draft-wijnands-mpls-mldp-node-protection-03.txt   draft-wijnands-mpls-mldp-node-protection-04.txt 
Network Working Group IJ. Wijnands, Ed. Network Working Group IJ. Wijnands, Ed.
Internet-Draft E. Rosen Internet-Draft E. Rosen
Intended status: Standards Track K. Raza Intended status: Standards Track K. Raza
Expires: December 23, 2013 Cisco Systems, Inc. Expires: December 25, 2013 Cisco Systems, Inc.
J. Tantsura J. Tantsura
Ericsson Ericsson
A. Atlas A. Atlas
Juniper Networks Juniper Networks
Q. Quintin Q. Quintin
Huawei Technology Huawei Technology
June 21, 2013 June 23, 2013
mLDP Node Protection mLDP Node Protection
draft-wijnands-mpls-mldp-node-protection-03 draft-wijnands-mpls-mldp-node-protection-04
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) built by LDP ("Label Distribution Protocol"), or simply (MP LSPs) built by LDP ("Label Distribution Protocol"), or simply
mLDP. In order to protect a node N, the Point of Local Repair (PLR) mLDP. In order to protect a node N, the Point of Local Repair (PLR)
LSR of N must learn the Merge Point (MPT) LSR(s) of node N such that LSR of N must learn the Merge Point (MPT) LSR(s) of node N such that
traffic can be redirected to them in case node N fails. Redirecting traffic can be redirected to them in case node N fails. Redirecting
the traffic around the failed node N depends on existing P2P LSPs the traffic around the failed node N depends on existing P2P LSPs
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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 December 23, 2013. This Internet-Draft will expire on December 25, 2013.
Copyright Notice Copyright Notice
Copyright (c) 2013 IETF Trust and the persons identified as the Copyright (c) 2013 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 25 skipping to change at page 2, line 25
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 . . . . . . . . . . . . . . . . . 5
3. Using the T-LDP session . . . . . . . . . . . . . . . . . . . 7 3. Using the tLDP session . . . . . . . . . . . . . . . . . . . . 7
4. Link or node failure . . . . . . . . . . . . . . . . . . . . . 9 4. Link or node failure . . . . . . . . . . . . . . . . . . . . . 9
4.1. Re-convergence after node/link failure . . . . . . . . . . 10 4.1. Re-convergence after node/link failure . . . . . . . . . . 10
4.1.1. Node failure . . . . . . . . . . . . . . . . . . . . . 10 4.1.1. Node failure . . . . . . . . . . . . . . . . . . . . . 10
4.1.2. Link failure . . . . . . . . . . . . . . . . . . . . . 11 4.1.2. Link failure . . . . . . . . . . . . . . . . . . . . . 10
4.1.3. Switching to new primary path . . . . . . . . . . . . 11 4.1.3. Switching to new primary path . . . . . . . . . . . . 11
5. mLDP Capabilities for Node Protection . . . . . . . . . . . . 11 5. mLDP Capabilities for Node Protection . . . . . . . . . . . . 11
5.1. PLR capability . . . . . . . . . . . . . . . . . . . . . . 12 5.1. PLR capability . . . . . . . . . . . . . . . . . . . . . . 12
5.2. MPT capability . . . . . . . . . . . . . . . . . . . . . . 12 5.2. MPT capability . . . . . . . . . . . . . . . . . . . . . . 12
5.3. The Protected LSR . . . . . . . . . . . . . . . . . . . . 12 5.3. The Protected LSR . . . . . . . . . . . . . . . . . . . . 12
5.4. The Node Protection Capability . . . . . . . . . . . . . . 13 5.4. The Node Protection Capability . . . . . . . . . . . . . . 13
6. Security Considerations . . . . . . . . . . . . . . . . . . . 14 6. Security Considerations . . . . . . . . . . . . . . . . . . . 14
7. IANA considerations . . . . . . . . . . . . . . . . . . . . . 14 7. IANA considerations . . . . . . . . . . . . . . . . . . . . . 14
8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 14 8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 14
9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 14 9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 14
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mLDP. In order to protect a node N, the Point of Local Repair (PLR) mLDP. In order to protect a node N, the Point of Local Repair (PLR)
of N must learn the Merge Point (MPT) LSR(s) of node N such that of N must learn the Merge Point (MPT) LSR(s) of node N such that
traffic can be redirected to them in case node N fails. Redirecting traffic can be redirected to them in case node N fails. Redirecting
the traffic around the failed node N depends on existing P2P LSPs the traffic around the failed node N depends on existing P2P LSPs
originating from the PLR LSR to the MPT LSR(s) while bypassing node originating from the PLR LSR to the MPT LSR(s) while bypassing node
N. The procedures to setup these P2P LSPs are outside the scope of N. The procedures to setup these P2P LSPs are outside the scope of
this document, but one can imagine using RSVP-TE or LDP LFA based this document, but one can imagine using RSVP-TE or LDP LFA based
techniques to accomplish this. techniques to accomplish this.
The solution described in this document signals the MPT LSR(s) to the The solution described in this document signals the MPT LSR(s) to the
PLR LSR(s) via a Targeted LDP (T-LDP) session [RFC5036]. By having a PLR LSR(s) via a Targeted LDP (tLDP) session [RFC5036]. By having a
T-LDP session with the PLR, most of the (m)LDP features currently tLDP session with the PLR, most of the (m)LDP features currently
defined should just work, like Make-Before-Break (MBB), Graceful defined should just work, like Make-Before-Break (MBB), Graceful
Restart (GR), Typed Wildcard FEC support, etc. All this is achieved Restart (GR), Typed Wildcard FEC support, etc. All this is achieved
at the expense of having an additional T-LDP session between an MPT at the expense of having an additional tLDP session between an MPT
and PLR LSR. and PLR LSR.
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"
skipping to change at page 3, line 48 skipping to change at page 3, line 48
mLDP: Multipoint extensions to LDP. mLDP: Multipoint extensions to LDP.
PLR: Point of Local Repair (the LSR that redirects the traffic to PLR: Point of Local Repair (the LSR that redirects the traffic to
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).
T-LDP: Targeted LDP session. tLDP: Targeted LDP session.
MP LSP: Multi-Point LSP (either a P2MP or MP2MP LSP). MP LSP: Multi-Point LSP (either a P2MP or MP2MP LSP).
2. PLR Determination 2. PLR Determination
In order for a MPT to establish a T-LDP session with the PLR, it In order for a MPT to establish a tLDP session with the PLR, it first
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 PLR address responsibility of the protected node N to advertise the PLR address
to the MPT. The PLR address for a MP LSP on node N is the address of 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 root node of the upstream LDP peer, but only when node N is NOT the root node of
the MP2MP LSP. If node N is the root node, the procedures are the MP2MP LSP. 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 this enabled (e.g. by a user configuration) to support and implement this
feature. feature.
2.1. Transit node procedure 2.1. Transit node procedure
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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, where the MP status contains a new "PLR Status Value with MP Status, where the MP status contains a new "PLR Status Value
Element" that specifies the address of the PLR. 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 | Length | Address ~ | Type = TBA-1 | Length | Addr Family |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ Family | Num PLR entry | | | Addr Fam cont | Num PLR entry | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
| | | |
| PLR entry (0 or more) ~ | PLR entry (0 or more) ~
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Where Where
Type: PLR (Type=3 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 encodes the length of the Status Value
following the Length field. The encoded Length varies based on following the Length field. The encoded Length varies based on
the Address Family and the number of PLR entries. the Address Family and the number of PLR entries.
Address Family: Two octet quantity containing a value from IANA's Address Family: Two octet quantity containing a value from IANA's
"Address Family Numbers" registry that encodes the address family "Address Family Numbers" registry that encodes the address family
for the PLR Address encoded in the PLR entry. for the PLR Address encoded in the PLR entry.
Num PLR entry: Number of "PLR entries" encoded in the Status Value Num PLR entry: Number of "PLR entries" encoded in the Status Value
Element, followed by "Num PLR entry" field (please see format of a Element, followed by "Num PLR entry" field (please see format of a
PLR entry below). PLR entry 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) ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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. encoded in the PLR Status Value Element.
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address is likely due to a link failure, see the procedures as 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 MP Status a MP FEC TLV MUST be included in the LDP
Notification message so that a receiver is able to associate the PLR Notification message so that a receiver is able to associate the PLR
Status with the MP LSP. Status with the MP LSP.
3. Using the T-LDP 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 T-LDP 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
[I-D.ietf-mpls-targeted-mldp]. [I-D.ietf-mpls-targeted-mldp].
Using Figure 1 as the reference topology, let us assume that both Using Figure 1 as the reference topology, let us assume that both
LSR2 and LSR3 are MPTs and have established a T-LDP session with the LSR2 and LSR3 are MPTs and have established a tLDP session with the
PLR being LSR1. Assume that both LSR2 and LSR3 have a FEC <R,X> with PLR being LSR1. Assume that both LSR2 and LSR3 have a FEC <R,X> with
a upstream LSR N and label Ln assigned to FEC towards N. The MPTs a upstream LSR N and label Ln assigned to FEC towards N. The MPTs
will create a secondary upstream LSR (using the received PLR address) will create a secondary upstream LSR (using the received PLR address)
and assigned a Label Lpx to FEC <R,X> towards PLR for it. The MPTs and assigned a Label Lpx to FEC <R,X> towards PLR for it. The MPTs
will do that for each PLR address that was learned for the MP LSP. will do that for each PLR address that was learned for the MP LSP.
In this example, the MPTs will have a FEC <R,X> with two local labels In this example, the MPTs will have a FEC <R,X> with two local labels
associated with it. Ln that was assigned to N via the normal mLDP associated with it. Ln that was assigned to N via the normal mLDP
procedures, and Label Lpx that was assigned for PLR (LSR1) for the procedures, and Label Lpx that was assigned for PLR (LSR1) for the
purpose of node protecting MP LSP via node N. Note, when the purpose of node protecting MP LSP via node N. Note, when the
protected node is a MP2MP root node, there will be an upstream LSR protected node is a MP2MP root node, there will be an upstream LSR
for each PLR address that was advertised along with a unique Label for each PLR address that was advertised along with a unique Label
Lpx. Lpx.
It is not preferable that a PLR is always sending traffic to an MPT The receipt of a FEC Label Mapping alone over the tLDP session from
over the backup P2P LSP. The PLR should only send traffic over the MPT on a PLR conveys the label information but does not convey the
backup P2P LSP if node N fails. The receipt of a FEC Label Mapping node being protected. The information about a protected node is
alone over the T-LDP session from MPT on a PLR conveys the label known to the MPT LSR and needs to be communicated to the PLR as well.
information but does not convey the node being protected. The For this reason, the FEC Label Mapping (FEC <R,X> : Lpx) sent by the
information about a protected node is known to the MPT LSR and needs MPT over the tLDP session to the PLR MUST include a Status TLV with
to be communicated to the PLR as well. For this reason, the FEC MP Status including a new LDP MP status Value Element called the
Label Mapping (FEC <R,X> : Lpx) sent by the MPT over the T-LDP "Protected Node Status Value Element". This new value element is
session to the PLR MUST include a Status TLV with MP Status including used to specify the address of the node being protected. The
a new LDP MP status Value Element called the "Protected Node Status "Protected Node Status Value Element" has the following format;
Value Element". This new value element is used to specify the
address of the node being protected. The "Protected Node Status
Value Element" 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type = 4 | Length | Address Family | Type = TBA-2 | Length | Addr Family |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Node address ~ | Addr Fam cont | Node address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Node address continued |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ |
+-+-+-+-+-+-+-+-+
Type : Protected Node (Type = 4 to be assigned by IANA) Type : Protected Node Status Value Element (Type TBA-2 to be
assigned by IANA)
Length: The Length field encodes the length of the Status Value Length: The Length field encodes the length of the Status Value
following the Length field. The encoded Length varies based on following the Length field. The encoded Length varies based on
the Address Family and is 4 octets and 16 octets respectively for the Address Family and is 6 octets (for Address Family + IPv4
an IPv4 address and an IPv6 address. address and 18 octets for Address Family + IPv6 address.
Address Family: Two octet quantity containing a value from IANA's Address Family: Two octet quantity containing a value from IANA's
"Address Family Numbers" registry that encodes the address family "Address Family Numbers" registry that encodes the address family
for the Node Address. for the Node 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
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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
that although the current active upstream LSR can either be node N or that although the current active upstream LSR can either be node N or
LSR1 (depending on link or node failure), it does not matter for the LSR1 (depending on link or node failure), it does not matter for the
following procedures. Both LSR2 and LSR3 SHOULD use the Make-Before- following procedures. Both LSR2 and LSR3 SHOULD use the Make-Before-
Break (MBB) procedures as described in [RFC6388] section 8 to switch Break (MBB) procedures as described in [RFC6388] section 8 to switch
to the new primary upstream node. As soon as the new primary to the new primary upstream node. As soon as the new primary
upstream LSRs P and Q are activated, a Label Withdraw message MUST be upstream LSRs P and Q are activated, a Label Withdraw message MUST be
sent to the old upstream LSR. Note that an upstream LSR switchover sent to the old upstream LSR. Note that an upstream LSR switchover
from a T-LDP neighbor to a directly connected LDP neighbor is no from a tLDP neighbor to a directly connected LDP neighbor is no
different compared to switching between two directly connected different compared to switching between two directly connected
neighbors. After the Label Withdraw message has been received by neighbors. After the Label Withdraw message has been received by
LSR1 or node N, forwarding will stop and a Label Release will be LSR1 or node N, forwarding will stop and a Label Release will be
sent. sent.
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 T-LDP session between the MPT and the PLR, the T-LDP 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 T-LDP session is temporarily due to link flapping. interest in the tLDP session is temporarily due to link flapping. In
In order to avoid the T-LDP session from flapping, it is RECOMMENDED order to avoid the tLDP session from flapping, it is RECOMMENDED to
to apply a delay before tearing down the session. Determining the apply a delay before tearing down the session. Determining the delay
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 , we
are organizing it per role in the network i.e., Point of Local Repair are organizing it per role in the network i.e., Point of Local Repair
(PLR), Merge Point (MPT), and Protected Node (as depicted in Fig 1). (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 T-LDP 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 T-LDP session. status in a MP Status TLV over tLDP session.
3. Upon node failure detection, capable of switching traffic towards 3. Upon node failure detection, capable of switching traffic towards
one or more MPT(s) over P2P LSP (bypassing N) using the labels one or more MPT(s) over P2P LSP (bypassing N) using the labels
previously advertised for MP LSPs over the T-LDP session. previously advertised for MP LSPs over the tLDP session.
An LSR capable of performing these actions will advertise it self as An LSR capable of performing these actions will advertise it self as
PLR capable in the Node Protection capability (see Section 5.4). PLR capable in the Node Protection capability (see Section 5.4).
This is a unidirectional capability announced from PLR to the This is a unidirectional capability announced from PLR to the
protected LSR. protected LSR.
5.2. MPT capability 5.2. MPT capability
An MPT node should handle the following conditions; An MPT node should handle the following conditions;
skipping to change at page 13, line 9 skipping to change at page 13, line 7
The protected LSR does not advertise any capability for mLDP Node The protected LSR does not advertise any capability for mLDP Node
Protection because it does not need to receive any of the defined MP Protection because it does not need to receive any of the defined MP
Status values as described above. However, the protected node does Status values as described above. However, the protected node does
play an important role in the signaling and setup of the node play an important role in the signaling and setup of the node
protection. For a given FEC, the protected node can only send PLR protection. For a given FEC, the protected node can only send PLR
information to a downstream LSR if the PLR has signaled the PLR information to a downstream LSR if the PLR has signaled the PLR
capability and the downstream LSR has signaled the MPT capability. capability and the downstream LSR has signaled the MPT capability.
When the downstream LSR (acting as MPT) receives the PLR status, it When the downstream LSR (acting as MPT) receives the PLR status, it
can implicitly infer that the advertised LSR(s) are PLR capable. The can implicitly infer that the advertised LSR(s) are PLR capable. The
MPT LSR can now proceed with setting up a T-LDP session with the MPT LSR can now proceed with setting up a tLDP session with the
PLR(s) and MP LSP node protection signaling. PLR(s) and MP LSP node protection signaling.
5.4. The Node Protection Capability 5.4. The Node Protection Capability
We define a single capability "MP Node Protection Capability" to We define a single capability "MP Node Protection Capability" to
announce the PLR and MPT capability. announce the PLR and MPT capability.
The format of the capability parameter TLV is as follows: The format of the capability parameter TLV 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|U|F| MP Node Prot Cap. (IANA) | Length = 2 | |U|F| Type = TBA-3 | Length = 2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|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 [RF5561]) U/F bits: MUST be set to 1 and 0 respectively (as per [RFC5561])
MP Node Protection Capability: TLV type (value to be assigned by Type: MP Node Protection Capability (Type = TBA-3 to be assigned
IANA) by IANA)
Length: MUST be set to 2. Length: 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: PLR capable for MP LSP node protection
M bit: MPT capable for MP LSP node protection M bit: MPT capable for MP LSP node protection
skipping to change at page 14, line 20 skipping to change at page 14, line 17
to its peers with both "P" and "M" bit set. to its peers with both "P" and "M" bit set.
6. Security Considerations 6. Security Considerations
The same security considerations apply as those for the base mLDP The same security considerations apply as those for the base mLDP
specification, as described in [RFC6388]. specification, as described in [RFC6388].
7. IANA considerations 7. IANA considerations
IANA is requested to allocate two new code points from the "LDP MP IANA is requested to allocate two new code points from the "LDP MP
Status Value Element type" registry; Status Value Element type" registry within the Label Distribution
Protocol (LDP) Parameters;
PLR Status Value Element - 3
Protected Node Status Value Element - 4 Value | Name | Reference
------+----------------------------------------+-----------
TBA-1 | PLR Status Value Element | this doc
------+----------------------------------------+-----------
TBA-2 | Protected Node Status Value Element | this doc
IANA is requested to assign one new code points for a new Capability IANA is requested to assign a new code points for a new Capability
Parameter TLVs from the LDP registry "TLV Type Name Space", Parameter TLV. The code point should be assigned from the IETF
corresponding to the advertisement of the the new MP Status values. Consensus range of the "TLV Type Name Space" registry within the LDP
The values is: Parameters. The lowest available new code point after 0x0970 should
be used.
MP Node Protection Capability - TBD Value | Description | Reference | Notes/Reg Date
------+-------------------------------+-----------+---------------
TBA-3 | MP Node Protection Capability | This doc |
8. Acknowledgments 8. Acknowledgments
The authors like to thank Nagendra Kumar, Duan Hong, Martin Vigoureux The authors like to thank Nagendra Kumar, Duan Hong, Martin
and Kenji Fujihira for their comments on this draft. Vigoureux, Kenji Fujihira and Loa Andersson for their comments on
this draft.
9. References 9. References
9.1. Normative References 9.1. 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.
skipping to change at page 15, line 14 skipping to change at page 15, line 19
"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.
[I-D.ietf-mpls-targeted-mldp] [I-D.ietf-mpls-targeted-mldp]
Napierala, M. and E. Rosen, "Using LDP Multipoint Napierala, M. and E. Rosen, "Using LDP Multipoint
Extensions on Targeted LDP Sessions", Extensions on Targeted LDP Sessions",
draft-ietf-mpls-targeted-mldp-00 (work in progress), draft-ietf-mpls-targeted-mldp-01 (work in progress),
August 2012. January 2013.
9.2. Informative References 9.2. 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.
Authors' Addresses Authors' Addresses
IJsbrand Wijnands (editor) IJsbrand Wijnands (editor)
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