draft-ietf-mpls-lsp-ping-02.txt   draft-ietf-mpls-lsp-ping-03.txt 
Network Working Group K. Kompella (Juniper) Network Working Group K. Kompella (Juniper)
Internet Draft P. Pan (Ciena) Internet Draft P. Pan (Ciena)
draft-ietf-mpls-lsp-ping-02.txt N. Sheth (Juniper) draft-ietf-mpls-lsp-ping-03.txt N. Sheth (Juniper)
Category: Standards Track D. Cooper (Global Crossing) Category: Standards Track D. Cooper (Global Crossing)
Expires: September 2003 G. Swallow (Cisco) Expires: December 2003 G. Swallow (Cisco)
S. Wadhwa (Juniper) S. Wadhwa (Juniper)
R. Bonica (WorldCom) R. Bonica (WorldCom)
March 2003 June 2003
Detecting MPLS Data Plane Liveness Detecting MPLS Data Plane Failures
*** DRAFT *** *** DRAFT ***
Status of this Memo Status of this Memo
This document is an Internet-Draft and is in full conformance with This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC2026. all provisions of Section 10 of RFC2026.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that Task Force (IETF), its areas, and its working groups. Note that
skipping to change at page 2, line 14 skipping to change at page 2, line 14
Abstract Abstract
This document describes a simple and efficient mechanism that can be This document describes a simple and efficient mechanism that can be
used to detect data plane failures in Multi-Protocol Label Switching used to detect data plane failures in Multi-Protocol Label Switching
(MPLS) Label Switched Paths (LSPs). There are two parts to this (MPLS) Label Switched Paths (LSPs). There are two parts to this
document: information carried in an MPLS "echo request" and "echo document: information carried in an MPLS "echo request" and "echo
reply" for the purposes of fault detection and isolation; and reply" for the purposes of fault detection and isolation; and
mechanisms for reliably sending the echo reply. mechanisms for reliably sending the echo reply.
Sub-IP ID Summary Changes since last revision
(This section to be removed before publication.) (This section to be removed before publication.)
(See Abstract above.) - Changed title to "Detecting MPLS Data Plane Failures"
- removed section 5 "Reliable Reply Path"
RELATED DOCUMENTS - filled in IANA section
- added new top level TLV for Vendor Enterprise Code
May be found in the "references" section. - Clarified Downstream Router ID and Downstream Interface Address
- Clarified receiving procedure
WHERE DOES IT FIT IN THE PICTURE OF THE SUB-IP WORK - Example for multipath operation
Fits in the MPLS box.
WHY IS IT TARGETED AT THIS WG
MPLS WG is currently looking at MPLS-specific error detection and Issues
recovery mechanisms. The mechanisms proposed here are for packet-
based MPLS LSPs, which is why the MPLS WG is targeted.
JUSTIFICATION (This section to be removed before publication.)
The WG should consider this document, as it allows network operators - Question: use two bits from the TLV space to indicate
to detect MPLS LSP data plane failures in the network. This type of - Ignore TLV if not understood
failures have occurred, and are a source of concern to operators - Reflect TLV in reply
implementing MPLS networks. - Tweak error codes? Add stack depth?
- More multipath stuff?
1. Introduction 1. Introduction
This document describes a simple and efficient mechanism that can be This document describes a simple and efficient mechanism that can be
used to detect data plane failures in MPLS LSPs. There are two parts used to detect data plane failures in MPLS LSPs. There are two parts
to this document: information carried in an MPLS "echo request" and to this document: information carried in an MPLS "echo request" and
"echo reply"; and mechanisms for transporting the echo reply. The "echo reply"; and mechanisms for transporting the echo reply. The
first part aims at providing enough information to check correct first part aims at providing enough information to check correct
operation of the data plane, as well as a mechanism to verify the operation of the data plane, as well as a mechanism to verify the
data plane against the control plane, and thereby localize faults. data plane against the control plane, and thereby localize faults.
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The body of this memo contains four main parts: motivation, MPLS echo The body of this memo contains four main parts: motivation, MPLS echo
request/reply packet format, MPLS ping operation, and a reliable request/reply packet format, MPLS ping operation, and a reliable
return path. It is suggested that first-time readers skip the actual return path. It is suggested that first-time readers skip the actual
packet formats and read the Theory of Operation first; the document packet formats and read the Theory of Operation first; the document
is structured the way it is to avoid forward references. is structured the way it is to avoid forward references.
The last section (reliable return path for RSVP LSPs) may be removed The last section (reliable return path for RSVP LSPs) may be removed
in a future revision. in a future revision.
1.3. Changes since last revision
(This section to be removed before publication.)
- 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 2. Motivation
When an LSP fails to deliver user traffic, the failure cannot always 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 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 tool that would enable users to detect such traffic "black holes" or
misrouting within a reasonable period of time; and a mechanism to misrouting within a reasonable period of time; and a mechanism to
isolate faults. isolate faults.
In this document, we describe a mechanism that accomplishes these In this document, we describe a mechanism that accomplishes these
goals. This mechanism is modeled after the ping/traceroute paradigm: goals. This mechanism is modeled after the ping/traceroute paradigm:
skipping to change at page 6, line 17 skipping to change at page 6, line 10
1 MPLS Echo Request 1 MPLS Echo Request
2 MPLS Echo Reply 2 MPLS Echo Reply
The Reply Mode can take one of the following values: The Reply Mode can take one of the following values:
Value Meaning Value Meaning
----- ------- ----- -------
1 Do not reply 1 Do not reply
2 Reply via an IPv4 UDP packet 2 Reply via an IPv4 UDP packet
3 Reply via an IPv4 UDP packet with Router Alert 3 Reply via an IPv4 UDP packet with Router Alert
4 Reply via the control plane
An MPLS echo request with "Do not reply" may be used for one-way 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 connectivity tests; the receiving router may log gaps in the sequence
numbers and/or maintain delay/jitter statistics. An MPLS echo numbers and/or maintain delay/jitter statistics. An MPLS echo
request would normally have "Reply via an IPv4 UDP packet"; if the request would normally have "Reply via an IPv4 UDP packet"; if the
normal IPv4 return path is deemed unreliable, one may use "Reply via normal IPv4 return path is deemed unreliable, one may use "Reply via
an IPv4 UDP packet with Router Alert" (note that this requires that an IPv4 UDP packet with Router Alert" (note that this requires that
all intermediate routers understand and know how to forward MPLS echo all intermediate routers understand and know how to forward MPLS echo
replies) or "Reply via the control plane" (this is currently only replies).
defined for control plane that uses RSVP).
The Return Code is set to zero by the sender. The receiver can set The Return Code is set to zero by the sender. The receiver can set
it to one of the following values: it to one of the following values:
Value Meaning Value Meaning
----- ------- ----- -------
0 The error code is contained in the Error Code TLV 0 The error code is contained in the Error Code TLV
1 Malformed echo request received 1 Malformed echo request received
2 One or more of the TLVs was not understood 2 One or more of the TLVs was not understood
3 Replying router is an egress for the FEC 3 Replying router is an egress for the FEC
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Types are defined below; Length is the length of the Value field in 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 octets. The Value field depends on the Type; it is zero padded to
align to a four-octet boundary. align to a four-octet boundary.
Type # Value Field Type # Value Field
------ ----------- ------ -----------
1 Target FEC Stack 1 Target FEC Stack
2 Downstream Mapping 2 Downstream Mapping
3 Pad 3 Pad
4 Error Code 4 Error Code
5 Vendor Enterprise Code
3.1. Target FEC Stack 3.1. Target FEC Stack
A Target FEC Stack is a list of sub-TLVs. The number of elements is A Target FEC Stack is a list of sub-TLVs. The number of elements is
determined by the looking at the sub-TLV length fields. determined by the looking at the sub-TLV length fields.
Sub-Type # Length Value Field Sub-Type # Length Value Field
---------- ------ ----------- ---------- ------ -----------
1 5 LDP IPv4 prefix 1 5 LDP IPv4 prefix
2 17 LDP IPv6 prefix 2 17 LDP IPv6 prefix
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corresponding to the top of the label stack, etc. corresponding to the top of the label stack, etc.
An MPLS echo request MUST have a Target FEC Stack that describes the 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 FEC stack being tested. For example, if an LSR X has an LDP mapping
for 192.168.1.1 (say label 1001), then to verify that label 1001 does 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 indeed reach an egress LSR that announced this prefix via LDP, X can
send an MPLS echo request with a FEC Stack TLV with one FEC in it, send an MPLS echo request with a FEC Stack TLV with one FEC in it,
namely of type LDP IPv4 prefix, with prefix 192.168.1.1/32, and send namely of type LDP IPv4 prefix, with prefix 192.168.1.1/32, and send
the echo request with a label of 1001. the echo request with a label of 1001.
If LSR X wanted to verify that a label stack of <1001, 23456> is the Say LSR X wanted to verify that a label stack of <1001, 23456> is the
right label stack to use to reach an IP VPN prefix of 10/8 in VPN foo right label stack to use to reach a VPN IPv4 prefix of 10/8 in VPN
on an egress LSR with loopback address 192.168.1.1 (learned via LDP), foo. Say further that LSR Y with loopback address 192.168.1.1
X has two choices. X can send an MPLS echo request with a FEC Stack announced prefix 10/8 with Route Distinguisher RD-foo-Y (which may in
TLV with a single FEC of type VPN IPv4 prefix with a prefix of 10/8 general be different from the Route Distinguisher that LSR X uses in
with the Route Distinguisher for VPN foo. Alternatively, X can send its own advertisements for VPN foo), label 23456 and BGP nexthop
a FEC Stack TLV with two FECs, the first of type LDP IPv4 with a 192.168.1.1. Finally, suppose that LSR X receives a label binding of
prefix of 192.168.1.1/32 and the second of type of IP VPN with a 1001 for 192.168.1.1 via LDP. X has two choices in sending an MPLS
prefix 10/8 in VPN foo. In either case, the MPLS echo request would echo request: X can send an MPLS echo request with a FEC Stack TLV
have a label stack of <1001, 23456>. (Note: in this example, 1001 is with a single FEC of type VPN IPv4 prefix with a prefix of 10/8 and a
the "outer" label and 23456 is the "inner" label.) 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.)
3.1.1. LDP IPv4 Prefix 3.1.1. LDP IPv4 Prefix
The value consists of four octets of an IPv4 prefix followed by one 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 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. order. See [LDP] for an example of a Mapping for an IPv4 FEC.
3.1.2. LDP IPv6 Prefix 3.1.2. LDP IPv6 Prefix
The value consists of sixteen octets of an IPv6 prefix followed by The value consists of sixteen octets of an IPv6 prefix followed by
skipping to change at page 9, line 44 skipping to change at page 9, line 40
| IPv6 tunnel sender address | | IPv6 tunnel sender address |
| | | |
| | | |
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Must Be Zero | LSP ID | | Must Be Zero | LSP ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
3.1.5. VPN IPv4 Prefix 3.1.5. VPN IPv4 Prefix
The value field consists of a Route Distinguisher, an IPv4 prefix and The value field consists of the Route Distinguisher advertised with
a prefix length, as follows: the VPN IPv4 prefix, the IPv4 prefix and a prefix length, as follows:
0 1 2 3 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 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Route Distinguisher | | Route Distinguisher |
| (8 octets) | | (8 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv4 prefix | | IPv4 prefix |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Prefix Length | Must Be Zero | | Prefix Length | Must Be Zero |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
3.1.6. VPN IPv6 Prefix 3.1.6. VPN IPv6 Prefix
The value field consists of a Route Distinguisher, an IPv6 prefix and The value field consists of the Route Distinguisher advertised with
a prefix length, as follows: the VPN IPv6 prefix, the IPv6 prefix and a prefix length, as follows:
0 1 2 3 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 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Route Distinguisher | | Route Distinguisher |
| (8 octets) | | (8 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv6 prefix | | IPv6 prefix |
| | | |
| | | |
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| Remote PE Address | | Remote PE Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| VC ID | | VC ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Encapsulation Type | Must Be Zero | | Encapsulation Type | Must Be Zero |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
3.2. Downstream Mapping 3.2. Downstream Mapping
The Downstream Mapping is an optional TLV in an echo request. The 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 Length is 16 + 4*M + 4*N octets, where M is the Multipath Length, and
Labels. The Value of a Downstream Mapping has the following format: N is the number of Downstream Labels. The Value field of a
Downstream Mapping has the following format:
0 1 2 3 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 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 | | Downstream IPv4 Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MTU | Address Type | DS Index | | MTU | Address Type | DS Index |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Downstream Interface Address | | Downstream Interface Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Hash Key Type | Depth Limit | Multipath Length | | Hash Key Type | Depth Limit | No of Multipaths |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IP Address or Next Label | | IP Address or Next Label |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. . . .
. (more IP Addresses or Next Labels) . . (more IP Addresses or Next Labels) .
. . . .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Downstream Label | Protocol | | Downstream Label | Protocol |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. . . .
. . . .
. . . .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Downstream Label | Protocol | | Downstream Label | Protocol |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
If the interface to the downstream LSR is numbered, then the
Downstream IPv4 Address can either be the downstream LSR's Router ID
or the interface address of the downstream LSR. In this case, the
Address Type is set to IPv4 and the Downstream Interface Address is
set to the downstream LSR's interface address. If the interface to
the downstream LSR is unnumbered, the Downstream IPv4 Address MUST be
the downstream LSR's Router ID, and the Address Type MUST be
Unnumbered, and the Downstream Interface Address MUST be the index
assigned by the upstream LSR to the interface.
The MTU is the largest MPLS frame (including label stack) that fits The MTU is the largest MPLS frame (including label stack) that fits
on the interface to the Downstream LSR. The Downstream Interface on the interface to the Downstream LSR. The Downstream Interface
Address Type is one of: Address Type is one of:
Type # Address Type Type # Address Type
------ ------------ ------ ------------
1 IPv4 1 IPv4
2 Unnumbered 2 Unnumbered
'Protocol' is taken from the following table: 'Protocol' is taken from the following table:
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the incoming label L may be swapped with a label stack.) 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 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 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. 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 The set of downstream routers at X may be alternative paths (see the
discussion below on ECMP) or simultaneous paths (e.g., for MPLS discussion below on ECMP) or simultaneous paths (e.g., for MPLS
multicast). In the former case, the Multipath sub-field is used as a 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 hint to the sender as to how it may influence the choice of these
alternatives. The Multipath Length is the total length of the alternatives. The "No of Multipaths" is the number of IP
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
Address/Next Label fields). The Hash Key Type is taken from the
following table: following table:
Hash Key Type IP Address or Next Label Hash Key Type IP Address or Next Label
-------------------- ------------------------ -------------------- ------------------------
0 no multipath (nothing; M = 0) 0 no multipath (nothing; M = 0)
1 label M labels 1 label M labels
2 IP address M IP addresses 2 IP address M IP addresses
3 label range M/2 low/high label pairs 3 label range M/2 low/high label pairs
4 IP address range M/2 low/high address pairs 4 IP address range M/2 low/high address pairs
5 no more labels (nothing; M = 0) 5 no more labels (nothing; M = 0)
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maximum number of labels considered in the hash; this SHOULD be set maximum number of labels considered in the hash; this SHOULD be set
to zero if unspecified or unlimited. to zero if unspecified or unlimited.
IP Address or Next Label is an IP address from the range 127/8 or an IP Address or Next Label is an IP address from the range 127/8 or an
next label which will exercise this particular path. next label which will exercise this particular path.
The semantics of the Hash Key Type and IP Address/Next Label are as The semantics of the Hash Key Type and IP Address/Next Label are as
follows: follows:
type 1 - a list of single labels is provided, any one of which type 1 - a list of single labels is provided, any one of which
will will cause the hash to match this MP path.
cause the hash to match this MP path.
type 2 - a list of single IP addresses is provided, any one of type 2 - a list of single IP addresses is provided, any one of
which will cause the hash to match this MP path. which will cause the hash to match this MP path.
type 3 - a list of label ranges is provided, any one of which will type 3 - a list of label ranges is provided, any one of which will
cause the hash to match this MP path. cause the hash to match this MP path.
type 4 - a list of IP address ranges is provided, any one of which type 4 - a list of IP address ranges is provided, any one of which
will cause the hash to match this MP path. will cause the hash to match this MP path.
type 5 - if no more labels are provided on the stack, this MP path type 5 - if no more labels are provided on the stack, this MP path
will apply (can only appear once). will apply (can only appear once).
type 6 - Any IP addresses matches. Undertlying labels may go type 6 - Any IP addresses matches. Underlying labels may go
elsewhere, but all IP takes only one MP path (can only elsewhere, but all IP takes only one MP path (can only
appear once). appear once).
type 7 - no matches are possible given the set of "Multipath type 7 - no matches are possible given the set of "Multipath
Exercise TLV" provided by prior hops. Exercise TLV" provided by prior hops.
If prior hops provide a "Downstream Multipath Mapping TLV" the labels If prior hops provide a "Downstream Multipath Mapping TLV" the labels
and IP addresses should be picked from the set provided in prior and IP addresses should be picked from the set provided in prior
"Multipath Exercise TLV" or "Hash Key Type" of 7 used. "Multipath Exercise TLV" or "Hash Key Type" of 7 used.
For example, suppose LSR X at hop 10 has two downstream LSRs Y and Z
for the FEC in question. X could return Hash Key Type 4, with
low/high IP addresses of 1.1.1.1->1.1.1.255 for downstream LSR Y and
2.1.1.1->2.1.1.255 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 1.1.1.1->1.1.1.127 would go to U and 1.1.1.128->
1.1.1.255 would go to V. Y would then respond with 3 Downstream
Mappings: to U, with Hash Key Type 4 (1.1.1.1->1.1.1.127); to V, with
Hash Key Type 4 (1.1.1.127->1.1.1.255); and to W, with Hash Key Type
7.
3.3. Pad TLV 3.3. Pad TLV
The value part of the Pad TLV contains a variable number (>= 1) of The value part of the Pad TLV contains a variable number (>= 1) of
octets. The first octet takes values from the following table; all octets. The first octet takes values from the following table; all
the other octets (if any) are ignored. The receiver SHOULD verify the other octets (if any) are ignored. The receiver SHOULD verify
that the TLV is received in its entirety, but otherwise ignores the that the TLV is received in its entirety, but otherwise ignores the
contents of this TLV, apart from the first octet. contents of this TLV, apart from the first octet.
Value Meaning Value Meaning
----- ------- ----- -------
1 Drop Pad TLV from reply 1 Drop Pad TLV from reply
2 Copy Pad TLV to reply 2 Copy Pad TLV to reply
3-255 Reserved for future use 3-255 Reserved for future use
3.4. Error Code 3.4. Error Code
The Error Code TLV is currently not defined; its purpose is to The Error Code TLV is currently not defined; its purpose is to
provide a mechanism for a more elaborate error reporting structure, provide a mechanism for a more elaborate error reporting structure,
should the reason arise. should the reason arise.
3.5. Vendor Enterprise Code
The Length is always 4; the value is the SMI 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, this TLV is OPTIONAL.
4. Theory of Operation 4. Theory of Operation
An MPLS echo request is used to test a particular LSP. The LSP to be 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 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 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 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 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 FEC stack consists of a single element that captures the RSVP Session
and Sender Template which uniquely identifies the LSP. and Sender Template which uniquely identifies the LSP.
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possible paths. However, full coverage may not be possible. possible paths. However, full coverage may not be possible.
4.2. Sending an MPLS Echo Request 4.2. Sending an MPLS Echo Request
An MPLS echo request is a (possibly) labelled UDP packet. The IP 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 header is set as follows: the source IP address is a routable address
of the sender; the destination IP address is a (randomly chosen) 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 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 chosen by the sender; the destination UDP port is set to 3503
(assigned by IANA for MPLS echo requests). The Router Alert option (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 is set in the IP header.
TTL on all the labels except the outermost should be set to 1.
If the echo request is labelled, one may (depending on what is being
pinged) set the TTL of the innermost label to 1, to prevent the ping
request going farther than it should. Examples of this include
pinging a VPN IPv4 or IPv6 prefix, an L2 VPN end point or an L2
circuit ID. This can also be accomplished by inserting a router
alert label above this label; however, this may lead to the undesired
side effect that MPLS echo requests take a different data path than
actual data.
In "ping" mode (end-to-end connectivity check), the TTL in the In "ping" mode (end-to-end connectivity check), the TTL in the
outermost label is set to 255. In "traceroute" mode (fault isolation outermost label is set to 255. In "traceroute" mode (fault isolation
mode), the TTL is set successively to 1, 2, .... mode), the TTL is set successively to 1, 2, ....
The sender chooses a Sender's Handle, and a Sequence Number. When The sender chooses a Sender's Handle, and a Sequence Number. When
sending subsequent MPLS echo requests, the sender SHOULD increment sending subsequent MPLS echo requests, the sender SHOULD increment
the sequence number by 1. However, a sender MAY choose to send a 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 group of echo requests with the same sequence number to improve the
chance of arrival of at least one packet with that sequence number. chance of arrival of at least one packet with that sequence number.
skipping to change at page 16, line 25 skipping to change at page 17, line 9
An LSR X 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 to ensure that it is a well-formed packet, and that the TLVs are
understood. If not, X SHOULD send an MPLS echo reply with the Return understood. If not, X SHOULD send an MPLS echo reply with the Return
Code set to "Malformed echo request received" or "TLV not understood" Code set to "Malformed echo request received" or "TLV not understood"
(as appropriate), and the Subcode set to the appropriate value. (as appropriate), and the Subcode set to the appropriate value.
If the echo request is good, X then checks whether it is a valid 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 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 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 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 whether it actually advertised L for the FEC in the echo request; X
echo request. MAY further check whether it expects L over interface I or not.
If the echo request contains a Downstream Mapping TLV, X 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 check whether its Router ID or one of its interface addresses matches
IDs; and if so, whether the given Downstream Label is in fact the one of the Downstream IPv4 Address; if the Address Type is
label that X sent as its mapping for the FEC over the downstream Unnumbered, X further checks if the interface I has the given
interface. The result of the checks in the previous and this (upstream) index. If these check out, X determines whether the given
paragraph are captured in the Return Code/Subcode. Downstream Label is in fact the 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, X 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. procedure in the next subsection to send the echo reply.
4.4. 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 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 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 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 ping. The destination IP address and UDP port are copied from the
skipping to change at page 18, line 5 skipping to change at page 18, line 39
ping, then no reply will be sent, resulting in possible "false ping, then no reply will be sent, resulting in possible "false
negatives". If in "traceroute" mode, a transit LSR does not support negatives". If in "traceroute" mode, a transit LSR does not support
MPLS ping, then no reply will be forthcoming from that LSR for some 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 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 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 transit LSR further downstream may support MPLS echo requests and
reply. In such a case, the echo request for TTL>n MUST NOT have 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 Downstream Mapping TLVs, until a reply is received with a Downstream
Mapping. Mapping.
5. Reliable Reply Path Normative References
One of the issues that are faced with MPLS ping is to distinguish
between a failure in the forward path (the MPLS path being 'pinged')
and a failure in the return path. Note that this problem exists with
vanilla IP ping as well. In the case of MPLS ping, it is assumed
that the IP control and data planes are reliable. However, it could
be that the forwarding in the return path is via an MPLS LSP.
In this specification, we give two solutions for this problem. One
is to set the Router Alert option in the MPLS echo reply. When a
router sees this option, it MUST forward the packet as an IP packet.
Note that this may not work if some transit LSR does not support MPLS
ping.
Another option is to send the echo reply via the control plane. At
present, this is defined only for RSVP-TE LSPs, and described below.
These options are controlled by the ingress LSR, using the Reply Mode
in the MPLS echo request packet.
5.1. RSVP-TE Extension
To test an LSP's liveliness, an ingress LSR sends MPLS echo requests
over the LSP being tested. When an egress LSR receives the message,
it needs to acknowledge the ingress LSR by sending an LSP_ECHO object
in a RSVP Resv message. The object has the following format:
Class = LSP_ECHO (use form 11bbbbbb for compatibility)
C-Type = 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TimeStamp (seconds) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TimeStamp (microseconds) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| UDP Source Port | Return Code | Return Subcode|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The Sequence Number is copied from the Sequence Number of the echo
request. The TimeStamp is set to the time the echo request is
received. The UDP Source Port is copied from the UDP source port of
the MPLS echo request. The FEC is implied by the Session and the
Sender Template Objects.
5.2. Operation
For the sake of brevity in the context of this document by "the
control plane" we mean "the RSVP-TE component of the control plane".
Consider an LSP between an ingress LSR and an egress LSR spanning
multiple LSR hops.
5.3. Procedures at the ingress LSR
One must ensure before setting the Reply Mode to "reply via the
control plane" that the egress LSR supports this feature.
The ingress LSR, say X, builds an MPLS echo request as in section
"Sending an MPLS Echo Request". The FEC Type must be an RVSP Session
Query. X also sets the Reply Mode to "reply via the control plane".
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-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
LSP_ECHO object and refreshes the Resv message.
5.5. Procedures for the intermediate LSR's
At intermediate LSRs, normal RSVP processing procedures will cause
the LSP_ECHO object to be forwarded as RSVP messages are refreshed.
At the LSR's that support MPLS ping the Resv messages that carry the
LSP_ECHO object MUST be delivered upstream immediately.
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 [KEYWORDS] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[LABEL-STACK] Rosen, E., et al, "MPLS Label Stack Encoding", RFC [LABEL-STACK] Rosen, E., et al, "MPLS Label Stack Encoding", RFC
3032, January 2001. 3032, January 2001.
[RSVP] Braden, R. (Editor), et al, "Resource ReSerVation protocol [RSVP] Braden, R. (Editor), et al, "Resource ReSerVation protocol
(RSVP) -- Version 1 Functional Specification," RFC 2205, (RSVP) -- Version 1 Functional Specification," RFC 2205,
September 1997. September 1997.
[RSVP-REFRESH] Berger, L., et al, "RSVP Refresh Overhead Reduction [RSVP-REFRESH] Berger, L., et al, "RSVP Refresh Overhead Reduction
Extensions", RFC 2961, April 2001. Extensions", RFC 2961, April 2001.
[RSVP-TE] Awduche, D., et al, "RSVP-TE: Extensions to RSVP for LSP [RSVP-TE] Awduche, D., et al, "RSVP-TE: Extensions to RSVP for LSP
tunnels", RFC 3209, December 2001. tunnels", RFC 3209, December 2001.
7. Informative References Informative References
[ICMP] Postel, J., "Internet Control Message Protocol", RFC 792. [ICMP] Postel, J., "Internet Control Message Protocol", RFC 792.
[LDP] Andersson, L., et al, "LDP Specification", RFC 3036, January [LDP] Andersson, L., et al, "LDP Specification", RFC 3036, January
2001. 2001.
8. Security Considerations Security Considerations
There are at least two approaches to attacking LSRs using the There are at least two approaches to attacking LSRs using the
mechanisms defined here. One is a Denial of Service attack, by mechanisms defined here. One is a Denial of Service attack, by
sending MPLS echo requests/replies to LSRs and thereby increasing sending MPLS echo requests/replies to LSRs and thereby increasing
their workload. The other is obfuscating the state of the MPLS data their workload. The other is obfuscating the state of the MPLS data
plane liveness by spoofing, hijacking, replaying or otherwise plane liveness by spoofing, hijacking, replaying or otherwise
tampering with MPLS echo requests and replies. tampering with MPLS echo requests and replies.
Authentication will help reduce the number of seemingly valid MPLS Authentication will help reduce the number of seemingly valid MPLS
echo requests, and thus cut down the Denial of Service attacks; echo requests, and thus cut down the Denial of Service attacks;
skipping to change at page 21, line 14 skipping to change at page 20, line 5
tampering attacks; one hopes to use some mechanism devised or tampering attacks; one hopes to use some mechanism devised or
suggested by the RPSec WG. It is not clear how to prevent hijacking suggested by the RPSec WG. It is not clear how to prevent hijacking
(non-delivery) of echo requests or replies; however, if these (non-delivery) of echo requests or replies; however, if these
messages are indeed hijacked, MPLS ping will report that the data messages are indeed hijacked, MPLS ping will report that the data
plane isn't working as it should. plane isn't working as it should.
It doesn't seem vital (at this point) to secure the data carried in It doesn't seem vital (at this point) to secure the data carried in
MPLS echo requests and replies, although knowledge of the state of MPLS echo requests and replies, although knowledge of the state of
the MPLS data plane may be considered confidential by some. the MPLS data plane may be considered confidential by some.
9. IANA Considerations 5. IANA Considerations
(To be filled in a later revision) The TCP and UDP port number 3503 has been allocated by IANA for LSP
echo requests and replies.
10. Acknowledgments The following sections detail the new name spaces to be managed by
IANA. For each of these name spaces, the space is divided into
assignment ranges; the following terms are used in describing the
procedures by which IANA allocates values: "Standards Action" (as
defined in [IANA]); "Expert Review" and "Vendor Private Use".
Values from "Expert Review" ranges MUST be registered with IANA, and
MUST be accompanied by an Experimental RFC that describes the format
and procedures for using the code point.
Values from "Vendor Private" ranges MUST NOT be registered with IANA;
however, the message MUST contain an enterprise code as registered
with the IANA SMI Network Management Private Enterprise Codes. For
each name space that has a Vendor Private range, it must be specified
where exactly the SMI Enterprise Code resides; see below for
examples. In this way, several enterprises (vendors) can use the
same code point without fear of collision.
5.1. Message Types, Reply Modes, Return Codes
It is requested that IANA maintain registries for Message Types,
Reply Modes, Return Codes and Return Subcodes. Each of these can
take values in the range 0-255. Assignments in the range 0-191 are
via Standards Action; assignments in the range 192-251 are made via
Expert Review; values in the range 252-255 are for Vendor Private
Use, and MUST NOT be allocated.
If any of these fields fall in the Vendor Private range, a top-level
Vendor Enterprise Code TLV MUST be present in the message.
5.2. TLVs
It is requested that IANA maintain registries for the Type field of
top-level TLVs as well as for sub-TLVs. The valid range for each of
these is 0-65535. Assignments in the range 0-32767 are made via
Standards Action; assignments in the range 32768-64511 are made via
Expert Review; values in the range 64512-65535 are for Vendor Private
Use, and MUST NOT be allocated.
If a TLV or sub-TLV has a Type that falls in the range for Vendor
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, This document is the outcome of many discussions among many people,
that include Manoj Leelanivas, Paul Traina, Yakov Rekhter, Der-Hwa that include Manoj Leelanivas, Paul Traina, Yakov Rekhter, Der-Hwa
Gan, Brook Bailey, Eric Rosen and Ina Minei. Gan, Brook Bailey, Eric Rosen and Ina Minei.
The Multipath Exercise sub-field of the Downstream Mapping TLV was The Multipath Exercise sub-field of the Downstream Mapping TLV was
adapted from text suggested by Curtis Villamizar. adapted from text suggested by Curtis Villamizar.
11. Appendix Appendix
This appendix specifies non-normative aspects of detecting MPLS data This appendix specifies non-normative aspects of detecting MPLS data
plane liveness. plane liveness.
11.1. CR-LDP FEC 5.1. CR-LDP FEC
This section describes how a CR-LDP FEC can be included in an Echo This section describes how a CR-LDP FEC can be included in an Echo
Request using the following FEC subtype: Request using the following FEC subtype:
Sub-Type # Length Value Field Sub-Type # Length Value Field
---------- ------ ----------- ---------- ------ -----------
5 6 CR-LDP LSP ID 5 6 CR-LDP LSP ID
The value consists of the LSPID of the LSP being pinged. An LSPID is The value consists of the LSPID of the LSP being pinged. An LSPID is
a four octet IPv4 address (a local address on the ingress LSR, for a four octet IPv4 address (a local address on the ingress LSR, for
skipping to change at page 22, line 9 skipping to change at page 21, line 41
per LSP on a given ingress LSR. per LSP on a given ingress LSR.
0 1 2 3 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 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Ingress LSR Router ID | | Ingress LSR Router ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Must Be Zero | LSP ID | | Must Be Zero | LSP ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
11.2. Downstream Mapping for CR-LDP 5.2. Downstream Mapping for CR-LDP
If a label in a Downstream Mapping was learned via CR-LDP, the If a label in a Downstream Mapping was learned via CR-LDP, the
Protocol field in the Mapping TLV can use the following entry: Protocol field in the Mapping TLV can use the following entry:
Protocol # Signaling Protocol Protocol # Signaling Protocol
---------- ------------------ ---------- ------------------
5 CR-LDP 5 CR-LDP
12. Authors' Addresses Authors' Addresses
Kireeti Kompella Kireeti Kompella
Nischal Sheth Nischal Sheth
Juniper Networks Juniper Networks
1194 N.Mathilda Ave 1194 N.Mathilda Ave
Sunnyvale, CA 94089 Sunnyvale, CA 94089
e-mail: kireeti@juniper.net e-mail: kireeti@juniper.net
e-mail: nsheth@juniper.net e-mail: nsheth@juniper.net
Ping Pan Ping Pan
skipping to change at page 23, line 16 skipping to change at page 23, line 5
email: swadhwa@unispherenetworks.com email: swadhwa@unispherenetworks.com
phone: +1 978.589.0697 phone: +1 978.589.0697
Ronald P. Bonica Ronald P. Bonica
WorldCom WorldCom
22001 Loudoun County Pkwy 22001 Loudoun County Pkwy
Ashburn, Virginia, 20147 Ashburn, Virginia, 20147
email: ronald.p.bonica@wcom.com email: ronald.p.bonica@wcom.com
phone: +1 703.886.1681 phone: +1 703.886.1681
13. Intellectual Property Rights Notices Intellectual Property Rights Notices
The IETF takes no position regarding the validity or scope of any The IETF takes no position regarding the validity or scope of any
intellectual property or other rights that might be claimed to intellectual property or other rights that might be claimed to
pertain to the implementation or use of the technology described in pertain to the implementation or use of the technology described in
this document or the extent to which any license under such rights this document or the extent to which any license under such rights
might or might not be available; neither does it represent that it might or might not be available; neither does it represent that it
has made any effort to identify any such rights. Information on the has made any effort to identify any such rights. Information on the
IETF's procedures with respect to rights in standards-track and IETF's procedures with respect to rights in standards-track and
standards-related documentation can be found in BCP-11. Copies of standards-related documentation can be found in BCP-11. Copies of
claims of rights made available for publication and any assurances of claims of rights made available for publication and any assurances of
 End of changes. 

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