draft-ietf-mpls-p2mp-lsp-ping-03.txt   draft-ietf-mpls-p2mp-lsp-ping-04.txt 
Network Working Group Seisho Yasukawa (Editor) Network Working Group Seisho Yasukawa (Editor)
Internet-Draft NTT Internet-Draft NTT
Intended Status: Standards Track Adrian Farrel (Editor) Intended Status: Standards Track Adrian Farrel (Editor)
Expires: September 2007 Old Dog Consulting Expires: September 2007 Old Dog Consulting
Detecting Data Plane Failures in Point-to-Multipoint Multiprotocol Detecting Data Plane Failures in Point-to-Multipoint Multiprotocol
Label Switching (MPLS) - Extensions to LSP Ping Label Switching (MPLS) - Extensions to LSP Ping
draft-ietf-mpls-p2mp-lsp-ping-03.txt draft-ietf-mpls-p2mp-lsp-ping-04.txt
Status of this Memo Status of this Memo
By submitting this Internet-Draft, each author represents that any By submitting this Internet-Draft, each author represents that any
applicable patent or other IPR claims of which he or she is aware applicable patent or other IPR claims of which he or she is aware
have been or will be disclosed, and any of which he or she becomes have been or will be disclosed, and any of which he or she becomes
aware will be disclosed, in accordance with Section 6 of BCP 79. aware will be disclosed, in accordance with Section 6 of BCP 79.
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
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0.3 Changes from 02 to 03 0.3 Changes from 02 to 03
- Update references. - Update references.
- Update boilerplate. - Update boilerplate.
- Fix typos. - Fix typos.
- Clarify in 3.2.2 that a recipient of an echo request must reply - Clarify in 3.2.2 that a recipient of an echo request must reply
only onced it has applied incoming rate limiting. only once it has applied incoming rate limiting.
- Tidy references to bootstrapping for [MCAST-CV] in 1.1. - Tidy references to bootstrapping for [MCAST-CV] in 1.1.
- Allow multiple sub-TLVs in the P2MP Egress Identifier TLV in - Allow multiple sub-TLVs in the P2MP Egress Identifier TLV in
sections 3.2.1, 3.2.2, 3.2.4, 3.3.1, and 3.3.4. sections 3.2.1, 3.2.2, 3.2.4, 3.3.1, and 3.3.4.
- Clarify how to handle a P2MP Egress Identifier TLV with no sub-TLVs - Clarify how to handle a P2MP Egress Identifier TLV with no sub-TLVs
in sections 3.2.1 and 3.2.2. in sections 3.2.1 and 3.2.2.
0.4 Changes from 03 to 04
- Revert to previous text in sections 3.2.1, 3.2.2, 3.2.4, 3.3.1, and
3.3.4 with respect to multiple sub-TLVs in the P2MP Egress
Identifier TLV.
1. Introduction 1. Introduction
Simple and efficient mechanisms that can be used to detect data plane Simple and efficient mechanisms that can be used to detect data plane
failures in point-to-point (P2P) MPLS LSP are described in failures in point-to-point (P2P) MPLS LSP are described in
[RFC4379]. The techniques involve information carried in an MPLS [RFC4379]. The techniques involve information carried in an MPLS
"echo request" and "echo reply", and mechanisms for transporting the "echo request" and "echo reply", and mechanisms for transporting the
echo reply. The echo request and reply messages provide sufficient echo reply. The echo request and reply messages provide sufficient
information to check correct operation of the data plane, as well as information to check correct operation of the data plane, as well as
a mechanism to verify the data plane against the control plane, and a mechanism to verify the data plane against the control plane, and
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As described in Section 2.2, it may be desirable to restrict the As described in Section 2.2, it may be desirable to restrict the
operation of LSP Ping to a single egress. Since echo requests are operation of LSP Ping to a single egress. Since echo requests are
forwarded through the data plane without interception by the control forwarded through the data plane without interception by the control
plane (compare with traceroute mode), there is no facility to limit plane (compare with traceroute mode), there is no facility to limit
the propagation of echo requests, and they will automatically be the propagation of echo requests, and they will automatically be
forwarded to all (reachable) egresses. forwarded to all (reachable) egresses.
However, the intended egress under test can be identified by the However, the intended egress under test can be identified by the
inclusion of a P2MP Egress Identifier TLV containing an IPv4 P2MP inclusion of a P2MP Egress Identifier TLV containing an IPv4 P2MP
Egress Identifier sub-TLV or an IPv6 P2MP Egress Identifier sub-TLV. Egress Identifier sub-TLV or an IPv6 P2MP Egress Identifier sub-TLV.
The P2MP Egress Identifier TLV MUST contain at least one sub-TLV and The P2MP Egress Identifier TLV SHOULD contain precisely one sub-TLV.
MAY contain more than one sub-TLV. If the P2MP Egress Identifier TLV If the TLV contains no sub-TLVs it SHOULD be processed as if the
contains no sub-TLVs the echo request MUST be processed as if the TLV whole TLV were absent (causing all egresses to respond as described
were absent (causing all egresses to respond as described below). below). If the TLV contains more than one sub-TLV, the first MUST be
precessed as described in this document, and subsequent sub-TLVs
If the P2MP Egress Identifier TLV contains more than one sub-TLV, SHOULD be ignored.
each MUST be processed in turn as described in this document. An
initiator sending a P2MP echo request MUST be aware that processing
a very large number of sub-TLVs within a P2MP Egress Identifier TLV
may represent a burden to an egress LSR, so the number of sub-TLVs
SHOULD be limited to a 'reasonable' number. An upper threshold of
50 sub-TLVs is RECOMMENDED.
An initiator may indicate that it wishes all egresses to respond to An initiator may indicate that it wishes all egresses to respond to
an echo request by omitting the P2MP Egress Identifier TLV. an echo request by omitting the P2MP Egress Identifier TLV.
Note that the ingress of a multicast LDP LSP will not know the Note that the ingress of a multicast LDP LSP will not know the
identities of the egresses of the LSP except by some external means identities of the egresses of the LSP except by some external means
such as running P2MP LSP Ping to all egresses. such as running P2MP LSP Ping to all egresses.
3.2.2. Ping Mode Egress Procedures 3.2.2. Ping Mode Egress Procedures
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Session sub-TLV, an RSVP P2MP IPv6 Session sub-TLV, or a Multicast Session sub-TLV, an RSVP P2MP IPv6 Session sub-TLV, or a Multicast
LDP FEC Stack Sub-TLV MUST determine whether it is an intended egress LDP FEC Stack Sub-TLV MUST determine whether it is an intended egress
of the P2MP LSP in question by checking with the control plane. If it of the P2MP LSP in question by checking with the control plane. If it
is not supposed to be an egress, it MUST respond according to the is not supposed to be an egress, it MUST respond according to the
setting of the Response Type field in the echo message following the setting of the Response Type field in the echo message following the
rules defined in [RFC4379]. rules defined in [RFC4379].
If the egress LSR that receives an echo request and allows it through If the egress LSR that receives an echo request and allows it through
its rate limiting is an intended egress of the P2MP LSP, the LSR MUST its rate limiting is an intended egress of the P2MP LSP, the LSR MUST
check to see whether it is an intended Ping recipient. If a P2MP check to see whether it is an intended Ping recipient. If a P2MP
Egress Identifier TLV is present and contains an address in any of Egress Identifier TLV is present and contains an address that
its sub-TLVs that indicates any address that is local to the LSR, the indicates any address that is local to the LSR, the LSR MUST respond
LSR MUST respond according to the setting of the Response Type field according to the setting of the Response Type field in the echo
in the echo message following the rules defined in [RFC4379]. If the message following the rules defined in [RFC4379]. If the P2MP Egress
P2MP Egress Identifier TLV is present, but does none of its sub-TLVs Identifier TLV is present, but does not identify the egress LSR, it
identifies the egress LSR, it MUST NOT respond to the echo request. MUST NOT respond to the echo request. If the P2MP Egress Identifier
If the P2MP Egress Identifier TLV is not present (or, in the error TLV is not present (or, in the error case, is present but does not
case, is present but contains no sub-TLVs), but the egress LSR that a sub-TLVs), but the egress LSR that received the echo request is an
received the echo request is an intended egress of the LSP, the LSR intended egress of the LSP, the LSR MUST respond according to the
MUST respond according to the setting of the Response Type field in setting of the Response Type field in the echo message following the
the echo message following the rules defined in [RFC4379]. rules defined in [RFC4379].
3.2.3. Jittered Responses 3.2.3. Jittered Responses
The initiator (ingress) of a ping request MAY request the responding The initiator (ingress) of a ping request MAY request the responding
egress to introduce a random delay (or jitter) before sending the egress to introduce a random delay (or jitter) before sending the
response. The randomness of the delay allows the responses from response. The randomness of the delay allows the responses from
multiple egresses to be spread over a time period. Thus this multiple egresses to be spread over a time period. Thus this
technique is particularly relevant when the entire LSP tree is being technique is particularly relevant when the entire LSP tree is being
pinged since it helps prevent the ingress (or nearby routers) from pinged since it helps prevent the ingress (or nearby routers) from
being swamped by responses, or from discarding responses due to rate being swamped by responses, or from discarding responses due to rate
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|Type = TBD (P2MP Egress ID TLV)| Length = Variable | |Type = TBD (P2MP Egress ID TLV)| Length = Variable |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ Sub-TLVs ~ ~ Sub-TLVs ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Sub-TLVs: Sub-TLVs:
Zero, one or more sub-TLVs as defined below. Zero, one or more sub-TLVs as defined below.
If no sub-TLVs are present, the TLV MUST be processed as if it If no sub-TLVs are present, the TLV MUST be processed as if it
were absent. If more than one sub-TLV is present each MUST be were absent. If more than one sub-TLV is present the first MUST
processed as described. be processed as described in this document, and subsequent
sub-TLVs SHOULD be ignored.
The P2MP Egress Identifier TLV only has meaning on an echo request The P2MP Egress Identifier TLV only has meaning on an echo request
message. If present on an echo response message, it SHOULD be message. If present on an echo response message, it SHOULD be
ignored. ignored.
Two Sub-TLVs are defined for inclusion in the P2MP Egress Identifier Two Sub-TLVs are defined for inclusion in the P2MP Egress Identifier
TLV carried on the echo request message. These are: TLV carried on the echo request message. These are:
Sub-Type # Length Value Field Sub-Type # Length Value Field
---------- ------ ----------- ---------- ------ -----------
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When the TTL for the MPLS packet carrying an echo request expires the When the TTL for the MPLS packet carrying an echo request expires the
packet MUST be passed to the control plane as specified in [RFC4379]. packet MUST be passed to the control plane as specified in [RFC4379].
If the LSP under test is a multicast LDP LSP and if the echo request If the LSP under test is a multicast LDP LSP and if the echo request
carries a P2MP Egress Identifier TLV the LSR MUST treat the echo carries a P2MP Egress Identifier TLV the LSR MUST treat the echo
request as malformed and MUST process it according to the rules request as malformed and MUST process it according to the rules
specified in [RFC4379]. specified in [RFC4379].
Otherwise, the LSR MUST NOT return an echo response unless the Otherwise, the LSR MUST NOT return an echo response unless the
responding LSR lies on the path of the P2MP LSP to any of the responding LSR lies on the path of the P2MP LSP to the egress
egresses identified by the P2MP Egress Identifier TLV carried on the identified by the P2MP Egress Identifier TLV carried on the request,
request, or if no such Sub-TLV is present. or if no such Sub-TLV is present.
If sent, the echo response MUST identifiy the next hop of the path of If sent, the echo response MUST identifiy the next hop of the path of
the LSP in the data plane by including a Downstream Mapping TLV as the LSP in the data plane by including a Downstream Mapping TLV as
described in [RFC4379]. described in [RFC4379].
3.3.1.1. Correlating Traceroute Responses 3.3.1.1. Correlating Traceroute Responses
When traceroute is being simultaneously applied to multiple egresses, When traceroute is being simultaneously applied to multiple egresses,
it is important that the ingress should be able to correlate the echo it is important that the ingress should be able to correlate the echo
responses with the branches in the P2MP tree. Without this responses with the branches in the P2MP tree. Without this
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LSRs that must not reply to the request because, although they lie LSRs that must not reply to the request because, although they lie
on the P2MP tree, they do not lie on the path to the egress that is on the P2MP tree, they do not lie on the path to the egress that is
being traced. being traced.
Thus, an LSR on a P2MP MPLS LSP MUST NOT respond to an echo request Thus, an LSR on a P2MP MPLS LSP MUST NOT respond to an echo request
when the TTL has expired if any of the following applies: when the TTL has expired if any of the following applies:
- The Reply Type indicates that no reply is required - The Reply Type indicates that no reply is required
- There is a P2MP Egress Identifier TLV present on the echo request - There is a P2MP Egress Identifier TLV present on the echo request
(which means that the LSP is a P2MP MPLS TE LSP), but none of the (which means that the LSP is a P2MP MPLS TE LSP), but the address
addresses identifies an egress that is reached through this LSR for does not identify an egress that is reached through this LSR for
this particular P2MP MPLS LSP. this particular P2MP MPLS LSP.
3.3.5. Modifications to the Downstream Mapping TLV 3.3.5. Modifications to the Downstream Mapping TLV
A new B-flag is added to the Downstream Mapping TLV to indicate that A new B-flag is added to the Downstream Mapping TLV to indicate that
the reporting LSR is not a branch for this LSP (cleared to zero) or the reporting LSR is not a branch for this LSP (cleared to zero) or
is a branch (set to one). is a branch (set to one).
A new E-flag is added to the Downstream Mapping TLV to indicate that A new E-flag is added to the Downstream Mapping TLV to indicate that
the reporting LSR is not a bud node for this LSP (cleared to zero) or the reporting LSR is not a bud node for this LSP (cleared to zero) or
 End of changes. 8 change blocks. 
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