--- 1/draft-smack-mpls-rfc4379bis-08.txt 2015-12-18 10:17:10.853676135 -0800 +++ 2/draft-smack-mpls-rfc4379bis-09.txt 2015-12-18 10:17:10.977679144 -0800 @@ -1,24 +1,24 @@ Network Working Group K. Kompella -Internet-Draft Juniper Networks, Inc. +Internet-Draft Juniper Networks Obsoletes: 4379, 6829 (if approved) C. Pignataro Intended status: Standards Track N. Kumar -Expires: May 22, 2016 Cisco +Expires: June 20, 2016 Cisco S. Aldrin Google M. Chen Huawei - November 19, 2015 + December 18, 2015 Detecting Multi-Protocol Label Switched (MPLS) Data Plane Failures - draft-smack-mpls-rfc4379bis-08 + draft-smack-mpls-rfc4379bis-09 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. @@ -32,21 +32,21 @@ Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. 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." - This Internet-Draft will expire on May 22, 2016. + This Internet-Draft will expire on June 20, 2016. Copyright Notice Copyright (c) 2015 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents @@ -71,55 +71,59 @@ 3.1. Return Codes . . . . . . . . . . . . . . . . . . . . . . 13 3.2. Target FEC Stack . . . . . . . . . . . . . . . . . . . . 13 3.2.1. LDP IPv4 Prefix . . . . . . . . . . . . . . . . . . . 15 3.2.2. LDP IPv6 Prefix . . . . . . . . . . . . . . . . . . . 15 3.2.3. RSVP IPv4 LSP . . . . . . . . . . . . . . . . . . . . 15 3.2.4. RSVP IPv6 LSP . . . . . . . . . . . . . . . . . . . . 16 3.2.5. VPN IPv4 Prefix . . . . . . . . . . . . . . . . . . . 16 3.2.6. VPN IPv6 Prefix . . . . . . . . . . . . . . . . . . . 17 3.2.7. L2 VPN Endpoint . . . . . . . . . . . . . . . . . . . 18 3.2.8. FEC 128 Pseudowire - IPv4 (Deprecated) . . . . . . . 18 - 3.2.9. FEC 128 Pseudowire - IPv4 (Current) . . . . . . . . . 19 - 3.2.10. FEC 129 Pseudowire - IPv4 . . . . . . . . . . . . . . 20 - 3.2.11. BGP Labeled IPv4 Prefix . . . . . . . . . . . . . . . 21 - 3.2.12. BGP Labeled IPv6 Prefix . . . . . . . . . . . . . . . 21 - 3.2.13. Generic IPv4 Prefix . . . . . . . . . . . . . . . . . 22 - 3.2.14. Generic IPv6 Prefix . . . . . . . . . . . . . . . . . 22 - 3.2.15. Nil FEC . . . . . . . . . . . . . . . . . . . . . . . 23 - 3.2.16. FEC 128 Pseudowire - IPv6 . . . . . . . . . . . . . . 23 - 3.2.17. FEC 129 Pseudowire - IPv6 . . . . . . . . . . . . . . 24 - 3.3. Downstream Mapping . . . . . . . . . . . . . . . . . . . 25 - 3.3.1. Multipath Information Encoding . . . . . . . . . . . 28 - 3.3.2. Downstream Router and Interface . . . . . . . . . . . 30 - 3.4. Pad TLV . . . . . . . . . . . . . . . . . . . . . . . . . 31 - 3.5. Vendor Enterprise Number . . . . . . . . . . . . . . . . 31 - 3.6. Interface and Label Stack . . . . . . . . . . . . . . . . 32 - 3.7. Errored TLVs . . . . . . . . . . . . . . . . . . . . . . 33 - 3.8. Reply TOS Byte TLV . . . . . . . . . . . . . . . . . . . 33 - 4. Theory of Operation . . . . . . . . . . . . . . . . . . . . . 34 - 4.1. Dealing with Equal-Cost Multi-Path (ECMP) . . . . . . . . 34 - 4.2. Testing LSPs That Are Used to Carry MPLS Payloads . . . . 35 - 4.3. Sending an MPLS Echo Request . . . . . . . . . . . . . . 35 - 4.4. Receiving an MPLS Echo Request . . . . . . . . . . . . . 36 - 4.4.1. FEC Validation . . . . . . . . . . . . . . . . . . . 42 - 4.5. Sending an MPLS Echo Reply . . . . . . . . . . . . . . . 43 - 4.6. Receiving an MPLS Echo Reply . . . . . . . . . . . . . . 44 - 4.7. Issue with VPN IPv4 and IPv6 Prefixes . . . . . . . . . . 44 - 4.8. Non-compliant Routers . . . . . . . . . . . . . . . . . . 45 - 5. Security Considerations . . . . . . . . . . . . . . . . . . . 45 - 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 46 - 6.1. Message Types, Reply Modes, Return Codes . . . . . . . . 47 - 6.2. TLVs . . . . . . . . . . . . . . . . . . . . . . . . . . 47 - 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 48 - 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 49 - 8.1. Normative References . . . . . . . . . . . . . . . . . . 49 - 8.2. Informative References . . . . . . . . . . . . . . . . . 50 + 3.2.9. FEC 128 Pseudowire - IPv4 (Current) . . . . . . . . . 18 + 3.2.10. FEC 129 Pseudowire - IPv4 . . . . . . . . . . . . . . 19 + 3.2.11. BGP Labeled IPv4 Prefix . . . . . . . . . . . . . . . 20 + 3.2.12. BGP Labeled IPv6 Prefix . . . . . . . . . . . . . . . 20 + 3.2.13. Generic IPv4 Prefix . . . . . . . . . . . . . . . . . 21 + 3.2.14. Generic IPv6 Prefix . . . . . . . . . . . . . . . . . 21 + 3.2.15. Nil FEC . . . . . . . . . . . . . . . . . . . . . . . 22 + 3.2.16. FEC 128 Pseudowire - IPv6 . . . . . . . . . . . . . . 22 + 3.2.17. FEC 129 Pseudowire - IPv6 . . . . . . . . . . . . . . 23 + 3.3. Downstream Mapping (Deprecated) . . . . . . . . . . . . . 24 + 3.4. Downstream Detailed Mapping . . . . . . . . . . . . . . . 24 + 3.4.1. Multipath Information Encoding . . . . . . . . . . . 24 + 3.4.2. Downstream Router and Interface . . . . . . . . . . . 26 + 3.5. Pad TLV . . . . . . . . . . . . . . . . . . . . . . . . . 27 + 3.6. Vendor Enterprise Number . . . . . . . . . . . . . . . . 27 + 3.7. Interface and Label Stack . . . . . . . . . . . . . . . . 27 + 3.8. Errored TLVs . . . . . . . . . . . . . . . . . . . . . . 29 + 3.9. Reply TOS Byte TLV . . . . . . . . . . . . . . . . . . . 29 + 4. Theory of Operation . . . . . . . . . . . . . . . . . . . . . 29 + 4.1. Dealing with Equal-Cost Multi-Path (ECMP) . . . . . . . . 30 + 4.2. Testing LSPs That Are Used to Carry MPLS Payloads . . . . 31 + 4.3. Sending an MPLS Echo Request . . . . . . . . . . . . . . 31 + 4.4. Receiving an MPLS Echo Request . . . . . . . . . . . . . 32 + 4.4.1. FEC Validation . . . . . . . . . . . . . . . . . . . 38 + 4.5. Sending an MPLS Echo Reply . . . . . . . . . . . . . . . 39 + 4.6. Receiving an MPLS Echo Reply . . . . . . . . . . . . . . 40 + 4.7. Issue with VPN IPv4 and IPv6 Prefixes . . . . . . . . . . 40 + 4.8. Non-compliant Routers . . . . . . . . . . . . . . . . . . 41 + 5. Security Considerations . . . . . . . . . . . . . . . . . . . 41 + 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 42 + 6.1. Message Types, Reply Modes, Return Codes . . . . . . . . 43 + 6.2. TLVs . . . . . . . . . . . . . . . . . . . . . . . . . . 43 + 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 44 + 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 45 + 8.1. Normative References . . . . . . . . . . . . . . . . . . 45 + 8.2. Informative References . . . . . . . . . . . . . . . . . 46 + Appendix A. Deprecated TLVs . . . . . . . . . . . . . . . . . . 47 + A.1. FEC 128 Pseudowire . . . . . . . . . . . . . . . . . . . 47 + A.2. Downstream Mapping(DSMAP) . . . . . . . . . . . . . . . . 48 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 51 1. Introduction This document describes a simple and efficient mechanism that can be used to detect data plane failures in MPLS Label Switched Paths (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 @@ -469,22 +473,22 @@ . . | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Types are defined below; Length is the length of the Value field in octets. The Value field depends on the Type; it is zero padded to align to a 4-octet boundary. TLVs may be nested within other TLVs, in which case the nested TLVs are called sub-TLVs. Sub-TLVs have independent types and MUST also be 4-octet aligned. - Two examples follow. The Label Distribution Protocol (LDP) IPv4 FEC - sub-TLV has the following format: + Two examples of how TLV and sub-TLV length are computed, and of how + sub-TLVs are padded to be 4-octet aligned 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type = 1 (LDP IPv4 FEC) | Length = 5 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | IPv4 prefix | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Prefix Length | Must Be Zero | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ @@ -610,36 +614,36 @@ An MPLS echo request MUST have a Target FEC Stack that describes the FEC Stack being tested. For example, if an LSR X has an LDP mapping [RFC5036] for 192.168.1.1 (say, label 1001), then to verify that label 1001 does indeed reach an egress LSR that announced this prefix via LDP, X can send an MPLS echo request with an FEC Stack TLV with one FEC in it, namely, of type LDP IPv4 prefix, with prefix 192.168.1.1/32, and send the echo request with a label of 1001. Say LSR X wanted to verify that a label stack of <1001, 23456> is the - right label stack to use to reach a VPN IPv4 prefix [see section - 3.2.5] of 10/8 in VPN foo. Say further that LSR Y with loopback - address 192.168.1.1 announced prefix 10/8 with Route Distinguisher - RD-foo-Y (which may in general be different from the Route - Distinguisher that LSR X uses in its own advertisements for VPN foo), - label 23456 and BGP next hop 192.168.1.1 [RFC4271]. Finally, suppose - that LSR X receives a label binding of 1001 for 192.168.1.1 via LDP. - X has two choices in sending an MPLS echo request: X can send an MPLS - echo request with an FEC Stack TLV with a single FEC of type VPN IPv4 - prefix with a prefix of 10/8 and a Route Distinguisher of RD-foo-Y. - Alternatively, X can send an 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.) + right label stack to use to reach a VPN IPv4 prefix [see + Section 3.2.5] of 10/8 in VPN foo. Say further that LSR Y with + loopback address 192.168.1.1 announced prefix 10/8 with Route + Distinguisher RD-foo-Y (which may in general be different from the + Route Distinguisher that LSR X uses in its own advertisements for VPN + foo), label 23456 and BGP next hop 192.168.1.1 [RFC4271]. Finally, + suppose that LSR X receives a label binding of 1001 for 192.168.1.1 + via LDP. X has two choices in sending an MPLS echo request: X can + send an MPLS echo request with an FEC Stack TLV with a single FEC of + type VPN IPv4 prefix with a prefix of 10/8 and a Route Distinguisher + of RD-foo-Y. Alternatively, X can send an 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 IPv4 Prefix FEC is defined in [RFC5036]. When an LDP IPv4 prefix is encoded in a label stack, the following format is used. The value consists of 4 octets of an IPv4 prefix followed by 1 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 [RFC5036] for an example of a Mapping for an IPv4 FEC. @@ -770,21 +774,21 @@ | IPv6 prefix | | | | | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Prefix Length | Must Be Zero | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ The Route Distinguisher is identical to the VPN IPv4 Prefix RD, except that it functions here to allow the creation of distinct - routes to IPv6 prefixes. See section 3.2.5. When matching this + routes to IPv6 prefixes. See Section 3.2.5. When matching this field to local FEC information, it is treated as an opaque value. 3.2.7. L2 VPN Endpoint VPLS stands for Virtual Private LAN Service. The terms VPLS BGP NLRI and VE ID (VPLS Edge Identifier) are defined in [RFC4761]. This document uses the simpler term L2 VPN endpoint when referring to a VPLS BGP NLRI. The Route Distinguisher is an 8-octet identifier used to distinguish information about various L2 VPNs advertised by a node. The VE ID is a 2-octet identifier used to identify a @@ -806,49 +810,21 @@ | Route Distinguisher | | (8 octets) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Sender's VE ID | Receiver's VE ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Encapsulation Type | Must Be Zero | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 3.2.8. FEC 128 Pseudowire - IPv4 (Deprecated) - FEC 128 (0x80) is defined in [RFC4447], as are the terms PW ID - (Pseudowire ID) and PW Type (Pseudowire Type). A PW ID is a non-zero - 32-bit connection ID. The PW Type is a 15-bit number indicating the - encapsulation type. It is carried right justified in the field below - termed encapsulation type with the high-order bit set to zero. Both - of these fields are treated in this protocol as opaque values. - - When an FEC 128 is encoded in a label stack, the following format is - used. The value field consists of the remote PE IPv4 address (the - destination address of the targeted LDP session), the PW ID, and the - 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 - +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - | Remote PE IPv4 Address | - +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - | PW ID | - +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - | PW Type | Must Be Zero | - +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - - This FEC is deprecated and is retained only for backward - compatibility. Implementations of LSP ping SHOULD accept and process - this TLV, but SHOULD send LSP ping echo requests with the new TLV - (see next section), unless explicitly configured to use the old TLV. - - An LSR receiving this TLV SHOULD use the source IP address of the LSP - echo request to infer the sender's PE address. + See Appendix A.1 for details 3.2.9. FEC 128 Pseudowire - IPv4 (Current) FEC 128 (0x80) is defined in [RFC4447], as are the terms PW ID (Pseudowire ID) and PW Type (Pseudowire Type). A PW ID is a non-zero 32-bit connection ID. The PW Type is a 15-bit number indicating the encapsulation type. It is carried right justified in the field below termed encapsulation type with the high-order bit set to zero. Both of these fields are treated in this protocol as opaque values. @@ -1076,207 +1052,29 @@ Sender's PE IPv6 Address: The source IP address of the target IPv6 LDP session. 16 octets. Remote PE IPv6 Address: The destination IP address of the target IPv6 LDP session. 16 octets. The other fields are the same as FEC 129 Pseudowire IPv4 in Section 3.2.10. -3.3. Downstream Mapping - - The Downstream Mapping object is a TLV that MAY be included in an - echo request message. Only one Downstream Mapping object may appear - in an echo request. The presence of a Downstream Mapping object is a - request that Downstream Mapping objects be included in the echo - reply. If the replying router is the destination of the FEC, then a - Downstream Mapping TLV SHOULD NOT be included in the echo reply. - Otherwise the replying router SHOULD include a Downstream Mapping - object for each interface over which this FEC could be forwarded. - For a more precise definition of the notion of "downstream", see - section 3.3.2, "Downstream Router and Interface". - - The Length is K + M + 4*N octets, where M is the Multipath Length, - and N is the number of Downstream Labels. Values for K are found in - the description of Address Type below. The Value field 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 - +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - | MTU | Address Type | DS Flags | - +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - | Downstream IP Address (4 or 16 octets) | - +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - | Downstream Interface Address (4 or 16 octets) | - +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - | Multipath Type| Depth Limit | Multipath Length | - +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - . . - . (Multipath Information) . - . . - +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - | Downstream Label | Protocol | - +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - . . - . . - . . - +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - | Downstream Label | Protocol | - +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - - Maximum Transmission Unit (MTU) - - The MTU is the size in octets of the largest MPLS frame (including - label stack) that fits on the interface to the Downstream LSR. - - Address Type - The Address Type indicates if the interface is numbered or - unnumbered. It also determines the length of the Downstream IP - Address and Downstream Interface fields. The resulting total for - the initial part of the TLV is listed in the table below as "K - Octets". The Address Type is set to one of the following values: - - Type # Address Type K Octets - ------ ------------ -------- - 1 IPv4 Numbered 16 - 2 IPv4 Unnumbered 16 - 3 IPv6 Numbered 40 - 4 IPv6 Unnumbered 28 - - DS Flags - - The DS Flags field is a bit vector with the following format: - - 0 1 2 3 4 5 6 7 - +-+-+-+-+-+-+-+-+ - | Rsvd(MBZ) |I|N| - +-+-+-+-+-+-+-+-+ - - Two flags are defined currently, I and N. The remaining flags MUST - be set to zero when sending and ignored on receipt. - - Flag Name and Meaning - ---- ---------------- - I Interface and Label Stack Object Request - - When this flag is set, it indicates that the replying - router SHOULD include an Interface and Label Stack - Object in the echo reply message. - - N Treat as a Non-IP Packet - - Echo request messages will be used to diagnose non-IP - flows. However, these messages are carried in IP - packets. For a router that alters its ECMP algorithm - based on the FEC or deep packet examination, this flag - requests that the router treat this as it would if the - determination of an IP payload had failed. - - Downstream IP Address and Downstream Interface Address - - IPv4 addresses and interface indices are encoded in 4 octets; IPv6 - addresses are encoded in 16 octets. - - If the interface to the downstream LSR is numbered, then the - Address Type MUST be set to IPv4 or IPv6, the Downstream IP - Address MUST be set to either the downstream LSR's Router ID or - the interface address of the downstream LSR, and the Downstream - Interface Address MUST be set to the downstream LSR's interface - address. - - If the interface to the downstream LSR is unnumbered, the Address - Type MUST be IPv4 Unnumbered or IPv6 Unnumbered, the Downstream IP - Address MUST be the downstream LSR's Router ID, and the Downstream - Interface Address MUST be set to the index assigned by the - upstream LSR to the interface. - - If an LSR does not know the IP address of its neighbor, then it - MUST set the Address Type to either IPv4 Unnumbered or IPv6 - Unnumbered. For IPv4, it must set the Downstream IP Address to - 127.0.0.1; for IPv6 the address is set to 0::1. In both cases, - the interface index MUST be set to 0. If an LSR receives an Echo - Request packet with either of these addresses in the Downstream IP - Address field, this indicates that it MUST bypass interface - verification but continue with label validation. - - If the originator of an Echo Request packet wishes to obtain - Downstream Mapping information but does not know the expected - label stack, then it SHOULD set the Address Type to either IPv4 - Unnumbered or IPv6 Unnumbered. For IPv4, it MUST set the - Downstream IP Address to 224.0.0.2; for IPv6 the address MUST be - set to FF02::2. In both cases, the interface index MUST be set to - 0. If an LSR receives an Echo Request packet with the all-routers - multicast address, then this indicates that it MUST bypass both - interface and label stack validation, but return Downstream - Mapping TLVs using the information provided. - - Multipath Type - - The following Multipath Types are defined: - - Key Type Multipath Information - --- ---------------- --------------------- - 0 no multipath Empty (Multipath Length = 0) - 2 IP address IP addresses - 4 IP address range low/high address pairs - 8 Bit-masked IP IP address prefix and bit mask - address set - 9 Bit-masked label set Label prefix and bit mask - - Type 0 indicates that all packets will be forwarded out this one - interface. - - Types 2, 4, 8, and 9 specify that the supplied Multipath - Information will serve to exercise this path. - - Depth Limit - - 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. - - Multipath Length - - The length in octets of the Multipath Information. - - Multipath Information - - Address or label values encoded according to the Multipath Type. - See the next section below for encoding details. - - Downstream Label(s) - - The set of labels in the label stack as it would have appeared if - this router were forwarding the packet through this interface. - Any Implicit Null labels are explicitly included. Labels are - treated as numbers, i.e., they are right justified in the field. +3.3. Downstream Mapping (Deprecated) - A Downstream Label is 24 bits, in the same format as an MPLS label - minus the TTL field, i.e., the MSBit of the label is bit 0, the - LSBit is bit 19, the Traffic Class (TC) bits are bits 20-22, and - bit 23 is the S bit. The replying router SHOULD fill in the TC - and S bits; the LSR receiving the echo reply MAY choose to ignore - these bits. Protocol + See Appendix A.2 for more details. - The Protocol is taken from the following table: +3.4. Downstream Detailed Mapping - Protocol # Signaling Protocol - ---------- ------------------ - 0 Unknown - 1 Static - 2 BGP - 3 LDP - 4 RSVP-TE + The format of this TLV is defined in section 3.3 of [RFC6424] -3.3.1. Multipath Information Encoding +3.4.1. Multipath Information Encoding The Multipath Information encodes labels or addresses that will exercise this path. The Multipath Information depends on the Multipath Type. The contents of the field are shown in the table above. IPv4 addresses are drawn from the range 127/8; IPv6 addresses are drawn from the range 0:0:0:0:0:FFFF:7F00/104. Labels are treated as numbers, i.e., they are right justified in the field. For Type 4, ranges indicated by Address pairs MUST NOT overlap and MUST be in ascending sequence. @@ -1346,95 +1144,102 @@ Multipath Information is null (i.e., Multipath Length = 0, or for Types 8 and 9, a mask of all zeros), the type MUST be set to 0. For example, suppose LSR X at hop 10 has two downstream LSRs, Y and Z, for the FEC in question. The received X could return Multipath Type 4, with low/high IP addresses of 127.1.1.1->127.1.1.255 for downstream LSR Y and 127.2.1.1->127.2.1.255 for downstream LSR Z. The head end reflects this information to LSR Y. Y, which has three downstream LSRs, U, V, and W, computes that 127.1.1.1->127.1.1.127 would go to U and 127.1.1.128-> 127.1.1.255 would go to V. Y would - then respond with 3 Downstream Mappings: to U, with Multipath Type 4 - (127.1.1.1->127.1.1.127); to V, with Multipath Type 4 - (127.1.1.127->127.1.1.255); and to W, with Multipath Type 0. + then respond with 3 "Downstream Detailed Mapping" TLVs: to U, with + Multipath Type 4 (127.1.1.1->127.1.1.127); to V, with Multipath Type + 4 (127.1.1.127->127.1.1.255); and to W, with Multipath Type 0. Note that computing Multipath Information may impose a significant processing burden on the receiver. A receiver MAY thus choose to process a subset of the received prefixes. The sender, on receiving - a reply to a Downstream Mapping with partial information, SHOULD - assume that the prefixes missing in the reply were skipped by the - receiver, and MAY re-request information about them in a new echo + a reply to a Downstream Detailed Mapping with partial information, + SHOULD assume that the prefixes missing in the reply were skipped by + the receiver, and MAY re-request information about them in a new echo request. -3.3.2. Downstream Router and Interface + The encoding of Multipath information in scenarios where few LSRs + apply Entropy label based load balancing while other LSRs are non-EL + (IP based) load balancing will be defined in a different document. + + The encoding of multipath information in scenarios where LSR have + Layer 2 ECMP over Link Aggregation Group (LAG) interfaces will be + defined in different document. + +3.4.2. Downstream Router and Interface 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 and TTL=1 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 consists of 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. + Downstream Detailed Mapping to be added to the reply. The case where X is the LSR originating the echo request is a special 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 Information is used as a hint to the sender as to how it may influence the choice of these alternatives. -3.4. Pad TLV +3.5. 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 ----- ------- 1 Drop Pad TLV from reply 2 Copy Pad TLV to reply 3-255 Reserved for future use -3.5. Vendor Enterprise Number +3.6. Vendor Enterprise Number SMI Private Enterprise Numbers are maintained by IANA. The Length is always 4; the value is the SMI Private Enterprise code, in network octet order, of the vendor with a Vendor Private extension to any of the fields in the fixed part of the message, in which case this TLV MUST be present. If none of the fields in the fixed part of the message have Vendor Private extensions, inclusion of this TLV is OPTIONAL. Vendor Private ranges for Message Types, Reply Modes, and Return Codes have been defined. When any of these are used, the Vendor Enterprise Number TLV MUST be included in the message. -3.6. Interface and Label Stack +3.7. Interface and Label Stack The Interface and Label Stack TLV MAY be included in a reply message to report the interface on which the request message was received and the label stack that was on the packet when it was received. Only one such object may appear. The purpose of the object is to allow the upstream router to obtain the exact interface and label stack information as it appears at the replying LSR. The Length is K + 4*N octets; N is the number of labels in the label stack. Values for K are found in the description of Address Type - below. The Value field of a Downstream Mapping has the following - format: + below. The Value field of this TLV 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Address Type | Must Be Zero | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | IP Address (4 or 16 octets) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Interface (4 or 16 octets) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ @@ -1474,42 +1280,42 @@ If the interface is unnumbered, the Address Type MUST be either IPv4 Unnumbered or IPv6 Unnumbered, the IP Address MUST be the LSR's Router ID, and the Interface MUST be set to the index assigned to the interface. Label Stack The label stack of the received echo request message. If any TTL values have been changed by this router, they SHOULD be restored. -3.7. Errored TLVs +3.8. Errored TLVs The following TLV is a TLV that MAY be included in an echo reply to inform the sender of an echo request of mandatory TLVs either not supported by an implementation or parsed and found to be in error. The Value field contains the TLVs that were not understood, encoded as sub-TLVs. 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type = 9 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Value | . . . . . . | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ -3.8. Reply TOS Byte TLV +3.9. Reply TOS Byte TLV This TLV MAY be used by the originator of the echo request to request that an echo reply be sent with the IP header TOS byte set to the value specified in the TLV. This TLV has a length of 4 with the following value field. 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Reply-TOS Byte| Must Be Zero | @@ -1558,28 +1364,28 @@ 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, although 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 latitude 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 latitude is offered by means of the - Multipath Information 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 - downstream paths 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. + Multipath Information of the Downstream Detailed 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 downstream paths 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. Testing LSPs That Are Used to Carry MPLS Payloads To detect certain LSP breakages, it may be necessary to encapsulate an MPLS echo request packet with at least one additional label when testing LSPs that are used to carry MPLS payloads (such as LSPs used to carry L2VPN and L3VPN traffic. For example, when testing LDP or RSVP-TE LSPs, just sending an MPLS echo request packet may not detect instances where the router immediately upstream of the destination of the LSP ping may forward the MPLS echo request successfully over an @@ -1630,21 +1436,21 @@ 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. The TimeStamp Sent is set to the time-of-day in NTP format that the echo request is sent. The TimeStamp Received is set to zero. An MPLS echo request MUST have an 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 include a Downstream Mapping TLV. + SHOULD include a Downstream Detailed Mapping TLV. 4.4. Receiving an MPLS Echo Request Sending an MPLS echo request to the control plane is triggered by one of the following packet processing exceptions: Router Alert option, IP TTL expiration, MPLS TTL expiration, MPLS Router Alert label, or the destination address in the 127/8 address range. The control plane further identifies it by UDP destination port 3503. For reporting purposes the bottom of stack is considered to be stack- @@ -1671,22 +1477,23 @@ Handle, Sequence Number, and Timestamp Sent are not examined, but are included in the MPLS echo reply message. The algorithm uses the following variables and identifiers: Interface-I: the interface on which the MPLS echo request was received. Stack-R: the label stack on the packet as it was received. - Stack-D: the label stack carried in the Downstream Mapping - TLV (not always present) + Stack-D: the label stack carried in the "Label Stack sub- + TLV" in Downstream Detailed Mapping TLV (not + always present) Label-L: the label from the actual stack currently being examined. Requires no initialization. Label-stack-depth: the depth of label being verified. Initialized to the number of labels in the received label stack S. FEC-stack-depth: depth of the FEC in the Target FEC Stack that should be used to verify the current actual @@ -1766,41 +1572,41 @@ } If the label operation is "Swap or Pop and Switch based on Popped Label" { Set Best-return-code to 8 ("Label switched at stack-depth") and Best-rtn-subcode to Label-stack-depth to report transit switching. - If a Downstream Mapping TLV is present in the received echo - request { + If a Downstream Detailed Mapping TLV is present in the received + echo request { If the IP address in the TLV is 127.0.0.1 or 0::1 { Set Best-return-code to 6 ("Upstream Interface Index Unknown"). An Interface and Label Stack TLV SHOULD be included in the reply and filled with Interface-I and Stack-R. } Else { Verify that the IP address, interface address, and label - stack in the Downstream Mapping TLV match Interface-I and - Stack-R. If there is a mismatch, set Best-return-code to - 5, "Downstream Mapping Mismatch". An Interface and Label - Stack TLV SHOULD be included in the reply and filled in - based on Interface-I and Stack-R. Go to step 7 (Send - Reply Packet). + stack in the Downstream Detailed Mapping TLV match + Interface-I and Stack-R. If there is a mismatch, set + Best-return-code to 5, "Downstream Mapping Mismatch". An + Interface and Label Stack TLV SHOULD be included in the + reply and filled in based on Interface-I and Stack-R. Go + to step 7 (Send Reply Packet). } } For each available downstream ECMP path { Retrieve output interface from the NHLFE entry. /* Note: this return code is set even if Label-stack-depth @@ -1800,55 +1606,55 @@ } For each available downstream ECMP path { Retrieve output interface from the NHLFE entry. /* Note: this return code is set even if Label-stack-depth is one */ If the output interface is not MPLS enabled { - Set Best-return-code to Return Code 9, "Label switched but no MPLS forwarding at stack-depth" and set Best-rtn- subcode to Label-stack-depth and goto Send_Reply_Packet. } - If a Downstream Mapping TLV is present { + If a Downstream Detailed Mapping TLV is present { - A Downstream Mapping TLV SHOULD be included in the echo - reply (see section 3.3) filled in with information about - the current ECMP path. + A Downstream Detailed Mapping TLV SHOULD be included in + the echo reply (see Section 3.4) filled in with + information about the current ECMP path. } } - If no Downstream Mapping TLV is present, or the Downstream IP - Address is set to the ALLROUTERS multicast address, go to step - 7 (Send Reply Packet). + If no Downstream Detailed Mapping TLV is present, or the + Downstream IP Address is set to the ALLROUTERS multicast + address, go to step 7 (Send Reply Packet). If the "Validate FEC Stack" flag is not set and the LSR is not configured to perform FEC checking by default, go to step 7 (Send Reply Packet). /* Validate the Target FEC Stack in the received echo request. - First determine FEC-stack-depth from the Downstream Mapping - TLV. This is done by walking through Stack-D (the Downstream - labels) from the bottom, decrementing the number of labels for - each non-Implicit Null label, while incrementing FEC-stack- - depth for each label. If the Downstream Mapping TLV contains - one or more Implicit Null labels, FEC-stack-depth may be - greater than Label-stack-depth. To be consistent with the - above stack-depths, the bottom is considered to be entry 1. + First determine FEC-stack-depth from the Downstream Detailed + Mapping TLV. This is done by walking through Stack-D (the + Downstream labels) from the bottom, decrementing the number of + labels for each non-Implicit Null label, while incrementing + FEC-stack-depth for each label. If the Downstream Detailed + Mapping TLV contains one or more Implicit Null labels, FEC- + stack-depth may be greater than Label-stack-depth. To be + consistent with the above stack-depths, the bottom is + considered to be entry 1. */ Set FEC-stack-depth to 0. Set i to Label-stack-depth. While (i > 0 ) do { ++FEC-stack-depth. if Stack-D[FEC-stack-depth] != 3 (Implicit Null) --i. } @@ -1866,28 +1672,28 @@ } Go to step 7 (Send Reply Packet). } 5. Egress Processing: /* These steps are performed by the LSR that identified itself as the tail-end LSR for an LSP. */ - If received echo request contains no Downstream Mapping TLV, or - the Downstream IP Address is set to 127.0.0.1 or 0::1 go to step 6 - (Egress FEC Validation). + If received echo request contains no Downstream Detailed Mapping + TLV, or the Downstream IP Address is set to 127.0.0.1 or 0::1 go + to step 6 (Egress FEC Validation). Verify that the IP address, interface address, and label stack in - the Downstream Mapping TLV match Interface-I and Stack-R. If not, - set Best-return-code to 5, "Downstream Mapping Mis-match". A - Received Interface and Label Stack TLV SHOULD be created for the + the Downstream Detailed Mapping TLV match Interface-I and Stack-R. + If not, set Best-return-code to 5, "Downstream Mapping Mis-match". + A Received Interface and Label Stack TLV SHOULD be created for the echo response packet. Go to step 7 (Send Reply Packet). 6. Egress FEC Validation: /* This is a loop for all entries in the Target FEC Stack starting with FEC-stack-depth. */ Perform FEC checking by following the algorithm described in subsection 4.4.1 for Label-L and the FEC at FEC-stack-depth. @@ -1986,53 +1792,54 @@ 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 replying router is the destination of the FEC, then Downstream - Mapping TLVs SHOULD NOT be included in the echo reply. + Detailed Mapping TLVs SHOULD NOT be included in the echo reply. - If the echo request contains a Downstream Mapping TLV, and the - replying router is not the destination of the FEC, 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. + If the echo request contains a Downstream Detailed Mapping TLV, and + the replying router is not the destination of the FEC, the replier + SHOULD compute its downstream routers and corresponding labels for + the incoming label, and add Downstream Detailed Mapping TLVs for each + one to the echo reply it sends back. - If the Downstream Mapping TLV contains Multipath Information + If the Downstream Detailed Mapping TLV contains Multipath Information requiring more processing than the receiving router is willing to perform, the responding router MAY choose to respond with only a subset of multipaths contained in the echo request Downstream - Mapping. (Note: The originator of the echo request MAY send another - echo request with the Multipath Information that was not included in - the reply.) + Detailed Mapping. (Note: The originator of the echo request MAY send + another echo request with the Multipath Information that was not + included in the reply.) Except in the case of Reply Mode 4, "Reply via application level control channel", echo replies are always sent in the context of the IP/MPLS network. 4.6. 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 ensure 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. - If the echo reply contains Downstream Mappings, and X wishes to - traceroute further, it SHOULD copy the Downstream Mapping(s) into its - next echo request(s) (with TTL incremented by one). + If the echo reply contains Downstream Detailed Mappings, and X wishes + to traceroute further, it SHOULD copy the Downstream Detailed + Mapping(s) into its next echo request(s) (with TTL incremented by + one). 4.7. Issue with VPN IPv4 and IPv6 Prefixes Typically, an LSP ping for a VPN IPv4 prefix or VPN IPv6 prefix is sent with a label stack of depth greater than 1, with the innermost label having a TTL of 1. This is to terminate the ping at the egress PE, before it gets sent to the customer device. However, under certain circumstances, the label stack can shrink to a single label before the ping hits the egress PE; this will result in the ping terminating prematurely. One such scenario is a multi-AS Carrier's @@ -2047,26 +1854,26 @@ 4.8. 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 LSP 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 to probe LSRs further down the path. In such a case, the echo request for TTL > n SHOULD - be sent with Downstream Mapping TLV "Downstream IP Address" field set - to the ALLROUTERs multicast address until a reply is received with a - Downstream Mapping TLV. The label stack MAY be omitted from the - Downstream Mapping TLV. Furthermore, the "Validate FEC Stack" flag - SHOULD NOT be set until an echo reply packet with a Downstream - Mapping TLV is received. + be sent with Downstream Detailed Mapping TLV "Downstream IP Address" + field set to the ALLROUTERs multicast address until a reply is + received with a Downstream Detailed Mapping TLV. The label stack TLV + MAY be omitted from the Downstream Detailed Mapping TLV. + Furthermore, the "Validate FEC Stack" flag SHOULD NOT be set until an + echo reply packet with a Downstream Detailed Mapping TLV is received. 5. Security Considerations Overall, the security needs for LSP ping are similar to those of ICMP ping. There are at least three approaches to attacking LSRs using the mechanisms defined here. One is a Denial-of-Service attack, by sending MPLS echo requests/replies to LSRs and thereby increasing their workload. The second is obfuscating the state of the MPLS data @@ -2230,22 +2037,24 @@ This document is the outcome of many discussions among many people, including Manoj Leelanivas, Paul Traina, Yakov Rekhter, Der-Hwa Gan, Brook Bailey, Eric Rosen, Ina Minei, Shivani Aggarwal, and Vanson Lim. The description of the Multipath Information sub-field of the Downstream Mapping TLV was adapted from text suggested by Curtis Villamizar. We would like to thank Loa Andersson for motivating the advancement - of this bis specification. We also would like to thank Alexander - Vainshtein for his review and comments. + of this bis specification. + + We also would like to thank Alexander Vainshtein, Yimin Shen, Curtis + Villamizar, David Allan for their review and comments. 8. References 8.1. Normative References [RFC1122] Braden, R., Ed., "Requirements for Internet Hosts - Communication Layers", STD 3, RFC 1122, DOI 10.17487/RFC1122, October 1989, . @@ -2285,20 +2094,25 @@ [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA Considerations Section in RFCs", BCP 26, RFC 5226, DOI 10.17487/RFC5226, May 2008, . [RFC5905] Mills, D., Martin, J., Ed., Burbank, J., and W. Kasch, "Network Time Protocol Version 4: Protocol and Algorithms Specification", RFC 5905, DOI 10.17487/RFC5905, June 2010, . + [RFC6424] Bahadur, N., Kompella, K., and G. Swallow, "Mechanism for + Performing Label Switched Path Ping (LSP Ping) over MPLS + Tunnels", RFC 6424, DOI 10.17487/RFC6424, November 2011, + . + [RFC7506] Raza, K., Akiya, N., and C. Pignataro, "IPv6 Router Alert Option for MPLS Operations, Administration, and Maintenance (OAM)", RFC 7506, DOI 10.17487/RFC7506, April 2015, . 8.2. Informative References [RFC0792] Postel, J., "Internet Control Message Protocol", STD 5, RFC 792, DOI 10.17487/RFC0792, September 1981, . @@ -2330,27 +2144,246 @@ [RFC5036] Andersson, L., Ed., Minei, I., Ed., and B. Thomas, Ed., "LDP Specification", RFC 5036, DOI 10.17487/RFC5036, October 2007, . [RFC5085] Nadeau, T., Ed. and C. Pignataro, Ed., "Pseudowire Virtual Circuit Connectivity Verification (VCCV): A Control Channel for Pseudowires", RFC 5085, DOI 10.17487/RFC5085, December 2007, . +Appendix A. Deprecated TLVs + +A.1. FEC 128 Pseudowire + + FEC 128 (0x80) is defined in [RFC4447], as are the terms PW ID + (Pseudowire ID) and PW Type (Pseudowire Type). A PW ID is a non-zero + 32-bit connection ID. The PW Type is a 15-bit number indicating the + encapsulation type. It is carried right justified in the field below + termed encapsulation type with the high-order bit set to zero. Both + of these fields are treated in this protocol as opaque values. + + When an FEC 128 is encoded in a label stack, the following format is + used. The value field consists of the remote PE IPv4 address (the + destination address of the targeted LDP session), the PW ID, and the + 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 + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | Remote PE IPv4 Address | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | PW ID | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | PW Type | Must Be Zero | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + + This FEC is deprecated and is retained only for backward + compatibility. Implementations of LSP ping SHOULD accept and process + this TLV, but SHOULD send LSP ping echo requests with the new TLV + (see next section), unless explicitly configured to use the old TLV. + + An LSR receiving this TLV SHOULD use the source IP address of the LSP + echo request to infer the sender's PE address. + +A.2. Downstream Mapping(DSMAP) + + The Downstream Mapping object is a TLV that MAY be included in an + echo request message. Only one Downstream Mapping object may appear + in an echo request. The presence of a Downstream Mapping object is a + request that Downstream Mapping objects be included in the echo + reply. If the replying router is the destination of the FEC, then a + Downstream Mapping TLV SHOULD NOT be included in the echo reply. + Otherwise the replying router SHOULD include a Downstream Mapping + object for each interface over which this FEC could be forwarded. + For a more precise definition of the notion of "downstream", see + section 3.3.2, "Downstream Router and Interface". + + The Length is K + M + 4*N octets, where M is the Multipath Length, + and N is the number of Downstream Labels. Values for K are found in + the description of Address Type below. The Value field 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 + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | MTU | Address Type | DS Flags | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | Downstream IP Address (4 or 16 octets) | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | Downstream Interface Address (4 or 16 octets) | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | Multipath Type| Depth Limit | Multipath Length | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + . . + . (Multipath Information) . + . . + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | Downstream Label | Protocol | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + . . + . . + . . + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + | Downstream Label | Protocol | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + + Maximum Transmission Unit (MTU) + + The MTU is the size in octets of the largest MPLS frame (including + label stack) that fits on the interface to the Downstream LSR. + + Address Type + The Address Type indicates if the interface is numbered or + unnumbered. It also determines the length of the Downstream IP + Address and Downstream Interface fields. The resulting total for + the initial part of the TLV is listed in the table below as "K + Octets". The Address Type is set to one of the following values: + + Type # Address Type K Octets + ------ ------------ -------- + 1 IPv4 Numbered 16 + 2 IPv4 Unnumbered 16 + 3 IPv6 Numbered 40 + 4 IPv6 Unnumbered 28 + + DS Flags + + The DS Flags field is a bit vector with the following format: + + 0 1 2 3 4 5 6 7 + +-+-+-+-+-+-+-+-+ + | Rsvd(MBZ) |I|N| + +-+-+-+-+-+-+-+-+ + + Two flags are defined currently, I and N. The remaining flags MUST + be set to zero when sending and ignored on receipt. + + Flag Name and Meaning + ---- ---------------- + I Interface and Label Stack Object Request + + When this flag is set, it indicates that the replying + router SHOULD include an Interface and Label Stack + Object in the echo reply message. + + N Treat as a Non-IP Packet + + Echo request messages will be used to diagnose non-IP + flows. However, these messages are carried in IP + packets. For a router that alters its ECMP algorithm + based on the FEC or deep packet examination, this flag + requests that the router treat this as it would if the + determination of an IP payload had failed. + + Downstream IP Address and Downstream Interface Address + + IPv4 addresses and interface indices are encoded in 4 octets; IPv6 + addresses are encoded in 16 octets. + + If the interface to the downstream LSR is numbered, then the + Address Type MUST be set to IPv4 or IPv6, the Downstream IP + Address MUST be set to either the downstream LSR's Router ID or + the interface address of the downstream LSR, and the Downstream + Interface Address MUST be set to the downstream LSR's interface + address. + + If the interface to the downstream LSR is unnumbered, the Address + Type MUST be IPv4 Unnumbered or IPv6 Unnumbered, the Downstream IP + Address MUST be the downstream LSR's Router ID, and the Downstream + Interface Address MUST be set to the index assigned by the + upstream LSR to the interface. + + If an LSR does not know the IP address of its neighbor, then it + MUST set the Address Type to either IPv4 Unnumbered or IPv6 + Unnumbered. For IPv4, it must set the Downstream IP Address to + 127.0.0.1; for IPv6 the address is set to 0::1. In both cases, + the interface index MUST be set to 0. If an LSR receives an Echo + Request packet with either of these addresses in the Downstream IP + Address field, this indicates that it MUST bypass interface + verification but continue with label validation. + + If the originator of an Echo Request packet wishes to obtain + Downstream Mapping information but does not know the expected + label stack, then it SHOULD set the Address Type to either IPv4 + Unnumbered or IPv6 Unnumbered. For IPv4, it MUST set the + Downstream IP Address to 224.0.0.2; for IPv6 the address MUST be + set to FF02::2. In both cases, the interface index MUST be set to + 0. If an LSR receives an Echo Request packet with the all-routers + multicast address, then this indicates that it MUST bypass both + interface and label stack validation, but return Downstream + Mapping TLVs using the information provided. + + Multipath Type + + The following Multipath Types are defined: + + Key Type Multipath Information + --- ---------------- --------------------- + 0 no multipath Empty (Multipath Length = 0) + 2 IP address IP addresses + 4 IP address range low/high address pairs + 8 Bit-masked IP IP address prefix and bit mask + address set + 9 Bit-masked label set Label prefix and bit mask + + Type 0 indicates that all packets will be forwarded out this one + interface. + + Types 2, 4, 8, and 9 specify that the supplied Multipath + Information will serve to exercise this path. + + Depth Limit + + 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. + + Multipath Length + + The length in octets of the Multipath Information. + + Multipath Information + + Address or label values encoded according to the Multipath Type. + See the next section below for encoding details. + + Downstream Label(s) + + The set of labels in the label stack as it would have appeared if + this router were forwarding the packet through this interface. + Any Implicit Null labels are explicitly included. Labels are + treated as numbers, i.e., they are right justified in the field. + + A Downstream Label is 24 bits, in the same format as an MPLS label + minus the TTL field, i.e., the MSBit of the label is bit 0, the + LSBit is bit 19, the Traffic Class (TC) bits are bits 20-22, and + bit 23 is the S bit. The replying router SHOULD fill in the TC + and S bits; the LSR receiving the echo reply MAY choose to ignore + these bits. Protocol + + The Protocol is taken from the following table: + + Protocol # Signaling Protocol + ---------- ------------------ + 0 Unknown + 1 Static + 2 BGP + 3 LDP + 4 RSVP-TE + Authors' Addresses Kireeti Kompella Juniper Networks, Inc. Email: kireeti.kompella@gmail.com - Carlos Pignataro Cisco Systems, Inc. Email: cpignata@cisco.com Nagendra Kumar Cisco Systems, Inc. Email: naikumar@cisco.com