< draft-ietf-mpls-mldp-node-protection-05.txt   draft-ietf-mpls-mldp-node-protection-06.txt >
Network Working Group IJ. Wijnands, Ed. Network Working Group IJ. Wijnands, Ed.
Internet-Draft K. Raza Internet-Draft K. Raza
Intended status: Standards Track Cisco Systems, Inc. Intended status: Standards Track Cisco Systems, Inc.
Expires: August 13, 2015 E. Rosen Expires: March 18, 2016 A. Atlas
A. Atlas
Juniper Networks, Inc. Juniper Networks, Inc.
J. Tantsura J. Tantsura
Ericsson Ericsson
Q. Zhao Q. Zhao
Huawei Technology Huawei Technology
February 9, 2015 September 15, 2015
mLDP Node Protection mLDP Node Protection
draft-ietf-mpls-mldp-node-protection-05 draft-ietf-mpls-mldp-node-protection-06
Abstract Abstract
This document describes procedures to support node protection for This document describes procedures to support node protection for
Point-to-Multipoint and Multipoint-to-Multipoint Label Switched Paths Point-to-Multipoint and Multipoint-to-Multipoint Label Switched Paths
(MP LSPs) that has been built by "Multipoint Label Distribution (MP LSPs) that have been built by the "Multipoint Label Distribution
Protocol"(mLDP). In order to protect a node N, the Point of Local Protocol"(mLDP) [RFC6388]. In order to protect a node N, the Point
Repair (PLR) LSR of N must learn the Merge Point (MPT) LSR(s) of node of Local Repair (PLR) Label Switched Router (LSR) of N must learn the
N such that traffic can be redirected to them in case node N fails. Merge Point (MPT) LSR(s) of node N such that traffic can be
Redirecting the traffic around the failed node N depends on existing redirected to them in case node N fails. Redirecting the traffic
P2P LSPs. The pre-established LSPs originate from the PLR LSR and around the failed node N depends on existing P2P LSPs. The pre-
terminate on the MPT LSRs while bypassing LSR N. established LSPs originate from the PLR LSR and terminate on the MPT
LSRs while bypassing LSR N.
Status of this Memo Status of this Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on August 13, 2015. This Internet-Draft will expire on March 18, 2016.
Copyright Notice Copyright Notice
Copyright (c) 2015 IETF Trust and the persons identified as the Copyright (c) 2015 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
skipping to change at page 2, line 24 skipping to change at page 2, line 24
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Conventions used in this document . . . . . . . . . . . . 3 1.1. Conventions used in this document . . . . . . . . . . . . 3
1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3 1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
2. PLR Determination . . . . . . . . . . . . . . . . . . . . . . 4 2. PLR Determination . . . . . . . . . . . . . . . . . . . . . . 4
2.1. Transit node procedure . . . . . . . . . . . . . . . . . . 4 2.1. Transit node procedure . . . . . . . . . . . . . . . . . . 4
2.2. MP2MP root node procedure . . . . . . . . . . . . . . . . 5 2.2. MP2MP root node procedure . . . . . . . . . . . . . . . . 5
2.3. PLR information encoding . . . . . . . . . . . . . . . . . 5 2.3. PLR information encoding . . . . . . . . . . . . . . . . . 6
3. Using the tLDP session . . . . . . . . . . . . . . . . . . . . 7 3. Using the tLDP session . . . . . . . . . . . . . . . . . . . . 8
4. Link or node failure . . . . . . . . . . . . . . . . . . . . . 9 4. Link or node failure . . . . . . . . . . . . . . . . . . . . . 10
4.1. Re-convergence after node/link failure . . . . . . . . . . 10 4.1. Re-convergence after node/link failure . . . . . . . . . . 11
4.1.1. Node failure . . . . . . . . . . . . . . . . . . . . . 10 4.1.1. Node failure . . . . . . . . . . . . . . . . . . . . . 11
4.1.2. Link failure . . . . . . . . . . . . . . . . . . . . . 11 4.1.2. Link failure . . . . . . . . . . . . . . . . . . . . . 12
4.1.3. Switching to new primary path . . . . . . . . . . . . 11 4.1.3. Switching to new primary path . . . . . . . . . . . . 12
5. mLDP Capabilities for Node Protection . . . . . . . . . . . . 11 5. mLDP Capabilities for Node Protection . . . . . . . . . . . . 12
5.1. PLR capability . . . . . . . . . . . . . . . . . . . . . . 12 5.1. PLR capability . . . . . . . . . . . . . . . . . . . . . . 13
5.2. MPT capability . . . . . . . . . . . . . . . . . . . . . . 12 5.2. MPT capability . . . . . . . . . . . . . . . . . . . . . . 13
5.3. The Protected LSR . . . . . . . . . . . . . . . . . . . . 12 5.3. The Protected LSR . . . . . . . . . . . . . . . . . . . . 13
5.4. The Node Protection Capability . . . . . . . . . . . . . . 13 5.4. The Node Protection Capability . . . . . . . . . . . . . . 14
6. Security Considerations . . . . . . . . . . . . . . . . . . . 14 6. Security Considerations . . . . . . . . . . . . . . . . . . . 15
7. IANA considerations . . . . . . . . . . . . . . . . . . . . . 14 7. IANA considerations . . . . . . . . . . . . . . . . . . . . . 15
8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 14 8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 15
9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 15 9. Contributor Addresses . . . . . . . . . . . . . . . . . . . . 16
9.1. Normative References . . . . . . . . . . . . . . . . . . . 15 10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 16
9.2. Informative References . . . . . . . . . . . . . . . . . . 15 10.1. Normative References . . . . . . . . . . . . . . . . . . . 16
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 15 10.2. Informative References . . . . . . . . . . . . . . . . . . 16
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 17
1. Introduction 1. Introduction
This document describes procedures to support node protection for This document describes procedures to support node protection for
Point-to-Multipoint and Multipoint-to-Multipoint Label Switched Paths Point-to-Multipoint and Multipoint-to-Multipoint Label Switched Paths
(MP LSPs) that has been built by "Multipoint Label Distribution (MP LSPs) that have been built by the "Multipoint Label Distribution
Protocol"(mLDP). In order to protect a node N, the Point of Local Protocol"(mLDP) [RFC6388]. In order to protect a node N, the Point
Repair (PLR) LSR of N must learn the Merge Point (MPT) LSR(s) of node of Local Repair (PLR) LSR of N must learn the Merge Point (MPT)
N such that traffic can be redirected to them in case node N fails. LSR(s) of node N such that traffic can be redirected to them in case
Redirecting the traffic around the failed node N depends on existing node N fails. Redirecting the traffic around the failed node N
P2P LSPs. The pre-established LSPs originate from the PLR LSR and depends on existing P2P LSPs. The pre-established LSPs originate
terminate on the MPT LSRs while bypassing LSR N. The procedures to from the PLR LSR and terminate on the MPT LSRs while bypassing LSR N.
setup these P2P LSPs are outside the scope of this document, but one The procedures to setup these P2P LSPs are outside the scope of this
can imagine using RSVP-TE or LDP LFA based techniques to accomplish document, but one can imagine using Resource Reservation Protocol for
this. Traffic Engineering (RSVP-TE) [RFC5420] or Label Distribution
Protocol (LDP) Loop Free Alternative (LFA) [RFC5286] based techniques
to accomplish this.
The solution described in this document notifies the PLR(s) of the The solution described in this document notifies the PLR(s) of the
MPT LST(s) via signalling using a Targetted LDP (tLDP) session MPT LST(s) via signalling using a Targeted LDP (tLDP) session
[RFC5036]. By having a tLDP session with the PLR, most of the (m)LDP [RFC7060]. By having a tLDP session with the PLR, no additional
features currently defined should just work, like Make-Before-Break procedures need to be defined in order to support Make-Before-Break
(MBB), Graceful Restart (GR), Typed Wildcard FEC support, etc. All (MBB), Graceful Restart (GR) and Typed Wildcard FEC support. All
this is achieved at the expense of having additional tLDP sessions this is achieved at the expense of having additional tLDP sessions
between each MPT and PLR LSR. between each MPT and PLR LSR.
In order for a node to be protected, the protecterd node, the PLR and
the MPT MUST support the procedures as described in this draft.
Detecting the protected node, PLR and MPT support these procedures is
done using [RFC5561].
1.1. Conventions used in this document 1.1. Conventions used in this document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119]. document are to be interpreted as described in RFC 2119 [RFC2119].
The terms "node" is used to refer to an LSR and used interchangeably. The terms "node" is used to refer to an LSR and used interchangeably.
The terms "PLR" and "MPT" are used as shorthand to refer to "PLR LSR" The terms "PLR" and "MPT" are used as shorthand to refer to "PLR LSR"
and "MPT LSR" respectively. and "MPT LSR" respectively.
skipping to change at page 4, line 7 skipping to change at page 4, line 13
one or more Merge Point LSRs). one or more Merge Point LSRs).
MPT: Merge Point (the LSR that merges the backup LSP with primary MPT: Merge Point (the LSR that merges the backup LSP with primary
LSP. Note, there can be multiple MPT LSRs for a single MP-LSP LSP. Note, there can be multiple MPT LSRs for a single MP-LSP
node protection). node protection).
tLDP: Targeted LDP. tLDP: Targeted LDP.
MP LSP: Multi-Point LSP (either a P2MP or MP2MP LSP). MP LSP: Multi-Point LSP (either a P2MP or MP2MP LSP).
root node: The root of either a P2MP or MP2MP LSP as defined in
[RFC6388].
2. PLR Determination 2. PLR Determination
In order for a MPT to establish a tLDP session with a PLR, it first In order for a MPT to establish a tLDP session with a PLR, it first
has to learn the PLR for a particular MP LSP. It is the has to learn the PLR for a particular MP LSP. It is the
responsibility of the protected node N to advertise the address of responsibility of the protected node N to advertise the address of
the PLR to the MPT. The PLR address for a MP LSP on node N is the the PLR to the MPT. The PLR address for a MP LSP on node N is the
address of the upstream LDP peer, but only when node N is NOT the address of the upstream LDP peer, but only when node N is NOT the
root node of the MP2MP LSP. If the upstream LDP peer is unable to root node of the MP2MP LSP. If the upstream LDP peer is unable to
function as PLR, the procedures in this document do not apply and are function as PLR, the procedures in this document do not apply and are
out of the scope. If node N is the root node, the procedures are out of the scope. If node N is the root node, the procedures are
slightly different as described in Section 2.2. The procedures that slightly different as described in Section 2.2. The procedures that
follow assume that all the participating nodes (N, PLRs, MPTs) are follow assume that all the participating nodes (N, PLRs, MPTs) are
enabled (e.g. by a user configuration) to support and implement the enabled (e.g., by a user configuration) to support and implement the
PLR determination feature. PLR determination feature.
The procedures as documented in this draft requires the protected
node to be directly connected to the PLR and MPT nodes. This because
mLDP depends on unicast routing to determine the upstream LSR and
unicast routing (by default) only has information about the next-hop
and not beyond that. Support for non-directly connected PLR and MPT
nodes is outside the scope of this document.
2.1. Transit node procedure 2.1. Transit node procedure
Below we are describing the procedures when the protected node is a Find below the procedures for when the protected node is a transit
transit node along the path to the root. node along the path to the root.
root root
^ ^
| |
(LSR1) (LSR1)
. | . . | .
. | . . | .
. (N) . . (N) .
. / \ . . / \ .
. / \. . / \.
(LSR2) (LSR3) (LSR2) (LSR3)
| | | |
Figure 1. Figure 1.
N: The node being protected, N: The node being protected,
...: Backup LSPs from LSR1 to the LSR2 and LSR3. ...: Backup LSPs from LSR1 to LSR2 and LSR3.
Node N uses the root address of the MP LSP to determine the upstream Node N uses the root address of the MP LSP to determine the upstream
LSR for a given MP LSP following the procedures as documented in LSR for a given MP LSP following the procedures as documented in
[RFC6388] section 2.4.1.1. The upstream LSR in figure 1 is LSR1 [RFC6388] section 2.4.1.1. The upstream LSR in figure 1 is LSR1
because it is the first hop along the shortest path to reach the root because it is the first hop along the shortest path to reach the root
address. After determining the upstream LSR, node N (which is address. After determining the upstream LSR, node N (which has the
feature enabled), MUST advertise the address of LSR1 as the PLR node protection feature enabled), MUST advertise the address of LSR1
address to the downstream members of the MP LSP (i.e. LSR2 and LSR3) as the PLR address to the downstream members of the MP LSP (i.e.,
if the given downstream member has announced support for node LSR2 and LSR3) if the given downstream member has announced support
protection (see Section 5) for Capability negotiation). For the for node protection (see Section 5) during Capability negotiation).
format and encoding of PLR address information, see Section 2.3. For the format and encoding of PLR address information, see
Section 2.3.
2.2. MP2MP root node procedure Note, in order for the protected traffic to reach nodes LSR2 and
LSR3, LSR1 MUST have two unidirectinal LSPs to LSR2 and LSR3,
bypassing node N. Procedures how to setup these LSPs are outside the
scope of this documemnt.
In this section we are describing the procedures for when the 2.2. MP2MP root node procedure
protected node is the root of a MP2MP LSP. Consider figure 2 below;
Find below the procedures for when the protected node is the root of
a MP2MP LSP. Consider figure 2 below;
| |
(LSR1) (LSR1)
. | . . | .
. | . . | .
. (N) . root . (N) . root
. / \ . . / \ .
. / \. . / \.
(LSR2)....(LSR3) (LSR2)....(LSR3)
| | | |
Figure 2. Figure 2.
skipping to change at page 5, line 41 skipping to change at page 6, line 33
and MPT LSR. An LSR will act as MPT for traffic coming from the and MPT LSR. An LSR will act as MPT for traffic coming from the
other LSR(s) and it will act as PLR for traffic it is sending to the other LSR(s) and it will act as PLR for traffic it is sending to the
other LSR(s). Since node N knows the members of the MP2MP LSP, it other LSR(s). Since node N knows the members of the MP2MP LSP, it
will advertise the member list to its directly connected members, will advertise the member list to its directly connected members,
excluding the member it is sending to. For example, node N will excluding the member it is sending to. For example, node N will
advertise {LSR3,LSR1} list to LSR2 excluding LSR2 from it. Instead advertise {LSR3,LSR1} list to LSR2 excluding LSR2 from it. Instead
of advertising a single PLR when node N is not the root, a list of of advertising a single PLR when node N is not the root, a list of
PLRs is advertised using the procedures documented in Section 2.3. PLRs is advertised using the procedures documented in Section 2.3.
It should be noted that the MP2MP root node protection mechanism It should be noted that the MP2MP root node protection mechanism
don't replace the Root Node Redundancy (RNR) procedures as described doesn't replace the Root Node Redundancy (RNR) procedures as
in [RFC6388] section 7. The node protection procedures in this draft described in [RFC6388] section 7. The node protection procedures in
will help restoring traffic for the existing MP2MP LSPs after node this draft will help in restoring traffic for the existing MP2MP LSPs
failure, but a new root node has to be elected eventually in order to after node failure, but a new root node has to be elected eventually
allow new MP2MP LSPs to be created. in order to allow new MP2MP LSPs to be created.
Note, in order for the protected traffic to be exchanged between
nodes LSR1, LSR2 and LSR3, bidirectional LSPs have to exist between
the LSRs, bypassing node N. Procedures how to setup these LSPs are
outside the scope of this documemnt.
2.3. PLR information encoding 2.3. PLR information encoding
The upstream LSR address is conveyed via an LDP Notification message The upstream LSR address is conveyed via an LDP Notification message
with MP Status TLV, where the MP status TLV contains a new "PLR with an MP Status TLV, where the MP status TLV contains a new "PLR
Status Value Element" that specifies the address of the PLR. Status Value Element" that specifies the address of the PLR.
The new "PLR Status Value Element" is encoded as follows; The new "PLR Status Value Element" is encoded as follows;
PLR Status Element: PLR Status Element:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type = TBA-1 | Length | Addr Family | | Type = TBA-1 | Length | Addr Family |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Addr Fam cont | Num PLR entry | | | Addr Fam cont | Num PLR entry | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
| | | |
| PLR entry (1 or more) ~ | PLR entry (1 or more) ~
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Where Where
Type: PLR Status Value Element (Type TBA-1 to be assigned by IANA) Type: PLR Status Value Element (Type TBA-1 to be assigned by IANA)
Length: The Length field encodes the length of the Status Value Length: The Length field is an unsigned integer that encodes the
following the Length field. The encoded Length varies based on length of the Status Value following the Length field. The
the Address Family and the number of PLR entries. encoded Length varies based on the Addr Family and the number of
PLR entries.
Address Family: Two octet quantity containing a value from IANA's Addr Family: Two octet quantity containing a value from IANA's
"Address Family Numbers" registry that encodes the address family [AFI] registry that encodes the address family for the PLR Address
for the PLR Address encoded in the PLR entry. encoded in the PLR entry.
Num PLR entry: Number of "PLR entries" encoded in the Status Value Num PLR entry: Element as an unsigned, non-zero integer followed
Element, followed by "Num PLR entry" field (please see format of a by that number of "PLR entry" fields in the format specified
PLR entry below). below.
The format of a "PLR Entry" is as follows: The format of a "PLR Entry" is 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|A| Reserved | PLR address | |A| Reserved | PLR address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ PLR address (cont) ~ ~ PLR address (cont) ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Where Where
A bit: 0 = Withdraw, 1 = Add. A bit: 0 = Withdraw, 1 = Add.
Reserved: 15 bits, must be zero on transmit and ignored on receipt Reserved: 15 bits, MUST be zero on transmit and ignored on receipt
PLR address: PLR Address encoded according to Address Family field PLR address: PLR Address encoded according to Address Family field
encoded in the PLR Status Value Element. Note, the length of the encoded in the PLR Status Value Element. Note, the length of the
PLR address field is specific to the Address Family that is PLR address field is specific to the Address Family that is
encoded. encoded.
The size of a "PLR Entry" is the 2 octets ("A bit + Reserved") + PLR The size of a "PLR Entry" is the 2 octets ("A bit + Reserved") + PLR
address length. The length of the PLR address is depending on the address length. The length of the PLR address is dependent on the
Address Family as encoded in the PLR Status Value Element. The size Address Family as encoded in the PLR Status Value Element. The size
of a "PLR entry" is 6 octets and 18 octets respectively for an IPv4 of a "PLR entry" is 6 octets and 18 octets respectively for an IPv4
PLR address and an IPv6 PLR address. PLR address and an IPv6 PLR address.
If the PLR address on N changes for a given MP LSP, N needs to If the PLR address on N changes for a given MP LSP, N needs to
trigger a new PLR Status to update the MPT(s). A node N can trigger a new PLR Status to update the MPT(s). A node N can
advertise or withdraw a given PLR from its PLR set by setting "A bit" advertise or withdraw a given PLR from its PLR set by setting the "A
to 1 or 0 respectively in corresponding PLR entry. Removing a PLR bit" to 1 or 0 respectively in the corresponding PLR entry. Removing
address is likely due to a link failure, see the procedures as a PLR address is likely due to a link failure, see the procedures as
documented in Section 4.1. To remove all PLR addresses belonging to documented in Section 4.1. To remove all PLR addresses belonging to
the encoded Address Family, an LSR N MUST encode PLR Status Value the encoded Address Family, an LSR N MUST encode PLR Status Value
Element with no PLR entry and "Num PLR entry" field MUST be set to Element with no PLR entry and "Num PLR entry" field MUST be set to
zero. zero.
Along with the PLR MP Status a MP FEC TLV MUST be included in the LDP Along with the PLR Status a MP FEC TLV [RFC5036] MUST be included in
Notification message so that a receiver is able to associate the PLR the LDP Notification message so that a receiver is able to associate
Status with the MP LSP. the PLR Status with the MP LSP.
3. Using the tLDP session 3. Using the tLDP session
The receipt of a PLR MP Status (with PLR addresses) for a MP LSP on a The receipt of a PLR MP Status (with PLR addresses) for a MP LSP on a
receiving LSR makes it an MPT for node protection. If not already receiving LSR makes it an MPT for node protection. If not already
established, the MPT LSR MUST establish a tLDP session with all of established, the MPT LSR MUST establish a tLDP session with all of
the learned PLR addresses using the procedures as documented in the learned PLR addresses using the procedures as documented in
[RFC7060]. [RFC7060].
Using Figure 1 as the reference topology, let us assume that both Using Figure 1 as the reference topology, let us assume that both
skipping to change at page 8, line 29 skipping to change at page 9, line 27
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type = TBA-2 | Length | Addr Family | | Type = TBA-2 | Length | Addr Family |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Addr Fam cont | Node address ~ | Addr Fam cont | Node address ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type : Protected Node Status Value Element (Type TBA-2 to be Type : Protected Node Status Value Element (Type TBA-2 to be
assigned by IANA) assigned by IANA)
Length: The Length field encodes the length of the Status Value Length: The Length field is an unsigned integer that encodes the
following the Length field. The encoded Length varies based on length of the Status Value following the Length field. The
the Address Family and is 6 octets (for Address Family + IPv4 encoded Length varies based on the Address Family and is 6 octets
address and 18 octets for Address Family + IPv6 address. (for Address Family + IPv4 address and 18 octets for Address
Family + IPv6 address.
Address Family: Two octet quantity containing a value from IANA's Addr Family: Two octet quantity containing a value from IANA's
"Address Family Numbers" registry that encodes the address family [AFI] registry that encodes the address family for the Node
for the Node Address. Address.
Node address: Protected node address encoded according to Address Node address: Protected node address encoded according to Address
Family field. Family field.
When a PLR receives a Label Mapping for FEC <R,X> that includes a When a PLR receives a Label Mapping for FEC <R,X> that includes a
Protected Node Status, it will only use that label binding once the Protected Node Status, it will only use that label binding once the
Node advertised in the Status value becomes unreachable. If the LSP Node advertised in the Status value becomes unreachable. If the LSP
is a MP2MP LSP, the PLR would have assigned a Label Mapping for the is a MP2MP LSP, the PLR would have assigned a Label Mapping for the
upstream MP2MP FEC Element to the MPT ([RFC6388] section 3) for FEC upstream MP2MP FEC Element to the MPT ([RFC6388] section 3) for FEC
<R,X>. This label binding on the MPT MUST only be used once node N <R,X>. This label binding on the MPT MUST only be used once node N
becomes unreachable. becomes unreachable.
The procedures to determine if a node is unreachable is a local The procedures to determine if a node is unreachable is a local
decision and not spelled out in this draft. Typical link failure or decision and not spelled out in this draft. Typically link failure
Bidirectional Forwarding Detection (BFD) can be used to determine and or Bidirectional Forwarding Detection (BFD) can be used to determine
detect node unreachability. and detect node unreachability.
4. Link or node failure 4. Link or node failure
Consider the following topology; Consider the following topology;
root root
^ ^
| |
. (LSR1) . (LSR1)
. / | . . / | .
skipping to change at page 9, line 31 skipping to change at page 10, line 29
. / \. . / \.
(LSR2) (LSR3) (LSR2) (LSR3)
| | | |
Figure 3. Figure 3.
N: The node being protected N: The node being protected
M: The backup node to protect link LSR1 - N M: The backup node to protect link LSR1 - N
...; Backup LSPs from LSR1 to LSR2 and LSR3. ...; Backup LSPs from LSR1 to LSR2 and LSR3.
Assume that LSR1 is the PLR for protected node N, LSR2 and LSR3 are Assume that LSR1 is the PLR for protected node N, LSR2 and LSR3 are
MPTs for node N. When LSR1 discovered that node N is unreachable, it MPTs for node N. When LSR1 discovers that node N is unreachable, it
can't determine whether it is the 'LSR1 - N' link or node N that cannot immediately determine whether it is the link from LSR1 to N or
failed. In Figure 3, the link between LSR1 and N is also protected the actual node N that has failed. In Figure 3, the link between
using Fast ReRoute (FRR) [RFC4090] link protection via node M. LSR1 LSR1 and N is also protected using Fast ReRoute (FRR) [RFC4090] link
MAY potentially invoke 2 protection mechanisms at the same time, protection via node M. LSR1 MAY potentially invoke both protection
redirection the traffic due to link protection via node M to N, and mechanisms at the same time, that is redirection of the traffic using
for node protection directly to LSR1 and LSR2. If only the link link protection via node M to N, and for node protection directly to
failed, LSR2 and LSR3 will receive the packets twice due to the two LSR1 and LSR2. If only the link failed, LSR2 and LSR3 will receive
protection mechanisms. To prevent duplicate packets to be forwarded the packets twice due to the two protection mechanisms. To prevent
to the receivers on the tree, LSR2 and LSR3 need to determin which duplicate packets being forwarded to the receivers on the tree, LSR2
upstream node to accept the packets from. So, either from the and LSR3 need to determine from which upstream node they should
primary upstream LSR N or from the secondary upstream LSR1, but never accept the packets. This can be either from the primary upstream LSR
both at the same time. The selection between the primary upstream N or from the secondary upstream LSR1, but never both at the same
LSR or (one or more) secondary upstream LSRs (on LSR2 and LSR3) is time. The selection between the primary upstream LSR or (one or
based on the reachability of the protected node N. As long as N is more) secondary upstream LSRs (on LSR2 and LSR3) is based on the
reachable, N is the primary upstream LSR who is accepting the MPLS reachability of the protected node N. As long as N is reachable from
packets and forwarding them. Once N becomes unreachable, the an MPT, the MPT should accept and forward the MPLS packets from N.
secondary upstream LSRs (LSR1 in our example) are activated. Note Once N becomes unreachable, the LSPs from secondary upstream PLR LSRs
that detecting if N is unreachable is a local decision and not (LSR1 in our example) are activated. Note that detecting if N is
spelled out in this draft. Typical link failure or Bidirectional unreachable is a local decision and not spelled out in this draft.
Forwarding Detection (BFD) can be used to determine and detect node
unreachability. Typically link failure or Bidirectional Forwarding Detection (BFD)
can be used to determine and detect node unreachability.
4.1. Re-convergence after node/link failure 4.1. Re-convergence after node/link failure
Consider the following topology; Consider the following topology;
root root
^ ^
_ | _ |
/. (LSR1) /. (LSR1)
/. /. | .\ /. /. | .\
skipping to change at page 10, line 29 skipping to change at page 11, line 28
(P). \. | .\ (P). \. | .\
\. ( N ) .(Q) \. ( N ) .(Q)
\. / \ ./ \. / \ ./
\. / \ ./ \. / \ ./
(LSR2) (LSR3) (LSR2) (LSR3)
| | | |
Figure 4. Figure 4.
N: The node being protected. N: The node being protected.
M: The backup node to protect link 'LSR1 - N'. M: The backup node to protect link 'LSR1 - N'.
P and Q: The nodes on the new primary path after N failure. P and Q: The nodes on the new primary path after failure of node N.
...: P2P backup LSPs. ...: P2P backup LSPs.
Assume that LSR1 has detected that Node N is unreachable and invoked Assume that LSR1 has detected that Node N is unreachable and invoked
both the Link Protection and Node Protection procedures as described both the Link Protection and Node Protection procedures as described
in this draft. LSR1 is acting as PLR and sending traffic over both in this example. LSR1 is acting as PLR and sending traffic over both
the backup P2P LSP to node N (via M) and the P2P LSPs directly to the backup P2P LSP to node N (via M) and the P2P LSPs directly to
LSR2 and LSR3, acting as MPT LSRs. The sequence of events are LSR2 and LSR3, acting as MPT LSRs. The sequence of events is
depending on whether the link 'LSR1 - N' has failed or node N itself. dependent on whether the link from LSR1 to N has failed or node N
The node's downsteam from the protected node (and participating in itself. The nodes downstream from the protected node (and
node protection) MUST have the capability to determin that the participating in node protection) MUST have the capability to
protected node became unreachable. Otherwise the procedures below determine that the protected node has become unreachable. Otherwise
can not be applied. the procedures below can not be applied.
4.1.1. Node failure 4.1.1. Node failure
If node N failed, both LSR2 and LSR3 will have changed the primary If node N failed, both LSR2 and LSR3 will have changed the primary
upstream LSR to the secondary upstream LSR (LSR1) due to node N being upstream LSR to the secondary upstream LSR (LSR1) due to node N being
unreachable. With that, the label bindings previously assigned to unreachable. With that, the label bindings previously assigned to
LSR1 will be activated on the MPTs (LSR2 and LSR3) and the label LSR1 will be activated on the MPTs (LSR2 and LSR3) and the label
binding to N will be disabled. Traffic is now switched over the binding to N will be disabled. Traffic is now switched over to the
label bindings that where installed for node protection. label bindings that were installed for node protection.
4.1.2. Link failure 4.1.2. Link failure
If the link 'LSR1 - N' has failed, both LSR2 and LSR3 will not change If the link 'LSR1 - N' has failed, both LSR2 and LSR3 will not change
the primary upstream LSR because node N is still reachable. LSR2 and the primary upstream LSR because node N is still reachable. LSR2 and
LSR3 will receive traffic over two different bindings, the primary LSR3 will receive traffic over two different bindings, the primary
label binding assigned to node N (due to link protection via node M) label binding assigned to node N (due to link protection via node M)
as well as over the binding assigned to LSR1 for the node protection. as well as over the binding assigned to LSR1 for the node protection.
Since the secondary upstream LSRs have not been activated, the Since the secondary upstream LSRs have not been activated, the
traffic received due to node protection will be dropped. Node N will traffic received due to node protection will be dropped. Node N will
re-converge and update LSR2 and LSR3 (Section 2.3) with the re-converge and update LSR2 and LSR3 (Section 2.3) with the
information that the PLR address (LSR1) is no longer applicable and information that the PLR address (LSR1) is no longer applicable and
must be removed. In response, LSR2 and LSR3 MUST sent a Label must be removed. In response, LSR2 and LSR3 MUST send a Label
Withdraw to LSR1 to withdraw the label binding. This will stop the Withdraw to LSR1 to withdraw the label binding. This will stop the
traffic being forwarded over the backup P2P LSPs for node protection. traffic being forwarded over the backup P2P LSPs for node protection.
LSR1 will respond back with a Label Release as soon as the binding LSR1 will respond back with a Label Release as soon as the binding
has been removed. has been removed.
4.1.3. Switching to new primary path 4.1.3. Switching to new primary path
The network will eventually re-converge and a new best path to the The network will eventually re-converge and a new best path to the
root will be found by LSR2 and LSR3. LSR2 will find that P is its root will be found by LSR2 and LSR3. LSR2 will find that P is its
new primary upstream LSR to reach the Root and LSR3 will find Q. Note new primary upstream LSR to reach the Root and LSR3 will find Q. Note
skipping to change at page 11, line 50 skipping to change at page 12, line 50
When it is determined that after re-convergence there is no more When it is determined that after re-convergence there is no more
interest in the tLDP session between the MPT and the PLR, the tLDP interest in the tLDP session between the MPT and the PLR, the tLDP
session MAY be taken down. It is possible that having no more session MAY be taken down. It is possible that having no more
interest in the tLDP session is temporarily due to link flapping. In interest in the tLDP session is temporarily due to link flapping. In
order to avoid the tLDP session from flapping, it is RECOMMENDED to order to avoid the tLDP session from flapping, it is RECOMMENDED to
apply a delay before tearing down the session. Determining the delay apply a delay before tearing down the session. Determining the delay
is a local implementation matter. is a local implementation matter.
5. mLDP Capabilities for Node Protection 5. mLDP Capabilities for Node Protection
In order to describe the capabilities of the participating LSRs , we In order to describe the capabilities of the participating LSRs, this
are organizing it per role in the network i.e., Point of Local Repair document is organizing it per role in the network i.e., Point of
(PLR), Merge Point (MPT), and Protected Node (as depicted in Fig 1). Local Repair (PLR), Merge Point (MPT), and Protected Node (as
depicted in Fig 1).
5.1. PLR capability 5.1. PLR capability
A PLR node should handle the following conditions; A PLR node should handle the following conditions;
1. Accept an incoming tLDP session from the MPT LSR. 1. Accept an incoming tLDP session from the MPT LSR.
2. Support the receipt of a "Protected Node Status Value Element" 2. Support the receipt of a "Protected Node Status Value Element"
status in a MP Status TLV over tLDP session. status in a MP Status TLV over tLDP session.
skipping to change at page 12, line 35 skipping to change at page 13, line 36
An MPT node should handle the following conditions; An MPT node should handle the following conditions;
1. Support the receipt of "PLR Status Value Element" in a MP Status 1. Support the receipt of "PLR Status Value Element" in a MP Status
TLV from a protected node N. TLV from a protected node N.
2. Support to transmit "Protected Node Status Value Element" in a MP 2. Support to transmit "Protected Node Status Value Element" in a MP
Status TLV to a PLR. Status TLV to a PLR.
A LSR capable of performing these actions will advertise itself as A LSR capable of performing these actions will advertise itself as
the MPT capable in the Node Protection capability (see Section 5.4). MPT capable in the Node Protection capability (see Section 5.4).
This is a unidirectional capability from MPT to the protected LSR. This is a unidirectional capability from MPT to the protected LSR.
5.3. The Protected LSR 5.3. The Protected LSR
A protected node should handle the following conditions; A protected node should handle the following conditions;
1. Determine the PLR and MPT capability for directly connected 1. Determine the PLR and MPT capability for directly connected
upstream and downstream LSRs for a given MP FEC. upstream and downstream LSRs for a given MP FEC.
2. Support transmitting of "PLR Status Value Element" in a MP Status 2. Support transmitting of "PLR Status Value Element" in a MP Status
skipping to change at page 13, line 34 skipping to change at page 14, line 35
|S| Reserved |P|M| Reserved | |S| Reserved |P|M| Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Where Where
U/F bits: MUST be set to 1 and 0 respectively (as per [RFC5561]) U/F bits: MUST be set to 1 and 0 respectively (as per [RFC5561])
Type: MP Node Protection Capability (Type = TBA-3 to be assigned Type: MP Node Protection Capability (Type = TBA-3 to be assigned
by IANA) by IANA)
Length: MUST be set to 2. Length: Unsigned integer, MUST be set to 2.
S bit: Set to 1 to announce and 0 to withdraw the capability (as S bit: Set to 1 to announce and 0 to withdraw the capability (as
per [RFC5561]) per [RFC5561])
P bit: PLR capable for MP LSP node protection P bit: Set to 1 to indicate the PLR is capable of MP LSP node
protection
M bit: MPT capable for MP LSP node protection M bit: Set to 1 to indicate the MPT is capable of MP LSP node
protection
Reserved: Must be zero on transmit and ignored on receipt Reserved: MUST be zero on transmit and ignored on receipt
The above capability can be sent in an LDP Initialization message to The above capability can be sent in an LDP Initialization message to
announce capability at the session establishment time, or it can be announce capability at the session establishment time, or it can be
sent in LDP Capability message to dynamically update (announce or sent in LDP Capability message to dynamically update (announce or
withdraw) its capability towards its peer using procedures specified withdraw) its capability towards its peer using procedures specified
in [RFC5561]. in [RFC5561].
An LSR that supports the PLR functionality LSR MAY send this An LSR that supports the PLR functionality LSR MAY send this
capability to its downstream MP peers with "P" bit set; whereas, an capability to its downstream MP peers with "P" bit set; whereas, an
LSR that supports an the MPT functionality MAY send this capability LSR that supports an the MPT functionality MAY send this capability
skipping to change at page 14, line 42 skipping to change at page 15, line 44
Parameters. The lowest available new code point after 0x0970 should Parameters. The lowest available new code point after 0x0970 should
be used. be used.
Value | Description | Reference | Notes/Reg Date Value | Description | Reference | Notes/Reg Date
------+-------------------------------+-----------+--------------- ------+-------------------------------+-----------+---------------
TBA-3 | MP Node Protection Capability | This doc | TBA-3 | MP Node Protection Capability | This doc |
8. Acknowledgments 8. Acknowledgments
The authors like to thank Nagendra Kumar, Duan Hong, Martin The authors like to thank Nagendra Kumar, Duan Hong, Martin
Vigoureux, Kenji Fujihira and Loa Andersson for their comments on Vigoureux, Kenji Fujihira, Loa Andersson for their comments and Elwyn
this draft. Davies for his great review of this document.
9. References 9. Contributor Addresses
9.1. Normative References
Below is a list of other contributing authors in alphabetical order:
Eric Rosen
Juniper Networks, Inc.
10 Technology Park Drive
Westford
MA 01886
USA
erosen@juniper.net
10. References
10.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] 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.
[RFC5036] Andersson, L., Minei, I., and B. Thomas, "LDP [RFC5036] Andersson, L., Minei, I., and B. Thomas, "LDP
Specification", RFC 5036, October 2007. Specification", RFC 5036, October 2007.
[RFC6388] Wijnands, IJ., Minei, I., Kompella, K., and B. Thomas, [RFC6388] Wijnands, IJ., Minei, I., Kompella, K., and B. Thomas,
"Label Distribution Protocol Extensions for Point-to- "Label Distribution Protocol Extensions for Point-to-
Multipoint and Multipoint-to-Multipoint Label Switched Multipoint and Multipoint-to-Multipoint Label Switched
Paths", RFC 6388, November 2011. Paths", RFC 6388, November 2011.
[RFC5561] Thomas, B., Raza, K., Aggarwal, S., Aggarwal, R., and JL. [RFC5561] Thomas, B., Raza, K., Aggarwal, S., Aggarwal, R., and JL.
Le Roux, "LDP Capabilities", RFC 5561, July 2009. Le Roux, "LDP Capabilities", RFC 5561, July 2009.
[RFC7060] Napierala, M., Rosen, E., and IJ. Wijnands, "Using LDP [RFC7060] Napierala, M., Rosen, E., and IJ. Wijnands, "Using LDP
Multipoint Extensions on Targeted LDP Sessions", RFC 7060, Multipoint Extensions on Targeted LDP Sessions", RFC 7060,
November 2013. November 2013.
9.2. Informative References [AFI] "IANA, Address Family Identifier (AFIs), http://
www.iana.org/assignments/address-family-numbers/address-
family-numbers.xhtml", July 2013.
10.2. Informative References
[RFC4090] Pan, P., Swallow, G., and A. Atlas, "Fast Reroute [RFC4090] Pan, P., Swallow, G., and A. Atlas, "Fast Reroute
Extensions to RSVP-TE for LSP Tunnels", RFC 4090, Extensions to RSVP-TE for LSP Tunnels", RFC 4090,
May 2005. May 2005.
[RFC5920] Fang, L., "Security Framework for MPLS and GMPLS [RFC5920] Fang, L., "Security Framework for MPLS and GMPLS
Networks", RFC 5920, July 2010. Networks", RFC 5920, July 2010.
Authors' Addresses Authors' Addresses
skipping to change at page 16, line 4 skipping to change at page 17, line 14
Authors' Addresses Authors' Addresses
IJsbrand Wijnands (editor) IJsbrand Wijnands (editor)
Cisco Systems, Inc. Cisco Systems, Inc.
De kleetlaan 6a De kleetlaan 6a
Diegem 1831 Diegem 1831
Belgium Belgium
Email: ice@cisco.com Email: ice@cisco.com
Kamran Raza Kamran Raza
Cisco Systems, Inc. Cisco Systems, Inc.
2000 Innovation Drive 2000 Innovation Drive
Ottawa Ontario K2K-3E8 Ottawa Ontario K2K-3E8
Canada Canada
Email: skraza@cisco.com Email: skraza@cisco.com
Eric Rosen
Juniper Networks, Inc.
10 Technology Park Drive
Westford MA 01886
USA
Email: erosen@juniper.net
Alia Atlas Alia Atlas
Juniper Networks, Inc. Juniper Networks, Inc.
10 Technology Park Drive 10 Technology Park Drive
Westford MA 01886 Westford MA 01886
USA USA
Email: akatlas@juniper.net Email: akatlas@juniper.net
Jeff Tantsura Jeff Tantsura
Ericsson Ericsson
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