-hop fault localization as well as path + tracing. This document specifies a "ping mode" and a "traceroute" + mode for testing MPLS LSPs. The basic idea is to test that packets that belong to a particular Forwarding Equivalence Class (FEC) actually end their MPLS path on an LSR that is an egress for that FEC. This document proposes that this test be carried out by sending a packet (called an "MPLS echo request") along the same data path as other packets belonging to this FEC. An MPLS echo request also carries information about the FEC whose MPLS path is being verified. This echo request is forwarded just like any other packet belonging to that FEC. In "ping" mode (basic connectivity check), the packet should reach the end of the @@ -189,22 +204,22 @@ . . | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ The Version Number is currently 1. (Note: the Version Number is to be incremented whenever a change is made that affects the ability of an implementation to correctly parse or process an MPLS echo request/reply. These changes include any syntactic or semantic changes made to any of the fixed fields, or to any TLV or sub-TLV assignment or format that is defined at a certain version number. - The Version Number may not need to be changed if a TLV or sub-TLV is - added.) + The Version Number may not need to be changed if an optional TLV or + sub-TLV is added.) The Message Type is one of the following: Value Meaning ----- ------- 1 MPLS Echo Request 2 MPLS Echo Reply The Reply Mode can take one of the following values: @@ -317,31 +332,31 @@ on an egress LSR with loopback address 192.168.1.1 (learned via LDP), X has two choices. X can send an MPLS echo request with a FEC Stack TLV with a single FEC of type VPN IPv4 prefix with a prefix of 10/8 with the Route Distinguisher for VPN foo. Alternatively, X can send a FEC Stack TLV with two FECs, the first of type LDP IPv4 with a prefix of 192.168.1.1/32 and the second of type of IP VPN with a prefix 10/8 in VPN foo. In either case, the MPLS echo request would have a label stack of <1001, 23456>. (Note: in this example, 1001 is the "outer" label and 23456 is the "inner" label.) -3.1.1. IPv4 Prefix +3.1.1. LDP IPv4 Prefix The value consists of four octets of an IPv4 prefix followed by one octet of prefix length in bits. The IPv4 prefix is in network byte order. See [LDP] for an example of a Mapping for an IPv4 FEC. -3.1.2. IPv6 Prefix +3.1.2. LDP IPv6 Prefix The value consists of sixteen octets of an IPv6 prefix followed by one octet of prefix length in bits. The IPv6 prefix is in network - byte order. + byte order. See [LDP] for an example of a Mapping for an IPv6 FEC. 3.1.3. RSVP IPv4 Session The value has the format below. The value fields are taken from [RFC3209, sections 4.6.1.1 and 4.6.2.1]. 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | IPv4 tunnel end point address | @@ -455,64 +470,129 @@ The Downstream Mapping is an optional TLV in an echo request. The Length is 12 + 4*N octets, where N is the number of Downstream Labels. The Value of a Downstream Mapping has the following format: 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Downstream IPv4 Router ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - | MTU | Address Type | Reserved | + | MTU | Address Type | DS Index | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - | Interface Address | + | Downstream Interface Address | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | Hash Key Type | Depth Limit | Multipath Length | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | IP Address or Next Label | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + . . + . (more IP Addresses or Next Labels) . + . . +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Downstream Label | Protocol | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ . . . . . . +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Downstream Label | Protocol | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ The MTU is the largest MPLS frame (including label stack) that fits - on the interface to the Downstream LSR. The Address Type is one of: + on the interface to the Downstream LSR. The Downstream Interface + Address Type is one of: Type # Address Type ------ ------------ 1 IPv4 2 Unnumbered 'Protocol' is taken from the following table: Protocol # Signaling Protocol ---------- ------------------ 0 Unknown 1 Static 2 BGP 3 LDP 4 RSVP-TE 5 Reserved; see Appendix - The notion of "downstream router" should be explained. Consider an - LSR X. If a packet with outermost label L and TTL n>1 arrived at X - on interface I, X must be able to compute which LSRs could receive - the packet with TTL=n+1, and what label they would see. (It is - outside the scope of this document to specify how this computation - may be done.) The set of these LSRs are the downstream routers (and - their corresponding labels) for X with respect to L. + The notion of "downstream router" and "downstream interface" should + be explained. Consider an LSR X. If a packet that was originated + with TTL n>1 arrived with outermost label L at LSR X, X must be able + to compute which LSRs could receive the packet if it was originated + with TTL=n+1, over which interface the request would arrive and what + label stack those LSRs would see. (It is outside the scope of this + document to specify how this computation is done.) The set of these + LSRs/interfaces are the downstream routers/interfaces (and their + corresponding labels) for X with respect to L. Each pair of + downstream router and interface requires a separate Downstream + Mapping to be added to the reply, and is given a unique DS Index. + (Note that there are multiple Downstream Label fields in each TLV as + the incoming label L may be swapped with a label stack.) The case where X is the LSR originating the echo request is a special - case. X needs to figure out what LSRs would receive a labelled - packet with TTL=1 when X tries to send a packet to the FEC Stack that - is being pinged. + case. X needs to figure out what LSRs would receive the MPLS echo + request for a given FEC Stack that X originates with TTL=1. + + The set of downstream routers at X may be alternative paths (see the + discussion below on ECMP) or simultaneous paths (e.g., for MPLS + multicast). In the former case, the Multipath sub-field is used as a + hint to the sender as to how it may influence the choice of these + alternatives. The Multipath Length is the total length of the + Multipath field (i.e., 4 + 4*M, where M is the number of IP + Address/Next Label fields). The Hash Key Type is taken from the + following table: + + Hash Key Type IP Address or Next Label + -------------------- ------------------------ + 0 no multipath (nothing; M = 0) + 1 label M labels + 2 IP address M IP addresses + 3 label range M/2 low/high label pairs + 4 IP address range M/2 low/high address pairs + 5 no more labels (nothing; M = 0) + 6 All IP addresses (nothing; M = 0) + 7 no match (nothing; M = 0) + + The Depth Limit is applicable only to a label stack, and is the + maximum number of labels considered in the hash; this SHOULD be set + to zero if unspecified or unlimited. + + IP Address or Next Label is an IP address from the range 127/8 or an + next label which will exercise this particular path. + + The semantics of the Hash Key Type and IP Address/Next Label are as + follows: + + type 1 - a list of single labels is provided, any one of which + will + cause the hash to match this MP path. + type 2 - a list of single IP addresses is provided, any one of + which will cause the hash to match this MP path. + type 3 - a list of label ranges is provided, any one of which will + cause the hash to match this MP path. + type 4 - a list of IP address ranges is provided, any one of which + will cause the hash to match this MP path. + type 5 - if no more labels are provided on the stack, this MP path + will apply (can only appear once). + type 6 - Any IP addresses matches. Undertlying labels may go + elsewhere, but all IP takes only one MP path (can only + appear once). + type 7 - no matches are possible given the set of "Multipath + Exercise TLV" provided by prior hops. + + If prior hops provide a "Downstream Multipath Mapping TLV" the labels + and IP addresses should be picked from the set provided in prior + "Multipath Exercise TLV" or "Hash Key Type" of 7 used. 3.3. Pad TLV The value part of the Pad TLV contains a variable number (>= 1) of octets. The first octet takes values from the following table; all the other octets (if any) are ignored. The receiver SHOULD verify that the TLV is received in its entirety, but otherwise ignores the contents of this TLV, apart from the first octet. Value Meaning @@ -522,30 +602,87 @@ 3-255 Reserved for future use 3.4. Error Code The Error Code TLV is currently not defined; its purpose is to provide a mechanism for a more elaborate error reporting structure, should the reason arise. 4. Theory of Operation -4.1. Sending an MPLS Echo Request + An MPLS echo request is used to test a particular LSP. The LSP to be + tested is identified by the "FEC Stack"; for example, if the LSP was + set up via LDP, and is to an egress IP address of 10.1.1.1, the FEC + stack contains a single element, namely, an LDP IPv4 prefix sub-TLV + with value 10.1.1.1/32. If the LSP being tested is an RSVP LSP, the + FEC stack consists of a single element that captures the RSVP Session + and Sender Template which uniquely identifies the LSP. + + FEC stacks can be more complex. For example, one may wish to test a + VPN IPv4 prefix of 10.1/8 that is tunneled over an LDP LSP with + egress 10.10.1.1. The FEC stack would then contain two sub-TLVs, the + first being a VPN IPv4 prefix, and the second being an LDP IPv4 + prefix. If the underlying (LDP) tunnel were not known, or was + considered irrelevant, the FEC stack could be a single element with + just the VPN IPv4 sub-TLV. + + When an MPLS echo request is received, the receiver is expected to do + a number of tests that verify that the control plane and data plane + are both healthy (for the FEC stack being pinged), and that the two + planes are in sync. + +4.1. Dealing with Equal-Cost Multi-Path (ECMP) + + LSPs need not be simple point-to-point tunnels. Frequently, a single + LSP may originate at several ingresses, and terminate at several + egresses; this is very common with LDP LSPs. LSPs for a given FEC + may also have multiple "next hops" at transit LSRs. At an ingress, + there may also be several different LSPs to choose from to get to the + desired endpoint. Finally, LSPs may have backup paths, detour paths + and other alternative paths to take should the primary LSP go down. + + To deal with the last two first: it is assumed that the LSR sourcing + MPLS echo requests can force the echo request into any desired LSP, + so choosing among multiple LSPs at the ingress is not an issue. The + problem of probing the various flavors of backup paths that will + typically not be used for forwarding data unless the primary LSP is + down will not be addressed here. + + Since the actual LSP and path that a given packet may take may not be + known a priori, it is useful if MPLS echo requests can exercise all + possible paths. This, while desirable, may not be practical, because + the algorithms that a given LSR uses to distribute packets over + alternative paths may be proprietary. + + To achieve some degree of coverage of alternate paths, there is a + certain lattitude in choosing the destination IP address and source + UDP port for an MPLS echo request. This is clearly not sufficient; + in the case of traceroute, more lattitude is offered by means of the + "Multipath Exercise" sub-TLV of the Downstream Mapping TLV. This is + used as follows. An ingress LSR periodically sends an MPLS + traceroute message to determine whether there are multipaths for a + given LSP. If so, each hop will provide some information how each of + its downstreams can be exercised. The ingress can then send MPLS + echo requests that exercise these paths. If several transit LSRs + have ECMP, the ingress may attempt to compose these to exercise all + possible paths. However, full coverage may not be possible. + +4.2. Sending an MPLS Echo Request An MPLS echo request is a (possibly) labelled UDP packet. The IP header is set as follows: the source IP address is a routable address of the sender; the destination IP address is a (randomly chosen) address from 127/8; the IP TTL is set to 1. The source UDP port is chosen by the sender; the destination UDP port is set to 3503 - (assigned by IANA for MPLS echo requests). If the echo request is - labelled, the MPLS TTL on all the labels except the outermost should - be set to 1. + (assigned by IANA for MPLS echo requests). The Router Alert option + is set in the IP header. If the echo request is labelled, the MPLS + TTL on all the labels except the outermost should be set to 1. In "ping" mode (end-to-end connectivity check), the TTL in the outermost label is set to 255. In "traceroute" mode (fault isolation mode), the TTL is set successively to 1, 2, .... The sender chooses a Sender's Handle, and a Sequence Number. When sending subsequent MPLS echo requests, the sender SHOULD increment the sequence number by 1. However, a sender MAY choose to send a group of echo requests with the same sequence number to improve the chance of arrival of at least one packet with that sequence number. @@ -556,95 +693,101 @@ An MPLS echo request MUST have a FEC Stack TLV. Also, the Reply Mode must be set to the desired reply mode; the Return Code and Subcode are set to zero. In the "traceroute" mode, the echo request SHOULD contain one or more Downstream Mapping TLVs. For TTL=1, all the downstream routers (and corresponding labels) for the sender with respect to the FEC Stack being pinged SHOULD be sent in the echo request. For n>1, the Downstream Mapping TLVs from the echo reply for TTL=(n-1) are copied - to the echo request with TTL=n. + to the echo request with TTL=n; the sender MAY choose to reduce the + size of a "Downstream Multipath Mapping TLV" when copying into the + next echo request as long as the Hash Key Type matching the label or + IP address used to exercise the current MP is still present. -4.2. Receiving an MPLS Echo Request +4.3. Receiving an MPLS Echo Request - An LSR L that receives an MPLS echo request first parses the packet + An LSR X that receives an MPLS echo request first parses the packet to ensure that it is a well-formed packet, and that the TLVs are - understood. If not, L SHOULD send an MPLS echo reply with the - Return Code set to "Malformed echo request received" or "TLV not - understood" (as appropriate), and the Subcode set to the appropriate - value. + understood. If not, X SHOULD send an MPLS echo reply with the Return + Code set to "Malformed echo request received" or "TLV not understood" + (as appropriate), and the Subcode set to the appropriate value. - If the echo request is good, L then checks whether it is a valid - transit or egress LSR for the FEC in the echo request. If not, L MAY - log this fact. + If the echo request is good, X then checks whether it is a valid + transit or egress LSR for the FEC in the echo request. If not, X MAY + log this fact. If it is, X notes that interface I over which the + echo was received, and the label L with which it came. X checks + whether it actually advertised L over interface I for the FEC in the + echo request. - If the echo request contains a Downstream Mapping TLV, L MUST further + If the echo request contains a Downstream Mapping TLV, X MUST further check whether its Router ID matches one of the Downstream IPv4 Router IDs; and if so, whether the given Downstream Label is in fact the - label that L sent as its mapping for the FEC. For an RSVP FEC, the - downstream label is the label that L sent in its Resv message. The - result of the checks in the previous and this paragraph are captured - in the Return Code/Subcode. + label that X sent as its mapping for the FEC over the downstream + interface. The result of the checks in the previous and this + paragraph are captured in the Return Code/Subcode. - If the echo request has a Reply Mode that wants a reply, L uses the + If the echo request has a Reply Mode that wants a reply, X uses the procedure in the next subsection to send the echo reply. -4.3. Sending an MPLS Echo Reply +4.4. Sending an MPLS Echo Reply An MPLS echo reply is a UDP packet. It MUST ONLY be sent in response to an MPLS echo request. The source IP address is a routable address of the replier; the source port is the well-known UDP port for MPLS ping. The destination IP address and UDP port are copied from the source IP address and UDP port of the echo request. The IP TTL is set to 255. If the Reply Mode in the echo request is "Reply via an IPv4 UDP packet with Router Alert", then the IP header MUST contain - the Router Alert IP option. + the Router Alert IP option. If the reply is sent over an LSP, the + topmost label MUST in this case be the Router Alert label (1) (see + [LABEL-STACK]). The format of the echo reply is the same as the echo request. The Sender's Handle, the Sequence Number and TimeStamp Sent are copied from the echo request; the TimeStamp Received is set to the time-of- day that the echo request is received (note that this information is most useful if the time-of-day clocks on the requestor and the replier are synchronized). The FEC Stack TLV from the echo request MAY be copied to the reply. The replier MUST fill in the Return Code and Subcode, as determined in the previous subsection. If the echo request contains a Pad TLV, the replier MUST interpret the first octet for instructions regarding how to reply. If the echo request contains a Downstream Mapping TLV, the replier SHOULD compute its downstream routers and corresponding labels for the incoming label, and add Downstream Mapping TLVs for each one to the echo reply it sends back. -4.4. Receiving an MPLS Echo Reply +4.5. Receiving an MPLS Echo Reply An LSR X should only receive an MPLS Echo Reply in response to an MPLS Echo Request that it sent. Thus, on receipt of an MPLS Echo Reply, X should parse the packet to assure that it is well-formed, then attempt to match up the Echo Reply with an Echo Request that it had previously sent, using the destination UDP port and the Sender's Handle. If no match is found, then X jettisons the Echo Reply; otherwise, it checks the Sequence Number to see if it matches. Gaps in the Sequence Number MAY be logged and SHOULD be counted. Once an Echo Reply is received for a given Sequence Number (for a given UDP port and Handle), the Sequence Number for subsequent Echo Requests for that UDP port and Handle SHOULD be incremented. If the Echo Reply contains Downstream Mappings, and X wishes to traceroute further, it SHOULD copy the Downstream Mappings into its next Echo Request (with TTL incremented by one). -4.5. Non-compliant Routers +4.6. Non-compliant Routers If the egress for the FEC Stack being pinged does not support MPLS ping, then no reply will be sent, resulting in possible "false negatives". If in "traceroute" mode, a transit LSR does not support MPLS ping, then no reply will be forthcoming from that LSR for some TTL, say n. The LSR originating the echo request SHOULD try sending the echo request with TTL=n+1, n+2, ..., n+k in the hope that some transit LSR further downstream may support MPLS echo requests and reply. In such a case, the echo request for TTL>n MUST NOT have Downstream Mapping TLVs, until a reply is received with a Downstream @@ -720,21 +863,21 @@ If X does not receive an Resv message from the egress LSR that contains an LSP_ECHO object within some period of time, it declares the LSP as "down". At this point, the ingress LSR may apply the necessary procedures to fix the LSP. These may include generating a message to network management, tearing-down and re-building the LSP, and/or rerouting user traffic to a backup LSP. To test an LSP that carries non-IP traffic, before injecting ICMP and MPLS ping messages into the LSP, the IPv4 Explicit NULL label should be prepended to such messages. The ingress and egress LSR's must - follow the procedures defined in [LABEL-STACKING]. + follow the procedures defined in [LABEL-STACK]. 5.4. Procedures at the egress LSR When the egress LSR receives an MPLS ping message, it follows the procedures given above. If the Reply Mode is set to "Reply via the control plane", the LSR can, based on the RSVP SESSION and SENDER_TEMPLATE objects carried in the MPLS ping message, find the corresponding LSP in its RSVP-TE database. The LSR then checks to see if the Resv message for this LSP contains an LSP_ECHO object with the same source UDP port value. If not, the LSR adds or updates the @@ -750,21 +893,21 @@ Note that an intermediate LSR using RSVP refresh reduction [RSVP- REFRESH], the new or changed LSP_ECHO object will cause the LSR to classify the RSVP message as a trigger message. 6. Normative References [KEYWORDS] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. - [LABEL-STACKING] Rosen, E., et al, "MPLS Label Stack Encoding", RFC + [LABEL-STACK] Rosen, E., et al, "MPLS Label Stack Encoding", RFC 3032, January 2001. [RSVP] Braden, R. (Editor), et al, "Resource ReSerVation protocol (RSVP) -- Version 1 Functional Specification," RFC 2205, September 1997. [RSVP-REFRESH] Berger, L., et al, "RSVP Refresh Overhead Reduction Extensions", RFC 2961, April 2001. [RSVP-TE] Awduche, D., et al, "RSVP-TE: Extensions to RSVP for LSP @@ -804,20 +947,23 @@ 9. IANA Considerations (To be filled in a later revision) 10. Acknowledgments This document is the outcome of many discussions among many people, that include Manoj Leelanivas, Paul Traina, Yakov Rekhter, Der-Hwa Gan, Brook Bailey, Eric Rosen and Ina Minei. + The Multipath Exercise sub-field of the Downstream Mapping TLV was + adapted from text suggested by Curtis Villamizar. + 11. Appendix This appendix specifies non-normative aspects of detecting MPLS data plane liveness. 11.1. CR-LDP FEC This section describes how a CR-LDP FEC can be included in an Echo Request using the following FEC subtype: @@ -909,21 +1055,21 @@ be obtained from the IETF Secretariat. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights which may cover technology that may be required to practice this standard. Please address the information to the IETF Executive Director. Full Copyright Statement - Copyright (C) The Internet Society (2002). All Rights Reserved. + Copyright (C) The Internet Society (2003). All Rights Reserved. This document and translations of it may be copied and furnished to others, and derivative works that comment on or otherwise explain it or assist in its implmentation may be prepared, copied, published and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this paragraph are included on all such copies and derivative works. However, this document itself may not be modified in any way, such as by removing the copyright notice or references to the Internet Society or other Internet organizations, except as needed for the purpose of