draft-ietf-rtgwg-lfa-manageability-01.txt   draft-ietf-rtgwg-lfa-manageability-02.txt 
Routing Area Working Group S. Litkowski Routing Area Working Group S. Litkowski
Internet-Draft B. Decraene Internet-Draft B. Decraene
Intended status: Standards Track Orange Intended status: Standards Track Orange
Expires: July 26, 2014 C. Filsfils Expires: August 7, 2014 C. Filsfils
K. Raza K. Raza
Cisco Systems Cisco Systems
M. Horneffer M. Horneffer
Deutsche Telekom Deutsche Telekom
P. Sarkar P. Sarkar
Juniper Networks Juniper Networks
January 22, 2014 February 3, 2014
Operational management of Loop Free Alternates Operational management of Loop Free Alternates
draft-ietf-rtgwg-lfa-manageability-01 draft-ietf-rtgwg-lfa-manageability-02
Abstract Abstract
Loop Free Alternates (LFA), as defined in RFC 5286 is an IP Fast Loop Free Alternates (LFA), as defined in RFC 5286 is an IP Fast
ReRoute (IP FRR) mechanism enabling traffic protection for IP traffic ReRoute (IP FRR) mechanism enabling traffic protection for IP traffic
(and MPLS LDP traffic by extension). Following first deployment (and MPLS LDP traffic by extension). Following first deployment
experiences, this document provides operational feedback on LFA, experiences, this document provides operational feedback on LFA,
highlights some limitations, and proposes a set of refinements to highlights some limitations, and proposes a set of refinements to
address those limitations. It also proposes required management address those limitations. It also proposes required management
specifications. specifications.
This proposal is also applicable to remote LFA solution. This proposal is also applicable to remote LFA solution.
Requirements Language Requirements Language
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 [RFC2119]. document are to be interpreted as described in [RFC2119].
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 July 26, 2014. This Internet-Draft will expire on August 7, 2014.
Copyright Notice Copyright Notice
Copyright (c) 2014 IETF Trust and the persons identified as the Copyright (c) 2014 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
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described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Operational issues with default LFA tie breakers . . . . . . 3 2. Operational issues with default LFA tie breakers . . . . . . . 4
2.1. Case 1: Edge router protecting core failures . . . . . . 3 2.1. Case 1: Edge router protecting core failures . . . . . . . 5
2.2. Case 2: Edge router choosen to protect core failures 2.2. Case 2: Edge router choosen to protect core failures
while core LFA exists . . . . . . . . . . . . . . . . . . 5 while core LFA exists . . . . . . . . . . . . . . . . . . 6
2.3. Case 3: suboptimal core alternate choice . . . . . . . . 5 2.3. Case 3: suboptimal core alternate choice . . . . . . . . . 7
2.4. Case 4: ISIS overload bit on LFA computing node . . . . . 6 2.4. Case 4: ISIS overload bit on LFA computing node . . . . . 8
3. Configuration requirements . . . . . . . . . . . . . . . . . 7 3. Need for coverage monitoring . . . . . . . . . . . . . . . . . 8
3.1. LFA enabling/disabling scope . . . . . . . . . . . . . . 7 4. Need for LFA activation granularity . . . . . . . . . . . . . 9
3.2. Policy based LFA selection . . . . . . . . . . . . . . . 8 5. Configuration requirements . . . . . . . . . . . . . . . . . . 9
3.2.1. Connected vs remote alternates . . . . . . . . . . . 8 5.1. LFA enabling/disabling scope . . . . . . . . . . . . . . . 9
3.2.2. Mandatory criteria . . . . . . . . . . . . . . . . . 9 5.2. Policy based LFA selection . . . . . . . . . . . . . . . . 10
3.2.3. Enhanced criteria . . . . . . . . . . . . . . . . . . 9 5.2.1. Connected vs remote alternates . . . . . . . . . . . . 10
3.2.4. Retrieving alternate path attributes . . . . . . . . 10 5.2.2. Mandatory criteria . . . . . . . . . . . . . . . . . . 11
3.2.5. Details on criterions . . . . . . . . . . . . . . . . 11 5.2.3. Enhanced criteria . . . . . . . . . . . . . . . . . . 11
4. Operational aspects . . . . . . . . . . . . . . . . . . . . . 16 5.2.4. Retrieving alternate path attributes . . . . . . . . . 11
4.1. ISIS overload bit on LFA computing node . . . . . . . . . 16 5.2.5. ECMP LFAs . . . . . . . . . . . . . . . . . . . . . . 13
4.2. Manual triggering of FRR . . . . . . . . . . . . . . . . 17 5.2.6. SRLG . . . . . . . . . . . . . . . . . . . . . . . . . 14
4.3. Required local information . . . . . . . . . . . . . . . 17 5.2.7. Link coloring . . . . . . . . . . . . . . . . . . . . 15
4.4. Coverage monitoring . . . . . . . . . . . . . . . . . . . 17 5.2.8. Bandwidth . . . . . . . . . . . . . . . . . . . . . . 16
4.5. Deterministic and documents LFA selection behavior . . . 18 5.2.9. Neighbor preference . . . . . . . . . . . . . . . . . 17
5. Security Considerations . . . . . . . . . . . . . . . . . . . 19 6. Operational aspects . . . . . . . . . . . . . . . . . . . . . 18
6. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 19 6.1. ISIS overload bit on LFA computing node . . . . . . . . . 18
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 19 6.2. Manual triggering of FRR . . . . . . . . . . . . . . . . . 18
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 19 6.3. Required local information . . . . . . . . . . . . . . . . 19
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 19 6.4. Coverage monitoring . . . . . . . . . . . . . . . . . . . 20
9.1. Normative References . . . . . . . . . . . . . . . . . . 19 6.5. LFA and network planning . . . . . . . . . . . . . . . . . 20
9.2. Informative References . . . . . . . . . . . . . . . . . 19 7. Security Considerations . . . . . . . . . . . . . . . . . . . 21
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 20 8. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 21
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 21
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 21
11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 21
11.1. Normative References . . . . . . . . . . . . . . . . . . . 21
11.2. Informative References . . . . . . . . . . . . . . . . . . 21
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 23
1. Introduction 1. Introduction
Following the first deployments of Loop Free Alternates (LFA), this Following the first deployments of Loop Free Alternates (LFA), this
document provides feedback to the community about the management of document provides feedback to the community about the management of
LFA. LFA.
Section 2 provides real uses cases illustrating some limitations Section 2 provides real uses cases illustrating some limitations
and suboptimal behavior. and suboptimal behavior.
skipping to change at page 4, line 4 skipping to change at page 5, line 6
exist, RFC 5286 has favored the selection of the LFA providing the exist, RFC 5286 has favored the selection of the LFA providing the
best coverage of the failure cases. While this is indeed a goal, best coverage of the failure cases. While this is indeed a goal,
this is one among multiple and in some deployment this lead to the this is one among multiple and in some deployment this lead to the
selection of a suboptimal LFA. The following sections details real selection of a suboptimal LFA. The following sections details real
use cases of such limitations. use cases of such limitations.
Note that the use case of per-prefix LFA is assumed throughout this Note that the use case of per-prefix LFA is assumed throughout this
analysis. analysis.
2.1. Case 1: Edge router protecting core failures 2.1. Case 1: Edge router protecting core failures
R1 --------- R2 ---------- R3 --------- R4
| 1 100 1 |
| |
| 100 | 100
| |
| 1 100 1 |
R5 --------- R6 ---------- R7 --------- R8 -- R9 - PE1
| | | |
| 5k | 5k | 5k | 5k
| | | |
+--- n*PEx ---+ +---- PE2 ----+
|
|
PEy
Figure 1 R1 --------- R2 ---------- R3 --------- R4
| 1 100 1 |
| |
| 100 | 100
| |
| 1 100 1 |
R5 --------- R6 ---------- R7 --------- R8 -- R9 - PE1
| | | |
| 5k | 5k | 5k | 5k
| | | |
+--- n*PEx ---+ +---- PE2 ----+
|
|
PEy
Figure 1
Rx routers are core routers using n*10G links. PEs are connected Rx routers are core routers using n*10G links. PEs are connected
using links with lower bandwidth. using links with lower bandwidth. PEx are a set of PEs connected to
R5 and R6.
In figure 1, let us consider the traffic flowing from PE1 to PEx. In figure 1, let us consider the traffic flowing from PE1 to PEx.
The nominal path is R9-R8-R7-R6-PEx. Let us consider the failure of The nominal path is R9-R8-R7-R6-PEx. Let us consider the failure of
link R7-R8. For R8, R4 is not an LFA and the only available LFA is link R7-R8. For R8, R4 is not an LFA and the only available LFA is
PE2. PE2.
When the core link R8-R7 fails, R8 switches all traffic destined to When the core link R8-R7 fails, R8 switches all traffic destined to
all the PEx towards the edge node PE2. Hence an edge node and edge all the PEx towards the edge node PE2. Hence an edge node and edge
links are used to protect the failure of a core link. Typically, links are used to protect the failure of a core link. Typically,
edge links have less capacity than core links and congestion may edge links have less capacity than core links and congestion may
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* with LFA: traffic is partially dropped (but possibly * with LFA: traffic is partially dropped (but possibly
prioritized by a QoS mechanism). prioritized by a QoS mechanism).
Besides the congestion aspects of using an Edge router as an Besides the congestion aspects of using an Edge router as an
alternate to protect a core failure, a service provider may consider alternate to protect a core failure, a service provider may consider
this as a bad routing design and would like to prevent it. this as a bad routing design and would like to prevent it.
2.2. Case 2: Edge router choosen to protect core failures while core 2.2. Case 2: Edge router choosen to protect core failures while core
LFA exists LFA exists
R1 --------- R2 ------------ R3 --------- R4 R1 --------- R2 ------------ R3 --------- R4
| 1 100 | 1 | | 1 100 | 1 |
| | | | | |
| 100 | 30 | 30 | 100 | 30 | 30
| | | | | |
| 1 50 50 | 10 | | 1 50 50 | 10 |
R5 -------- R6 ---- R10 ---- R7 -------- R8 --- R9 - PE1 R5 -------- R6 ---- R10 ---- R7 -------- R8 --- R9 - PE1
| | \ | | | \ |
| 5000 | 5000 \ 5000 | 5000 | 5000 | 5000 \ 5000 | 5000
| | \ | | | \ |
+--- n*PEx --+ +----- PE2 ----+ +--- n*PEx --+ +----- PE2 ----+
| |
| |
PEy PEy
Figure 2 Figure 2
Rx routers are core routers meshed with n*10G links. PEs are meshed Rx routers are core routers meshed with n*10G links. PEs are meshed
using links with lower bandwidth. using links with lower bandwidth.
In the figure 2, let us consider the traffic coming from PE1 to PEx. In the figure 2, let us consider the traffic coming from PE1 to PEx.
Nominal path is R9-R8-R7-R6-PEx. Let us consider the failure of the Nominal path is R9-R8-R7-R10-R6-PEx. Let us consider the failure of
link R7-R8. For R8, R4 is a link-protecting LFA and PE2 is a node- the link R7-R8. For R8, R4 is a link-protecting LFA and PE2 is a
protecting LFA. PE2 is chosen as best LFA due to its better node-protecting LFA. PE2 is chosen as best LFA due to its better
protection type. Just like in case 1, this may lead to congestion on protection type. Just like in case 1, this may lead to congestion on
PE2 links upon LFA activation. PE2 links upon LFA activation.
2.3. Case 3: suboptimal core alternate choice 2.3. Case 3: suboptimal core alternate choice
+--- PE3 --+ +--- PE3 --+
/ \ / \
1000 / \ 1000 1000 / \ 1000
/ \ / \
+----- R1 ---------------- R2 ----+ +----- R1 ---------------- R2 ----+
| | 500 | | | | 500 | |
| 10 | | | 10 | 10 | | | 10
| | | | | | | |
R5 | 10 | 10 R7 R5 | 10 | 10 R7
| | | | | | | |
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+----- R1 ---------------- R2 ----+ +----- R1 ---------------- R2 ----+
| | 500 | | | | 500 | |
| 10 | | | 10 | 10 | | | 10
| | | | | | | |
R5 | 10 | 10 R7 R5 | 10 | 10 R7
| | | | | | | |
| 10 | | | 10 | 10 | | | 10
| | 500 | | | | 500 | |
+---- R3 ---------------- R4 -----+ +---- R3 ---------------- R4 -----+
\ / \ /
\ / 1000 \ / 1000
\ / \ /
+--- PE1 ---+ +--- PE1 ---+
Figure 3 Figure 3
Rx routers are core routers. R1-R2 and R3-R4 links are 1G links. Rx routers are core routers. R1-R2 and R3-R4 links are 1G links.
All others inter Rx links are 10G links. All others inter Rx links are 10G links.
In the figure above, let us consider the failure of link R1-R3. For In the figure above, let us consider the failure of link R1-R3. For
destination PE3, R3 has two possible alternates: destination PE3, R3 has two possible alternates:
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PE2. PE2.
On PE3, the loopfree condition is not satisified : 100 !< 45 + 45. On PE3, the loopfree condition is not satisified : 100 !< 45 + 45.
PE1 is thus not considered as an LFA. However thanks to the overload PE1 is thus not considered as an LFA. However thanks to the overload
bit set on PE3, we know that PE1 is loopfree so PE1 is an LFA to bit set on PE3, we know that PE1 is loopfree so PE1 is an LFA to
reach PE2. reach PE2.
In case of overload condition set on a node, LFA behavior must be In case of overload condition set on a node, LFA behavior must be
clarified. clarified.
3. Configuration requirements 3. Need for coverage monitoring
As per [RFC6571], LFA coverage highly depends on the used network
topology. Even if remote LFA ([I-D.ietf-rtgwg-remote-lfa]) extends
significantly the coverage of the basic LFA specification, there is
still some cases where protection would not be available. As network
topologies are constantly evolving (network extension, capacity
addings, latency optimization ...), the protection coverage may
change. Fast reroute functionality may be critical for some services
supported by the network, a service provider must constantly know
what protection coverage is currently available on the network.
Moreover, predicting the protection coverage in case of network
topology change is mandatory : using network simulation tool and
whatif scenarios functionnality, a service provider may be able to
evaluate protection coverage after a topology change and may be able
to adjust the topology change to cover the primary need (e.g. latency
optimization or bandwidth increase) as well as LFA protection.
4. Need for LFA activation granularity
As all FRR mechanism, LFA installs backup paths in FIB. Depending of
the hardware used by a service provider, FIB ressource may be
critical. Activating LFA, by default, on all available components
(IGP topologies, interface, address families ...) may lead to waste
of FIB ressource as generally in a network only few destinations
should be protected (e.g. loopback addresses supporting MPLS
services) compared to the amount of destinations in RIB.
Moreover a service provider may implement multiple different FRR
mechanism in its networks for different usages (MRT, TE FRR),
computing LFAs for prefixes or interfaces that are already protected
by another mechanism is useless.
5. Configuration requirements
Controlling best alternate and LFA activation granularity is a Controlling best alternate and LFA activation granularity is a
requirement for Service Providers. This section defines requirement for Service Providers. This section defines
configuration requirements for LFA. configuration requirements for LFA.
3.1. LFA enabling/disabling scope 5.1. LFA enabling/disabling scope
The granularity of LFA activation should be controlled (as alternate The granularity of LFA activation should be controlled (as alternate
nexthop consume memory in forwarding plane). nexthop consume memory in forwarding plane).
An implementation of LFA SHOULD allow its activation with the An implementation of LFA SHOULD allow its activation with the
following criteria: following criteria:
o Per address-family : ipv4 unicast, ipv6 unicast, LDP IPv4 unicast, o Per address-family : ipv4 unicast, ipv6 unicast, LDP IPv4 unicast,
LDP IPv6 unicast ... LDP IPv6 unicast ...
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o Per address-family : ipv4 unicast, ipv6 unicast, LDP IPv4 unicast, o Per address-family : ipv4 unicast, ipv6 unicast, LDP IPv4 unicast,
LDP IPv6 unicast ... LDP IPv6 unicast ...
o Per routing context : VRF, virtual/logical router, global routing o Per routing context : VRF, virtual/logical router, global routing
table, ... table, ...
o Per interface o Per interface
o Per protocol instance, topology, area o Per protocol instance, topology, area
o Per prefixes: prefix protection SHOULD have a better priority o Per prefixes: prefix protection SHOULD have a better priority
compared to interface protection. This means that if a specific compared to interface protection. This means that if a specific
prefix must be protected due to a configuration request, LFA must prefix must be protected due to a configuration request, LFA must
be computed and installed for this prefix even if the primary be computed and installed for this prefix even if the primary
outgoing interface is not configured for protection. outgoing interface is not configured for protection.
3.2. Policy based LFA selection 5.2. Policy based LFA selection
When multiple alternates exist, LFA selection algorithm is based on When multiple alternates exist, LFA selection algorithm is based on
tie breakers. Current tie breakers do not provide sufficient control tie breakers. Current tie breakers do not provide sufficient control
on how the best alternate is chosen. This document proposes an on how the best alternate is chosen. This document proposes an
enhanced tie breaker allowing service providers to manage all enhanced tie breaker allowing service providers to manage all
specific cases: specific cases:
1. An implementation of LFA SHOULD support policy-based decision for 1. An implementation of LFA SHOULD support policy-based decision for
determining the best LFA. determining the best LFA.
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5. It is an implementation choice to reevaluate policy dynamically 5. It is an implementation choice to reevaluate policy dynamically
or not (in case of policy change). If a dynamic approach is or not (in case of policy change). If a dynamic approach is
chosen, the implementation SHOULD recompute the best LFAs and chosen, the implementation SHOULD recompute the best LFAs and
reinstall them in FIB, without service disruption. If a non- reinstall them in FIB, without service disruption. If a non-
dynamic approach is chosen, the policy would be taken into dynamic approach is chosen, the policy would be taken into
account upon the next IGP event. In this case, the account upon the next IGP event. In this case, the
implementation SHOULD support a command to manually force the implementation SHOULD support a command to manually force the
recomputation/reinstallation of LFAs. recomputation/reinstallation of LFAs.
3.2.1. Connected vs remote alternates 5.2.1. Connected vs remote alternates
In addition to direct LFAs, tunnels (e.g. IP, LDP or RSVP-TE) to In addition to direct LFAs, tunnels (e.g. IP, LDP or RSVP-TE) to
distant routers may be used to complement LFA coverage (tunnel tail distant routers may be used to complement LFA coverage (tunnel tail
used as virtual neighbor). When a router has multiple alternate used as virtual neighbor). When a router has multiple alternate
candidates for a specific destination, it may have connected candidates for a specific destination, it may have connected
alternates and remote alternates reachable via a tunnel. Connected alternates and remote alternates reachable via a tunnel. Connected
alternates may not always provide an optimal routing path and it may alternates may not always provide an optimal routing path and it may
be preferable to select a remote alternate over a connected be preferable to select a remote alternate over a connected
alternate. The usage of tunnels to extend LFA coverage is described alternate. The usage of tunnels to extend LFA coverage is described
in [I-D.ietf-rtgwg-remote-lfa]. in [I-D.ietf-rtgwg-remote-lfa].
In figure 1, there is no core alternate for R8 to reach PEs located In figure 1, there is no core alternate for R8 to reach PEs located
behind R6, so R8 is using PE2 as alternate, which may generate behind R6, so R8 is using PE2 as alternate, which may generate
congestion when FRR is activated. Instead, we could have a remote congestion when FRR is activated. Instead, we could have a remote
core alternate for R8 to protect PEs destinations. For example, a core alternate for R8 to protect PEs destinations. For example, a
tunnel from R8 to R3 would ensure LFA protection without using an tunnel from R8 to R3 would ensure LFA protection without using an
edge router to protect a core router. edge router to protect a core router.
When selecting the best alternate, the selection algorithm MUST When selecting the best alternate, the selection algorithm MUST
consider all available alternates (connected or tunnel). Especially, consider all available alternates (connected or tunnel). Especially,
computation of PQ set ([I-D.ietf-rtgwg-remote-lfa]) SHOULD to be computation of PQ set ([I-D.ietf-rtgwg-remote-lfa]) SHOULD be
performed before best alternate selection. performed before best alternate selection.
3.2.2. Mandatory criteria 5.2.2. Mandatory criteria
An implementation of LFA MUST support the following criteria: An implementation of LFA MUST support the following criteria:
o Non candidate link: A link marked as "non candidate" will never be o Non candidate link: A link marked as "non candidate" will never be
used as LFA. used as LFA.
o A primary nexthop being protected by another primary nexthop of o A primary nexthop being protected by another primary nexthop of
the same prefix (ECMP case). the same prefix (ECMP case).
o Type of protection provided by the alternate: link protection, o Type of protection provided by the alternate: link protection,
node protection. In case of node protection preference, an node protection. In case of node protection preference, an
implementation SHOULD support fallback to link protection if node implementation SHOULD support fallback to link protection if node
protection is not available. protection is not available.
o Shortest path: lowest IGP metric used to reach the destination. o Shortest path: lowest IGP metric used to reach the destination.
o SRLG (as defined in [RFC5286] Section 3). o SRLG (as defined in [RFC5286] Section 3).
3.2.3. Enhanced criteria 5.2.3. Enhanced criteria
An implementation of LFA SHOULD support the following enhanced An implementation of LFA SHOULD support the following enhanced
criteria: criteria:
o Downstreamness of a neighbor : preference of a downstream path o Downstreamness of a neighbor : preference of a downstream path
over a non downstream path SHOULD be configurable. over a non downstream path SHOULD be configurable.
o Link coloring with : include, exclude and preference based system. o Link coloring with : include, exclude and preference based system.
o Link Bandwidth. o Link Bandwidth.
o Neighbor preference. o Neighbor preference.
3.2.4. Retrieving alternate path attributes 5.2.4. Retrieving alternate path attributes
The policy to select the best alternate evaluate multiple criterions The policy to select the best alternate evaluate multiple criterions
(e.g. metric, SRLG, link colors ...) which first need to be computed (e.g. metric, SRLG, link colors ...) which first need to be computed
for each alternate.. In order to compare the different alternate for each alternate.. In order to compare the different alternate
path, a router must retrieve the attributes of each alternate path. path, a router must retrieve the attributes of each alternate path.
The alternate path is composed of two distinct parts : PLR to The alternate path is composed of two distinct parts : PLR to
alternate and alternate to destination. alternate and alternate to destination.
3.2.4.1. Connected alternate 5.2.4.1. Connected alternate
For alternate path using a connected alternate : For alternate path using a connected alternate :
o attributes from PLR to alternate path are retrieved from the o attributes from PLR to alternate path are retrieved from the
interface connected to the alternate. interface connected to the alternate.
o attributes from alternate to destination path are retrieved from o attributes from alternate to destination path are retrieved from
SPF rooted at the alternate. As the alternate is a connected SPF rooted at the alternate. As the alternate is a connected
alternate, the SPF has already been computed to find the alternate, the SPF has already been computed to find the
alternate, so there is no need of additional computation. alternate, so there is no need of additional computation.
3.2.4.2. Remote alternate 5.2.4.2. Remote alternate
For alternate path using a remote alternate (tunnel) : For alternate path using a remote alternate (tunnel) :
o attributes from the PLR to alternate path are retrieved using the o attributes from the PLR to alternate path are retrieved using the
PLR's primary SPF if P space is used or using the neighbor's SPF PLR's primary SPF if P space is used or using the neighbor's SPF
if extended P space is used, combined with the attributes of the if extended P space is used, combined with the attributes of the
link(s) to reach that neighbor. In both cases, no additional SPF link(s) to reach that neighbor. In both cases, no additional SPF
is required. is required.
o attributes from alternate to destination path are retrieved from o attributes from alternate to destination path are retrieved from
skipping to change at page 10, line 48 skipping to change at page 12, line 42
required for each remote alternate as indicated in required for each remote alternate as indicated in
[I-D.psarkar-rtgwg-rlfa-node-protection] section 3.2.. [I-D.psarkar-rtgwg-rlfa-node-protection] section 3.2..
The number of remote alternates may be very high, simulations shown The number of remote alternates may be very high, simulations shown
that hundred's of PQs may exist for a single interface being that hundred's of PQs may exist for a single interface being
protected. Running a forward SPF for every PQ-node in the network is protected. Running a forward SPF for every PQ-node in the network is
not scalable. not scalable.
To handle this situation, it is needed to limit the number of remote To handle this situation, it is needed to limit the number of remote
alternates to be evaluated to a finite number before collecting alternates to be evaluated to a finite number before collecting
alternate path attributes and running the policy evaluation. [I-D alternate path attributes and running the policy evaluation.
.psarkar-rtgwg-rlfa-node-protection] Section 2.3.3 provides a way to [I-D.psarkar-rtgwg-rlfa-node-protection] Section 2.3.3 provides a way
reduce the number of PQ to be evaluated. to reduce the number of PQ to be evaluated.
Link Remote Remote Link Remote Remote
alternate alternate alternate alternate alternate alternate
------------- ------------------ ------------- ------------- ------------------ -------------
Alternates | LFA | | rLFA (PQs) | | Static | Alternates | LFA | | rLFA (PQs) | | Static |
sources | | | | | tunnels | sources | | | | | tunnels |
------------- ------------------ ------------- ------------- ------------------ -------------
| | | | | |
| | | | | |
| ---------------------- | | ---------------------- |
skipping to change at page 11, line 31 skipping to change at page 13, line 31
------------------------------------------------ ------------------------------------------------
| |
| |
------------------------- -------------------------
| Evaluate policy | | Evaluate policy |
------------------------- -------------------------
| |
| |
Best alternates Best alternates
3.2.5. Details on criterions 5.2.5. ECMP LFAs
3.2.5.1. LFA and ECMP
10 10
PE2 - PE3 PE2 - PE3
| | | |
50 | 5 | 50 50 | 5 | 50
P1----P2 P1----P2
\\ // \\ //
50 \\ // 50 50 \\ // 50
PE1 PE1
Figure 5 Figure 5
Links between P1 and PE1 are L1 and L2, links between P2 and PE1 are Links between P1 and PE1 are L1 and L2, links between P2 and PE1 are
L3 and L4 L3 and L4
In the figure above, primary path from PE1 to PE2 is through P1 using In the figure above, primary path from PE1 to PE2 is through P1 using
ECMP on two parallel links L1 and L2. In case of standard ECMP ECMP on two parallel links L1 and L2. In case of standard ECMP
behavior, if L1 is failing, postconvergence nexthop would become L2 behavior, if L1 is failing, postconvergence nexthop would become L2
and there would be no longer ECMP. If LFA is activated, as stated in and there would be no longer ECMP. If LFA is activated, as stated in
[RFC5286] Section 3.4., "alternate next-hops may themselves also be [RFC5286] Section 3.4., "alternate next-hops may themselves also be
primary next-hops, but need not be" and "alternate next-hops should primary next-hops, but need not be" and "alternate next-hops should
maximize the coverage of the failure cases". In this scenario there maximize the coverage of the failure cases". In this scenario there
is no alternate providing node protection, LFA will so prefer L2 as is no alternate providing node protection, LFA will so prefer L2 as
alternate to protect L1 which makes sense compared to postconvergence alternate to protect L1 which makes sense compared to postconvergence
behavior. behavior.
Considering a different scenario using figure 5, where L1 and L2 are Considering a different scenario using figure 5, where L1 and L2 are
configured as a layer 3 bundle using a local feature, as well as L3/ configured as a layer 3 bundle using a local feature, as well as
L4 being a second layer 3 bundle. Layer 3 bundles are configured as L3/L4 being a second layer 3 bundle. Layer 3 bundles are configured
if a link in the bundle is failing, the traffic must be rerouted out as if a link in the bundle is failing, the traffic must be rerouted
of the bundle. Layer 3 bundles are generally introduced to increase out of the bundle. Layer 3 bundles are generally introduced to
bandwidth between nodes. In nominal situation, ECMP is still increase bandwidth between nodes. In nominal situation, ECMP is
available from PE1 to PE2, but if L1 is failing, postconvergence still available from PE1 to PE2, but if L1 is failing,
nexthop would become ECMP on L3 and L4. In this case, LFA behavior postconvergence nexthop would become ECMP on L3 and L4. In this
SHOULD be adapted in order to reflect the bandwidth requirement. case, LFA behavior SHOULD be adapted in order to reflect the
bandwidth requirement.
We would expect the following FIB entry on PE1 : We would expect the following FIB entry on PE1 :
On PE1 : PE2 +--> ECMP -> L1 On PE1 : PE2 +--> ECMP -> L1
| | | |
| +----> L2 | +----> L2
| |
+--> LFA(ECMP) -> L3 +--> LFA(ECMP) -> L3
| |
+---------> L4 +---------> L4
skipping to change at page 12, line 46 skipping to change at page 14, line 44
ECMP by another primary nexthop is not a MUST. Moreover, we already ECMP by another primary nexthop is not a MUST. Moreover, we already
presented in this document, that maximizing the coverage of the presented in this document, that maximizing the coverage of the
failure case may not be the right approach and policy based choice of failure case may not be the right approach and policy based choice of
alternate may be preferred. alternate may be preferred.
An implementation SHOULD permit to prefer a primary nexthop by An implementation SHOULD permit to prefer a primary nexthop by
another primary nexthop with the possibility to deactivate this another primary nexthop with the possibility to deactivate this
criteria. An implementation SHOULD permit to use an ECMP bundle as a criteria. An implementation SHOULD permit to use an ECMP bundle as a
LFA. LFA.
3.2.5.2. SRLG 5.2.6. SRLG
[RFC5286] Section 3. proposes to reuse GMPLS IGP extensions to encode [RFC5286] Section 3. proposes to reuse GMPLS IGP extensions to encode
SRLGs ([RFC4205] and [RFC4203]). The section is also describing the SRLGs ([RFC4205] and [RFC4203]). The section is also describing the
algorithm to compute SRLG protection. algorithm to compute SRLG protection.
When SRLG protection is computed, and implementation SHOULD permit to When SRLG protection is computed, and implementation SHOULD permit to
: :
o Exclude alternates violating SRLG. o Exclude alternates violating SRLG.
o Maintain a preference system between alternates based on number of o Maintain a preference system between alternates based on number of
SRLG violations : more violations = less preference. SRLG violations : more violations = less preference.
When applying SRLG criteria, the SRLG violation check SHOULD be When applying SRLG criteria, the SRLG violation check SHOULD be
performed on source to alternate as well as alternate to destination performed on source to alternate as well as alternate to destination
paths. In the case of remote LFA, PQ to destination path attributes paths. In the case of remote LFA, PQ to destination path attributes
would be retrieved from SPT rooted at PQ. would be retrieved from SPT rooted at PQ.
3.2.5.3. Link coloring 5.2.7. Link coloring
Link coloring is a powerful system to control the choice of Link coloring is a powerful system to control the choice of
alternates. Protecting interfaces are tagged with colors. Protected alternates. Protecting interfaces are tagged with colors. Protected
interfaces are configured to include some colors with a preference interfaces are configured to include some colors with a preference
level, and exclude others. level, and exclude others.
Link color information SHOULD be signalled in the IGP. How Link color information SHOULD be signalled in the IGP. How
signalling is done is out of scope of the document but it may be signalling is done is out of scope of the document but it may be
useful to reuse existing admin-groups from traffic-engineering useful to reuse existing admin-groups from traffic-engineering
extensions. extensions.
PE2 PE2
| +---- P4 | +---- P4
| / | /
PE1 ---- P1 --------- P2 PE1 ---- P1 --------- P2
| 10Gb | 10Gb
1Gb | 1Gb |
| |
P3 P3
Figure 5 Figure 5
Example : P1 router is connected to three P routers and two PEs. Example : P1 router is connected to three P routers and two PEs.
P1 is configured to protect the P1-P4 link. We assume that given the P1 is configured to protect the P1-P4 link. We assume that given the
topology, all neighbors are candidate LFA. We would like to enforce topology, all neighbors are candidate LFA. We would like to enforce
a policy in the network where only a core router may protect against a policy in the network where only a core router may protect against
the failure of a core link, and where high capacity links are the failure of a core link, and where high capacity links are
prefered. prefered.
In this example, we can use the proposed link coloring by: In this example, we can use the proposed link coloring by:
skipping to change at page 14, line 35 skipping to change at page 16, line 38
An implementation of link coloring: An implementation of link coloring:
o SHOULD support multiple include and exclude colors on a single o SHOULD support multiple include and exclude colors on a single
protected interface. protected interface.
o SHOULD provide a level of preference between included colors. o SHOULD provide a level of preference between included colors.
o SHOULD support multiple colors configuration on a single o SHOULD support multiple colors configuration on a single
protecting interface. protecting interface.
3.2.5.4. Bandwidth 5.2.8. Bandwidth
As mentionned in previous sections, not taking into account bandwidth As mentionned in previous sections, not taking into account bandwidth
of an alternate could lead to congestion during FRR activation. We of an alternate could lead to congestion during FRR activation. We
propose to base the bandwidth criteria on the link speed information propose to base the bandwidth criteria on the link speed information
for the following reason : for the following reason :
o if a router S has a set of X destinations primarly forwarded to N, o if a router S has a set of X destinations primarly forwarded to N,
using per prefix LFA may lead to have a subset of X protected by a using per prefix LFA may lead to have a subset of X protected by a
neighbor N1, another subset by N2, another subset by Nx ... neighbor N1, another subset by N2, another subset by Nx ...
o S is not aware about traffic flows to each destination and is not o S is not aware about traffic flows to each destination and is not
able to evaluate how much traffic will be sent to N1,N2, ... Nx in able to evaluate how much traffic will be sent to N1,N2, ... Nx
case of FRR activation. in case of FRR activation.
Based on this, it is not useful to gather available bandwidth on Based on this, it is not useful to gather available bandwidth on
alternate paths, as the router does not know how much bandwidth it alternate paths, as the router does not know how much bandwidth it
requires for protection. The proposed link speed approach provides a requires for protection. The proposed link speed approach provides a
good approximation with a small cost as information is easily good approximation with a small cost as information is easily
available. available.
The bandwidth criteria of the policy framework SHOULD work in two The bandwidth criteria of the policy framework SHOULD work in two
ways : ways :
o PRUNE : exclude a LFA if link speed to reach it is lower than the o PRUNE : exclude a LFA if link speed to reach it is lower than the
link speed of the primary nexthop interface. link speed of the primary nexthop interface.
o PREFER : prefer a LFA based on his bandwidth to reach it compared o PREFER : prefer a LFA based on his bandwidth to reach it compared
to the link speed of the primary nexthop interface. to the link speed of the primary nexthop interface.
3.2.5.5. Neighbor preference 5.2.9. Neighbor preference
Rather than tagging interface on each node (using link color) to Rather than tagging interface on each node (using link color) to
identify neighbor node type (as example), it would be helpful if identify neighbor node type (as example), it would be helpful if
routers could be identified in the IGP. This would permit a grouped routers could be identified in the IGP. This would permit a grouped
processing on multiple nodes. [I-D.psarkar-isis-node-admin-tag] processing on multiple nodes. As an implementation need to exclude
proposes a tagging mechanism for ISIS nodes that may help the node some specific neighbors (see Section 5.2.3), an implementation :
identification. As an implementation need to exclude some specific
neighbors (see Section 3.2.3), an implementation :
o SHOULD be able to give a preference to specific neighbor. o SHOULD be able to give a preference to specific neighbor.
o SHOULD be able to give a preference to a group of neighbor. o SHOULD be able to give a preference to a group of neighbor.
o SHOULD be able to exclude a group of neighbor. o SHOULD be able to exclude a group of neighbor.
A specific neighbor may be identified by its interface or IP address A specific neighbor may be identified by its interface, IP address or
and group of neighbors may be identified by a marker like SUB-TLV1 in router ID and group of neighbors may be identified by a marker (tag).
TLV135. As multiple prefixes may be present in TLVs 135, an
heuristic is required to choose the appropriate one that will
identify the neighbor and will transport the tag associated with the
neighbor preference.
We propose the following algorithm to select the prefix :
1. Select the prefix in TLV#135 that is equal to TLV#134 value
(Router ID) and prefix length is 32.
2. Select the prefix in TLV#135 that is equal to TLV#132 value (IP
Addresses) and prefix length is 32, it must be noted that TLV#132
may transport multiple addresses and so multiple matches may
happen.
3. If multiple prefixes are matching TLV#132 values, choose the
highest one.
Consider the following network: Consider the following network:
PE3 PE3
| |
| |
PE2 PE2
| +---- P4 | +---- P4
| / | /
PE1 ---- P1 -------- P2 PE1 ---- P1 -------- P2
skipping to change at page 16, line 37 skipping to change at page 18, line 21
o P1,P2,P3: 50 (core). o P1,P2,P3: 50 (core).
A simple policy could be configured on P1 to choose the best A simple policy could be configured on P1 to choose the best
alternate for P1->P4 based on router function/role as follows : alternate for P1->P4 based on router function/role as follows :
o criteria 1 -> neighbor preference: exclude tag 100 and 200. o criteria 1 -> neighbor preference: exclude tag 100 and 200.
o criteria 2 -> bandwidth. o criteria 2 -> bandwidth.
4. Operational aspects 6. Operational aspects
4.1. ISIS overload bit on LFA computing node 6.1. ISIS overload bit on LFA computing node
In [RFC5286], Section 3.5, the setting of the overload bit condition In [RFC5286], Section 3.5, the setting of the overload bit condition
in LFA computation is only taken into account for the case where a in LFA computation is only taken into account for the case where a
neighbor has the overload bit set. neighbor has the overload bit set.
In addition to RFC 5286 inequality 1 Loop-Free Criterion In addition to RFC 5286 inequality 1 Loop-Free Criterion
(Distance_opt(N, D) < Distance_opt(N, S) + Distance_opt(S, D)), the (Distance_opt(N, D) < Distance_opt(N, S) + Distance_opt(S, D)), the
IS-IS overload bit of the LFA calculating neighbor (S) SHOULD be IS-IS overload bit of the LFA calculating neighbor (S) SHOULD be
taken into account. Indeed, if it has the overload bit set, no taken into account. Indeed, if it has the overload bit set, no
neighbor will loop back to traffic to itself. neighbor will loop back to traffic to itself.
4.2. Manual triggering of FRR 6.2. Manual triggering of FRR
Service providers often perform manual link shutdown (using router Service providers often perform manual link shutdown (using router
CLI) to perform some network changes/tests. Especially testing or CLI) to perform some network changes/tests. A manual link shutdown
may be done at multiple level : physical interface, logical
interface, IGP interface, BFD session ... Especially testing or
troubleshooting FRR requires to perform the manual shutdown on the troubleshooting FRR requires to perform the manual shutdown on the
remote end of the link as generally a local shutdown would not remote end of the link as generally a local shutdown would not
trigger FRR. To enhance such situation, an implementation SHOULD trigger FRR.
support triggering/activating LFA Fast Reroute for a given link when
a manual shutdown is done.
4.3. Required local information To enhance such situation, an implementation SHOULD support
triggering/activating LFA Fast Reroute for a given link when a manual
shutdown is done on a component that currently supports FRR
activation.
For example :
o if an implementation supports FRR activation upon BFD session down
event, this implementation SHOULD support FRR activation when a
manual shutdown is done on the BFD session. But if an
implementation does not support FRR activation on BFD session
down, there is no need for this implementation to support FRR
activation on manual shutdown of BFD session.
o if an implementation supports FRR activation on physical link down
event (e.g. Rx laser Off detection, or error threshold raised
...), this implementation SHOULD support FRR activation when a
manual shutdown at physical interface is done. But if an
implementation does not support FRR activation on physical link
down event, there is no need for this implementation to support
FRR activation on manual physical link shutdown.
6.3. Required local information
LFA introduction requires some enhancement in standard routing LFA introduction requires some enhancement in standard routing
information provided by implementations. Moreover, due to the non information provided by implementations. Moreover, due to the non
100% coverage, coverage informations is also required. 100% coverage, coverage informations is also required.
Hence an implementation : Hence an implementation :
o MUST be able to display, for every prefixes, the primary nexthop o MUST be able to display, for every prefixes, the primary nexthop
as well as the alternate nexthop information. as well as the alternate nexthop information.
skipping to change at page 17, line 47 skipping to change at page 20, line 5
prefixes per priority if implementation supports prefix-priority prefixes per priority if implementation supports prefix-priority
insertion in RIB/FIB. insertion in RIB/FIB.
o SHOULD provide a reason for chosing an alternate (policy and o SHOULD provide a reason for chosing an alternate (policy and
criteria) and for excluding an alternate. criteria) and for excluding an alternate.
o SHOULD provide the list of non protected prefixes and the reason o SHOULD provide the list of non protected prefixes and the reason
why they are not protected (no protection required or no alternate why they are not protected (no protection required or no alternate
available). available).
4.4. Coverage monitoring 6.4. Coverage monitoring
It is pretty easy to evaluate the coverage of a network in a nominal It is pretty easy to evaluate the coverage of a network in a nominal
situation, but topology changes may change the coverage. In some situation, but topology changes may change the coverage. In some
situations, the network may no longer be able to provide the required situations, the network may no longer be able to provide the required
level of protection. Hence, it becomes very important for service level of protection. Hence, it becomes very important for service
providers to get alerted about changes of coverage. providers to get alerted about changes of coverage.
An implementation SHOULD : An implementation SHOULD :
o provide an alert system if total coverage (for a node) is below a o provide an alert system if total coverage (for a node) is below a
skipping to change at page 18, line 24 skipping to change at page 20, line 30
An implementation MAY : An implementation MAY :
o provide an alert system if a specific destination is not protected o provide an alert system if a specific destination is not protected
anymore or when protection comes back up for this destination anymore or when protection comes back up for this destination
Although the procedures for providing alerts are beyond the scope of Although the procedures for providing alerts are beyond the scope of
this document, we recommend that implementations consider standard this document, we recommend that implementations consider standard
and well used mechanisms like syslog or SNMP traps. and well used mechanisms like syslog or SNMP traps.
4.5. Deterministic and documents LFA selection behavior 6.5. LFA and network planning
The operator may choose to run simulations in order to ensure full The operator may choose to run simulations in order to ensure full
coverage of a certain type for the whole network or a given subset of coverage of a certain type for the whole network or a given subset of
the network. This is particularly likely if he operates the network the network. This is particularly likely if he operates the network
in the sense of the third backbone profiles described in [RFC6571], in the sense of the third backbone profiles described in [RFC6571],
that is, he seeks to design and engineer the network topology in a that is, he seeks to design and engineer the network topology in a
way that a certain coverage is always achieved. Obviously a complete way that a certain coverage is always achieved. Obviously a complete
and exact simulation of the IP FRR coverage can only be achieved, if and exact simulation of the IP FRR coverage can only be achieved, if
the behavior is deterministic and if the algorithm used is available the behavior is deterministic and if the algorithm used is available
to the simulation tool. Thus, an implementation SHOULD: to the simulation tool. Thus, an implementation SHOULD:
skipping to change at page 19, line 5 skipping to change at page 21, line 6
prefix. prefix.
o Document its behavior. The implementation SHOULD provide enough o Document its behavior. The implementation SHOULD provide enough
documentation of its behavior that allows an implementer of a documentation of its behavior that allows an implementer of a
simulation tool, to foresee the exact choice of the LFA simulation tool, to foresee the exact choice of the LFA
implementation for every prefix in a given topology. This SHOULD implementation for every prefix in a given topology. This SHOULD
take into account all possible policy configuration options. One take into account all possible policy configuration options. One
possible way to document this behavior is to disclose the possible way to document this behavior is to disclose the
algorithm used to choose alternates. algorithm used to choose alternates.
5. Security Considerations 7. Security Considerations
This document does not introduce any change in security consideration This document does not introduce any change in security consideration
compared to [RFC5286]. compared to [RFC5286].
6. Contributors 8. Contributors
Significant contributions were made by Pierre Francois, Hannes Significant contributions were made by Pierre Francois, Hannes
Gredler, Chris Bowers, Jeff Tantsura and Mustapha Aissaoui which the Gredler, Chris Bowers, Jeff Tantsura, Uma Chunduri and Mustapha
authors would like to acknowledge. Aissaoui which the authors would like to acknowledge.
7. Acknowledgements 9. Acknowledgements
8. IANA Considerations 10. IANA Considerations
This document has no action for IANA. This document has no action for IANA.
9. References 11. References
9.1. Normative References 11.1. 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.
[RFC4203] Kompella, K. and Y. Rekhter, "OSPF Extensions in Support [RFC4203] Kompella, K. and Y. Rekhter, "OSPF Extensions in Support
of Generalized Multi-Protocol Label Switching (GMPLS)", of Generalized Multi-Protocol Label Switching (GMPLS)",
RFC 4203, October 2005. RFC 4203, October 2005.
[RFC4205] Kompella, K. and Y. Rekhter, "Intermediate System to [RFC4205] Kompella, K. and Y. Rekhter, "Intermediate System to
Intermediate System (IS-IS) Extensions in Support of Intermediate System (IS-IS) Extensions in Support of
Generalized Multi-Protocol Label Switching (GMPLS)", RFC Generalized Multi-Protocol Label Switching (GMPLS)",
4205, October 2005. RFC 4205, October 2005.
[RFC5286] Atlas, A. and A. Zinin, "Basic Specification for IP Fast [RFC5286] Atlas, A. and A. Zinin, "Basic Specification for IP Fast
Reroute: Loop-Free Alternates", RFC 5286, September 2008. Reroute: Loop-Free Alternates", RFC 5286, September 2008.
9.2. Informative References 11.2. Informative References
[I-D.ietf-rtgwg-remote-lfa] [I-D.ietf-rtgwg-remote-lfa]
Bryant, S., Filsfils, C., Previdi, S., Shand, M., and S. Bryant, S., Filsfils, C., Previdi, S., Shand, M., and S.
Ning, "Remote LFA FRR", draft-ietf-rtgwg-remote-lfa-04 Ning, "Remote LFA FRR", draft-ietf-rtgwg-remote-lfa-04
(work in progress), November 2013. (work in progress), November 2013.
[I-D.litkowski-rtgwg-lfa-rsvpte-cooperation] [I-D.litkowski-rtgwg-lfa-rsvpte-cooperation]
Litkowski, S., Decraene, B., Filsfils, C., and K. Raza, Litkowski, S., Decraene, B., Filsfils, C., and K. Raza,
"Interactions between LFA and RSVP-TE", draft-litkowski- "Interactions between LFA and RSVP-TE",
rtgwg-lfa-rsvpte-cooperation-02 (work in progress), August draft-litkowski-rtgwg-lfa-rsvpte-cooperation-02 (work in
2013. progress), August 2013.
[I-D.psarkar-isis-node-admin-tag] [I-D.psarkar-isis-node-admin-tag]
psarkar@juniper.net, p., Gredler, H., Hegde, S., psarkar@juniper.net, p., Gredler, H., Hegde, S.,
Raghuveer, H., Litkowski, S., and B. Decraene, Raghuveer, H., Litkowski, S., and B. Decraene,
"Advertising Per-node Admin Tags in IS-IS", draft-psarkar- "Advertising Per-node Admin Tags in IS-IS",
isis-node-admin-tag-00 (work in progress), October 2013. draft-psarkar-isis-node-admin-tag-00 (work in progress),
October 2013.
[I-D.psarkar-rtgwg-rlfa-node-protection] [I-D.psarkar-rtgwg-rlfa-node-protection]
psarkar@juniper.net, p., Gredler, H., Hegde, S., psarkar@juniper.net, p., Gredler, H., Hegde, S.,
Raghuveer, H., cbowers@juniper.net, c., and S. Litkowski, Raghuveer, H., cbowers@juniper.net, c., and S. Litkowski,
"Remote-LFA Node Protection and Manageability", draft- "Remote-LFA Node Protection and Manageability",
psarkar-rtgwg-rlfa-node-protection-03 (work in progress), draft-psarkar-rtgwg-rlfa-node-protection-03 (work in
December 2013. progress), December 2013.
[RFC3630] Katz, D., Kompella, K., and D. Yeung, "Traffic Engineering [RFC3630] Katz, D., Kompella, K., and D. Yeung, "Traffic Engineering
(TE) Extensions to OSPF Version 2", RFC 3630, September (TE) Extensions to OSPF Version 2", RFC 3630,
2003. September 2003.
[RFC3906] Shen, N. and H. Smit, "Calculating Interior Gateway [RFC3906] Shen, N. and H. Smit, "Calculating Interior Gateway
Protocol (IGP) Routes Over Traffic Engineering Tunnels", Protocol (IGP) Routes Over Traffic Engineering Tunnels",
RFC 3906, October 2004. RFC 3906, October 2004.
[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, May Extensions to RSVP-TE for LSP Tunnels", RFC 4090,
2005. May 2005.
[RFC5305] Li, T. and H. Smit, "IS-IS Extensions for Traffic [RFC5305] Li, T. and H. Smit, "IS-IS Extensions for Traffic
Engineering", RFC 5305, October 2008. Engineering", RFC 5305, October 2008.
[RFC5714] Shand, M. and S. Bryant, "IP Fast Reroute Framework", RFC [RFC5714] Shand, M. and S. Bryant, "IP Fast Reroute Framework",
5714, January 2010. RFC 5714, January 2010.
[RFC5715] Shand, M. and S. Bryant, "A Framework for Loop-Free [RFC5715] Shand, M. and S. Bryant, "A Framework for Loop-Free
Convergence", RFC 5715, January 2010. Convergence", RFC 5715, January 2010.
[RFC6571] Filsfils, C., Francois, P., Shand, M., Decraene, B., [RFC6571] Filsfils, C., Francois, P., Shand, M., Decraene, B.,
Uttaro, J., Leymann, N., and M. Horneffer, "Loop-Free Uttaro, J., Leymann, N., and M. Horneffer, "Loop-Free
Alternate (LFA) Applicability in Service Provider (SP) Alternate (LFA) Applicability in Service Provider (SP)
Networks", RFC 6571, June 2012. Networks", RFC 6571, June 2012.
Authors' Addresses Authors' Addresses
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