--- 1/draft-ietf-mpls-lsp-ping-04.txt 2006-02-05 00:41:11.000000000 +0100 +++ 2/draft-ietf-mpls-lsp-ping-05.txt 2006-02-05 00:41:11.000000000 +0100 @@ -1,22 +1,22 @@ Network Working Group K. Kompella (Juniper) Internet Draft P. Pan (Ciena) -draft-ietf-mpls-lsp-ping-04.txt N. Sheth (Juniper) +draft-ietf-mpls-lsp-ping-05.txt N. Sheth (Juniper) Category: Standards Track D. Cooper (Global Crossing) -Expires: April 2003 G. Swallow (Cisco) +Expires: August 2004 G. Swallow (Cisco) S. Wadhwa (Juniper) R. Bonica (WorldCom) - October 2003 + February 2004 Detecting MPLS Data Plane Failures - *** DRAFT *** + Status of this Memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026. 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. @@ -27,52 +27,53 @@ 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 (2003). All Rights Reserved. + Copyright (C) The Internet Society (2004). 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. Changes since last revision (This section to be removed before publication.) - Clarified that an MPLS echo request/reply can be either an IPv4 or an - IPv6 packet. + *** Changed the format of an L2 circuit ID FEC. Added a sender's PE + address field to uniquely identify the VC ID *** - Expanded on Return Codes (section 3.1). + Further clarified that an MPLS echo request/reply can be either an + IPv4 or an IPv6 packet. - Expanded and reformatted the section on Downstream Mapping. + Added format pictures for LDP IPv4/IPv6 prefixes. - Expanded the section on Receiving an MPLS Echo Request + Clarified the section on Receiving an MPLS Echo Request. Issues (This section to be removed before publication.) - Need to fill out Downstream Verification. - Need to address issues with pinging L3VPN FECs. + Need to add new FEC type for "type 129" L2 circuits. + 1. Introduction This document describes a simple and efficient mechanism that can be used to detect data plane failures in MPLS LSPs. There are two parts to this document: information carried in an MPLS "echo request" and "echo reply"; and mechanisms for transporting the echo reply. The first part aims at providing enough information to check correct operation of the data plane, as well as a mechanism to verify the data plane against the control plane, and thereby localize faults. The second part suggests two methods of reliable reply channels for @@ -191,32 +194,34 @@ Value Meaning ----- ------- 1 MPLS Echo Request 2 MPLS Echo Reply The Reply Mode can take one of the following values: Value Meaning ----- ------- 1 Do not reply - 2 Reply via an IPv4 UDP packet - 3 Reply via an IPv4 UDP packet with Router Alert + 2 Reply via an IPv4/IPv6 UDP packet + 3 Reply via an IPv4/IPv6 UDP packet with Router Alert 4 Reply via application level control channel An MPLS echo request with "Do not reply" may be used for one-way connectivity tests; the receiving router may log gaps in the sequence numbers and/or maintain delay/jitter statistics. An MPLS echo - request would normally have "Reply via an IPv4 UDP packet"; if the - normal IPv4 return path is deemed unreliable, one may use "Reply via - an IPv4 UDP packet with Router Alert" (note that this requires that - all intermediate routers understand and know how to forward MPLS echo - replies). + request would normally have "Reply via an IPv4/IPv6 UDP packet"; if + the normal IP return path is deemed unreliable, one may use "Reply + via an IPv4/IPv6 UDP packet with Router Alert" (note that this + requires that all intermediate routers understand and know how to + forward MPLS echo replies). The echo reply uses the same IP version + number as the received echo request, i.e., an IPv4 encapsulated echo + reply is sent in response to an IPv4 encapsulated echo request. Any application which supports an IP control channel between its control entities may set the Reply Mode to 4 to ensure that replies use that same channel. Further definition of this codepoint is application specific and thus beyond the scope of this docuemnt. Return Codes and Subcodes are described in the next section. The Sender's Handle is filled in by the sender, and returned unchanged by the receiver in the echo reply (if any). There are no @@ -342,28 +346,51 @@ Route Distinguisher of RD-foo-Y. 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 with Route Distinguisher of RD-foo-Y. 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.) 3.2.1. 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. + octet of prefix length in bits; the format is given below. The IPv4 + prefix is in network byte order; if the prefix is shorter than 32 + bits, trailing bits SHOULD be set to zero. See [LDP] for an example + of a Mapping for an IPv4 FEC. + + 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 prefix | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | Prefix Length | Must Be Zero | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 3.2.2. 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. See [LDP] for an example of a Mapping for an IPv6 FEC. + one octet of prefix length in bits; the format is given below. The + IPv6 prefix is in network byte order; if the prefix is shorter than + 128 bits, the trailing bits SHOULD be set to zero. See [LDP] for an + example of a Mapping for an IPv6 FEC. + + 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 + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | IPv6 prefix | + | (16 octets) | + | | + | | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | Prefix Length | Must Be Zero | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 3.2.3. 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 | @@ -452,27 +479,30 @@ | Route Distinguisher | | (8 octets) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Sender's CE ID | Receiver's CE ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Encapsulation Type | Must Be Zero | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 3.2.8. L2 Circuit ID - The value field consists of a remote PE address (the address of the - targetted LDP session), a VC ID and an encapsulation type, as - follows: + The value field consists of the sender's PE address (the source + address of the targetted LDP session), the remote PE address (the + destination address of the targetted LDP session), a VC ID and an + encapsulation type, 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | Sender's PE Address | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Remote PE Address | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | VC ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Encapsulation Type | Must Be Zero | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 3.3. Downstream Mapping The Downstream Mapping object is an optional TLV. Only one @@ -810,97 +838,96 @@ 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 that are not marked "Ignore" are 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 zero. In the latter case, the misunderstood TLVs (only) are included in the reply. If the echo request is good, X notes the interface I over which the - echo was received, and the label stack with which it came. If the - MPLS echo request contained a Downstream Verification object (TBD), - then X must format this information as a Downstream Verification - object and include it in its MPLS echo reply message. + echo was received, and the label stack with which it came. X matches up the labels in the received label stack with the FECs contained in the FEC stack. The matching is done beginning at the - bottom of both stacks and working up. For reporting purposes the + bottom of both stacks, and working up. For reporting purposes the bottom of stack is consided to be stack-depth of 1. This is to establish an absolute reference for the case where the stack may have - more labels than are in the FEC stack and the sender of the ping has - not requested that a Downstream Verification TLV be sent. If there - are more FECs than labels, the extra FECs are assumed to correspond - to Implicit Null Labels. + more labels than are in the FEC stack. + + If there are more FECs than labels, the extra FECs are assumed to + correspond to Implicit Null Labels. Thus for the processing below, + there is never the case where there is a FEC with no corresponding + label. Further the label operation associated with an assumed Null + Label is 'pop and continue processing'. Note: in all the error codes listed in this draft a stack-depth of 0 means "no value specified". This allows compatibility with existing implementations which do not use the Return Subcode field. X sets a variable, call it current-stack-depth, to the number of labels in the received label stack. Processing now continues with the following steps: 1. Check if there is a FEC corresponding to the current-stack- depth. If there is, go to step 2. If not, check if the label is valid on interface I. If it is, continue with step 4. Otherwise X MUST send an MPLS echo reply with a Return Code 11, "No label entry at stack-depth" and a Return Subcode set to current-stack- depth. 2. Check the FEC at the current-stack-depth to determine what - protocol was used to advertise it. If X can determine that no - protocol associated with interface I would have advertised a FEC - of that FEC-Type, X MUST send an MPLS echo reply with a Return - Code 12, "Protocol not associated with interface at FEC stack- - depth" and a Return Subcode set to current-stack-depth. + protocol would be used to advertise it. If it can determine that + no protocol associated with interface I, would have advertised a + FEC of that FEC-Type, X MUST send an MPLS echo reply with a + Return Code 12, "Protocol not associated with interface at FEC + stack-depth" and a Return Subcode set to current-stack-depth. 3. Check that the mapping for the FEC at the current-stack-depth is the corresponding label. If no mapping for the FEC exists, X MUST send an MPLS echo reply with a Return Code 4, "Replying router has no mapping for the FEC at stack-depth" and a Return Subcode set to current- stack-depth. If a mapping is found, but the mapping is not the corresponding label, X MUST send an MPLS echo reply with a Return Code 10, "Mapping for this FEC is not the given label at stack-depth" and a Return Subcode set to current-stack-depth. 4. X determines the label operation. If the operation is to pop and continue processing, X checks the current-stack-depth. If it is one, X MUST send an MPLS echo reply with a Return Code 3, "Replying router is an egress for the FEC at stack depth" and a - Return Subcode set to one. Otherwise, X decrements current- - stack-depth and goes back to step 1. + Return Subcode set to one. Otherwise, X decrements current-stack- + depth and goes back to step 1. If the label operation is pop and switch based on the popped label, X then checks if it is valid to forward a labelled packet. - If it is not valid to forward a labelled packet, or the current- - stack-depth is one, X MUST send an MPLS echo reply with a Return - Code 9, "Label switched but no MPLS forwarding at stack-depth" - and a Return Subcode set to current-stack-depth. Otherwise, X - MUST send an MPLS echo reply with a Return Code 8, "Label - switched at stack-depth" and a Return Subcode set to current- - stack-depth. + If it is, X MUST send an MPLS echo reply with a Return Code 8, + "Label switched at stack-depth" and a Return Subcode set to + current-stack-depth. If it is not valid to forward a labelled + packet, X MUST send an MPLS echo reply with a Return Code 9, + "Label switched but no MPLS forwarding at stack-depth" and a + Return Subcode set to current-stack-depth. This return code is + sent even if current-stack-depth is one. If the label operation is swap, X MUST send an MPLS echo reply with a Return Code 8, "Label switched at stack-depth" and a Return Subcode set to current-stack-depth. If the MPLS echo request contains a downstream mapping TLV, and the MPLS echo reply has either a Return Code of 8, or a Return Code of 9 with a Return Subcode of 1 then Downstream mapping TLVs SHOULD be included for each multipath. - 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. + X uses the procedure in the next subsection to send the 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 @@ -1055,22 +1082,23 @@ Private Use, the Length MUST be at least 4, and the first four octets MUST be that vendor's SMI Enterprise Code, in network octet order. The rest of the Value field is private to the vendor. 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 Information sub-field of the Downstream Mapping TLV was - adapted from text suggested by Curtis Villamizar. + The description of the Multipath Information sub-field of the + Downstream Mapping TLV was adapted from text suggested by Curtis + Villamizar. Appendix This appendix specifies non-normative aspects of detecting MPLS data plane liveness. 5.1. CR-LDP FEC This section describes how a CR-LDP FEC can be included in an Echo Request using the following FEC subtype: @@ -1163,21 +1190,21 @@ 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 (2003). All Rights Reserved. + Copyright (C) The Internet Society (2004). 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