PCE Working Group H. Chen
Internet-Draft V. Kondreddy
Intended status: Informational D. Dhody
Expires: April 25, 2013 Huawei Technologies
October 22, 2012
The Applicability of the PCE to Computing Protection and Recovery Paths
for Single Domain and Multi-Domain Networks.
draft-chen-pce-protection-applicability-02
Abstract
The Path Computation Element (PCE) provides path computation
functions in support of traffic engineering in Multiprotocol Label
Switching (MPLS) and Generalized MPLS (GMPLS) networks.
A link or node failure can significantly impact network services in
large-scale networks. Therefore it is important to ensure the
survivability of large scale networks which consist of various
connections provided over multiple interconnected networks with
varying technologies.
This document examines the applicability of the PCE architecture,
protocols, and procedures for computing protection paths and
restoration services, for single and multi-domain networks.
This document also explains the mechanism of Fast Re-Route (FRR)
where a point of local repair (PLR) needs to find the appropriate
merge point (MP) to do bypass path computation using PCE.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
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Internet-Drafts are draft documents valid for a maximum of six months
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on April 25, 2013.
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Copyright Notice
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1. Domains . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1.1. Inter-domain LSPs . . . . . . . . . . . . . . . . . . 5
1.2. Recovery . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.3. Requirements Language . . . . . . . . . . . . . . . . . . 5
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5
3. Path Computation Element Architecture Considerations . . . . . 7
3.1. Online Path Computation . . . . . . . . . . . . . . . . . 7
3.2. Offline Path Computation . . . . . . . . . . . . . . . . . 7
4. Protection Service Traffic Engineering . . . . . . . . . . . . 8
4.1. Path Computation . . . . . . . . . . . . . . . . . . . . . 8
4.2. Bandwidth Reservation . . . . . . . . . . . . . . . . . . 8
4.3. Disjoint Path . . . . . . . . . . . . . . . . . . . . . . 8
4.4. Service Preemption . . . . . . . . . . . . . . . . . . . . 8
4.5. Share Risk Link Groups . . . . . . . . . . . . . . . . . . 8
4.6. Multi-Homing . . . . . . . . . . . . . . . . . . . . . . . 8
4.6.1. Ingress and Egress Protection . . . . . . . . . . . . 9
5. Packet Protection Applications . . . . . . . . . . . . . . . . 9
5.1. Single Domain Service Protection . . . . . . . . . . . . . 10
5.2. Multi-domain Service Protection . . . . . . . . . . . . . 10
5.3. Backup Path Computation . . . . . . . . . . . . . . . . . 10
5.4. Fast Reroute (FRR) Path Computation . . . . . . . . . . . 10
5.4.1. Methods to find MP and calculate the optimal
backup path . . . . . . . . . . . . . . . . . . . . . 11
5.4.1.1. Intra-domain node protection . . . . . . . . . . . 12
5.4.1.2. Boundary node protection . . . . . . . . . . . . . 12
5.5. Point-to-Multipoint Path Protection . . . . . . . . . . . 15
6. Optical Protection Applications . . . . . . . . . . . . . . . 16
6.1. ASON Applicability . . . . . . . . . . . . . . . . . . . . 16
6.2. Multi-domain Restoration . . . . . . . . . . . . . . . . . 16
7. Path and Service Protection Gaps . . . . . . . . . . . . . . . 16
8. Manageability Considerations . . . . . . . . . . . . . . . . . 16
8.1. Control of Function and Policy . . . . . . . . . . . . . . 16
8.2. Information and Data Models . . . . . . . . . . . . . . . 16
8.3. Liveness Detection and Monitoring . . . . . . . . . . . . 16
8.4. Verify Correct Operations . . . . . . . . . . . . . . . . 16
8.5. Requirements On Other Protocols . . . . . . . . . . . . . 16
8.6. Impact On Network Operations . . . . . . . . . . . . . . . 16
9. Security Considerations . . . . . . . . . . . . . . . . . . . 16
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 16
11. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 17
12. References . . . . . . . . . . . . . . . . . . . . . . . . . . 17
12.1. Normative References . . . . . . . . . . . . . . . . . . . 17
12.2. Informative References . . . . . . . . . . . . . . . . . . 17
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1. Introduction
Network survivability remains a major concern for network operators
and service providers, particularly as expanding applications such as
private and Public Cloud drive increasingly more traffic across
longer ranges, to a wider number of users. A variety of well-known
pre-planned protection and post-fault recovery schemes have been
developed for IP, MPLS and GMPLS networks.
The Path Computation Element (PCE) [RFC4655] can be used to perform
complex path computation in large single domain, multi-domain and
multi-layered networks. The PCE can also be used to compute a
variety of restoration and protection paths and services.
This document examines the applicability of the PCE architecture,
protocols, and protocol extensions for computing protection paths and
restoration services.
1.1. Domains
A domain can be defined as a separate administrative, geographic, or
switching environment within the network. A domain may be further
defined as a zone of routing or computational ability. Under these
definitions a domain might be categorized as an Antonymous System
(AS) or an Interior Gateway Protocol (IGP) area (as per [RFC4726] and
[RFC4655]), or specific switching environment.
In the context of GMPLS, a particularly important example of a domain
is the Automatically Switched Optical Network (ASON) subnetwork
[G-8080]. In this case, computation of an end-to-end path requires
the selection of nodes and links within a parent domain where some
nodes may, in fact, be subnetworks. Furthermore, a domain might be
an ASON routing area [G-7715]. A PCE may perform the path
computation function of an ASON routing controller as described in
[G-7715-2].
It is assumed that the PCE architecture should be applied to small
inter-domain topologies and not to solve route computation issues
across large groups of domains, I.E. the entire Internet.
Most existing protocol mechanisms for network survivability have
focused on single-domain scenarios. Multi-domain scenarios are much
more complex and challenging as domain topology information is
typically not shared outside each specific domain.
Therefore multi-domain survivability is a key requirement for today's
complex networks. It is important to develop more adaptive multi-
domain recovery solutions for various failure scenarios.
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1.1.1. Inter-domain LSPs
Three signaling options are defined for setting up an inter-area or
inter-AS LSP [RFC4726]:
o Contiguous LSP
o Stitched LSP
o Nested LSP
1.2. Recovery
Typically traffic-engineered networks such as MPLS-TE and GMPLS, use
protection and recovery mechanisms based on the pre-established use
of a packet or optical LSP and/or the availability of spare resources
and the network topology.
1.3. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
In this document, these words will appear with that interpretation
only when in ALL CAPS. Lower case uses of these words are not to be
interpreted as carrying [RFC2119] significance.
2. Terminology
The following terminology is used in this document.
ABR: Area Border Router. Router used to connect two IGP areas
(Areas in OSPF or levels in IS-IS).
ASBR: Autonomous System Border Router. Router used to connect
together ASes of the same or different service providers via one
or more inter-AS links.
BN: Boundary Node (BN). A boundary node is either an ABR in the
context of inter-area Traffic Engineering or an ASBR in the
context of inter-AS Traffic Engineering.
CPS: Confidential Path Segment. A segment of a path that contains
nodes and links that the AS policy requires not to be disclosed
outside the AS.
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CSP: Communication Service Provide.
CSPF: Constrained Shorted Path First Algorithm.
ERO: Explicit Route Object.
FRR: Fast Re-Route.
IGP: Interior Gateway Protocol. Either of the two routing
protocols, Open Shortest Path First (OSPF) or Intermediate System
to Intermediate System (IS-IS).
Inter-area TE LSP: A TE LSP whose path transits through two or more
IGP areas.
Inter-AS TE LSP: A TE LSP whose path transits through two or more
ASs or sub-ASs (BGP confederations).
IS-IS: Intermediate System to Intermediate System.
LSP: Label Switched Path.
LSR: Label Switching Router.
MP: Merge Point. The LSR where one or more backup tunnels rejoin
the path of the protected LSP downstream of the potential failure.
OSPF: Open Shortest Path First.
PCC: Path Computation Client. Any client application requesting a
path computation to be performed by a Path Computation Element.
PCE: Path Computation Element. An entity (component, application,
or network node) that is capable of computing a network path or
route based on a network graph and applying computational
constraints.
PKS: Path Key Subobject. A subobject of an Explicit Route Object or
Record Route Object that encodes a CPS so as to preserve
confidentiality.
PLR: Point of Local Repair. The head-end LSR of a backup tunnel or
a detour LSP.
RRO: Record Route Object.
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RSVP: Resource Reservation Protocol.
SRLG: Shared Risk Link Group.
TE: Traffic Engineering.
TED: Traffic Engineering Database, which contains the topology and
resource information of the domain. The TED may be fed by
Interior Gateway Protocol (IGP) extensions or potentially by other
means.
This document also uses the terminology defined in [RFC4655] and
[RFC5440].
3. Path Computation Element Architecture Considerations
For the purpose of this document it is assumed that the path
computation is the sole responsibility of the PCE as per the
architecture defined in [RFC4655]. When a path is required the Path
Computation Client (PCC) will send a request to the PCE. The PCE
will apply the required constraints and compute a path and return a
response to the PCC. In the context of this document it may be
necessary for the PCE to co-operate with other PCEs in adjacent
domains (as per BRPC [RFC5441]) or cooperate with the Parent PCE (as
per [PCE-HIERARCHY-FWK]).
A PCE may be used to compute end-to-end paths across single or
multiple domains. Multiple PCEs may be dedicated to each area to
provide sufficient path computation capacity and redundancy for each
domain.
During path computation [RFC5440], a PCC request may contain backup
LSP requirements in order to setup in the same time the primary and
backup LSPs. This request is known as dependent path computations.
A typical dependent request for a primary and backup service would
request that the computation assign a set of diverse paths, so both
services are disjointed from each other.
3.1. Online Path Computation
Online path computation is performed on-demand as nodes in the
network determine that they need to know the paths to use for
services.
3.2. Offline Path Computation
Offline path computation is performed ahead of time, before the LSP
setup is requested. That means that it is requested by, or performed
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as part of, a management application.
This method of computation allows the optimal placement of services
and explicit control of services. A Communication Service Provide
(CSP) can plan where new protection services will be placed ahead of
time. Furthermore by computing paths offline specific scenarios can
be considered and a global view of network resources is available.
Finally, offline path computation provides a method to compute
protection paths in the event of a single, or multiple, link
failures. This allows the placement of backup services in the event
of catastrophic network failures.
4. Protection Service Traffic Engineering
4.1. Path Computation
This document describes how the PCE architecture defined in [RFC4655]
may be utilized to compute protection and recovery paths for critical
network services. In the context of this document (inter-domain) it
may be necessary for the PCE to co-operate with other PCEs in
adjacent domains (as per BRPC [RFC5441]) or cooperate with the Parent
PCE (as per [PCE-HIERARCHY-FWK]).
4.2. Bandwidth Reservation
4.3. Disjoint Path
Disjoint paths are required for end-to-end protection services. A
backup service may be required to be fully disjoint from the primary
service, link disjoint (allowing common nodes on the paths), or best-
effort disjoint (allowing shared links or nodes when no other path
can be found).
4.4. Service Preemption
4.5. Share Risk Link Groups
4.6. Multi-Homing
Networks constructed from multi-areas or multi-AS environments may
have multiple interconnect points (multi-homing). End-to-end path
computations may need to use different interconnect points to avoid
single point failures disrupting primary and backup services.
Domain and path diversity may also be required when computing end-to-
end paths. Domain diversity should facilitate the selection of paths
that share ingress and egress domains, but do not share transit
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domains. Therefore, there must be a method allowing the inclusion or
exclusion of specific domains when computing end-to-end paths.
4.6.1. Ingress and Egress Protection
An end-to-end primary service carried by a primary TE LSP from a
primary ingress node to a primary egress node may need to be
protected against the failures in the ingress and the egress. In
this case, a backup ingress and a backup egress are required, which
are different from the primary ingress and the primary egress
respectively. The backup ingress should be in the same domain as the
primary ingress, and the backup egress should be in the same domain
as the primary egress.
A source of the service traffic may be sent to both the primary
ingress and the backup ingress (dual-homing). The source may not be
in the same domain as the primary ingress and the backup ingress.
When the primary ingress fails, the service traffic is delivered
through the backup ingress.
A receiver of the service traffic may be connected to both the
primary egress and the backup egress (dual-homing). The receiver may
not be in the same domain as the primary egress and the backup
egress. When the primary egress fails, the receiver gets the service
traffic from the backup egress.
5. Packet Protection Applications
Network survivability is a key objective for CSPs, particularly as
expanding revenue services (cloud and data center applications) are
increasing exponentially.
Pre-fault paths are pre-computed and protection resources are
reserved a priory for rapid recovery. In the event of a network
failure on the primary path, the traffic is fast switched to the
backup path. These pre-provisioned mechanisms are capable of
ensuring protection against single link failures.
Post-fault restoration schemes are reactive and require a reactive
routing procedure to set up new working paths in the event of a
failure. Post fault restoration can significantly impact network
services as they are typically impacted by longer restoration delays
and cannot guarantee recovery of a service. However, they are much
more network resource efficient and are capable of handling multi-
failure situations.
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5.1. Single Domain Service Protection
A variety of pre-planned protection and post-fault restoration
recovery schemes are available for single domain MPLS and GMPLS
networks, these include:
o Path Recovery
o Path Segment Recovery
o Local Recovery (Fast Reroute)
5.2. Multi-domain Service Protection
Typically network survivability has focused on single-domain
scenarios. By contrast, broader multi-domain scenarios are much more
challenging as no single entity has a global view of topology
information. As a result, multi-domain survivability is very
important.
A PCE may be used to compute end-to-end paths across multi-domain
environments using a per-domain path computation technique [RFC5152].
The so called backward recursive path computation (BRPC) mechanism
[RFC5441] defines a PCE-based path computation procedure to compute
inter-domain constrained LSPs.
5.3. Backup Path Computation
A PCE can be used to compute backup paths in the context of fast
reroute protection of TE LSPs. In this model, all backup TE LSPs
protecting a given facility are computed in a coordinated manner by a
PCE. This allows complete bandwidth sharing between backup tunnels
protecting independent elements, while avoiding any extensions to TE
LSP signaling. Both centralized and distributed computation models
are applicable. In the distributed case each LSR can be a PCE to
compute the paths of backup tunnels to protect against the failure of
adjacent network links or nodes.
5.4. Fast Reroute (FRR) Path Computation
As stated in [RFC4090], there are two independent methods (one-to-one
backup and facility backup) of doing fast reroute (FRR). PCE can be
used to compute backup path for both of the methods. Cooperating
PCEs may be used to compute inter-domain backup path.
In case of one to one backup method, the destination MUST be the
tail-end of the protected LSP. Whereas for facility backup,
destination MUST be the address of the merge point (MP) from the
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corresponding point of local repair (PLR). The problem of finding
the MP using the interface addresses or node-ids present in Record
Route Object (RRO) of protected path can be easily solved in the case
of a single Interior Gateway Protocol (IGP) area because the PLR has
the complete Traffic Engineering Database (TED). Thus, the PLR can
unambiguously determine -
o The MP address regardless of RRO IPv4 or IPv6 sub-objects
(interface address or LSR ID).
o Does a backup tunnel intersecting a protected TE LSP on MP node
exist? This is the case where facility backup tunnel already
exists either due to another protected TE LSP or it is pre-
configured.
It is complex for a PLR to find the MP in case of boundary node
protection for computing a bypass path because the PLR doesn't have
the full TED visibility. When confidentiality (via path key)
[RFC5520] is enabled, finding MP is very complex.
This document describes the mechanism to find MP and to setup bypass
tunnel to protect a boundary node.
5.4.1. Methods to find MP and calculate the optimal backup path
The Merge Point (MP) address is required at the PLR in order to
select a bypass tunnel intersecting a protected Traffic Engineering
Label Switched Path (TE LSP) on a downstream LSR.
Some implementations may choose to pre-configure a bypass tunnel on
PLR with destination address as MP. MP's Domain to be traversed by
bypass path can be administratively configured or learned via some
other means (ex Hierarchical PCE (HPCE) [PCE-HIERARCHY-FWK]). Path
Computation Client (PCC) on PLR can request its local PCE to compute
bypass path from PLR to MP, excluding links and node between PLR and
MP. At PLR once primary tunnel is up, a pre-configured bypass tunnel
is bound to the primary tunnel, note that multiple bypass tunnels can
also exist.
Most implementations may choose to create a bypass tunnel on PLR
after primary tunnel is signaled with Record Route Object (RRO) being
present in primary path's Resource Reservation Protocol (RSVP) Path
Reserve message. MP address has to be determined (described below)
to create a bypass tunnel. PCC on PLR can request its local PCE to
compute bypass path from PLR to MP, excluding links and node between
PLR and MP.
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5.4.1.1. Intra-domain node protection
[R1]----[R2]----[R3]----[R4]---[R5]
\ /
[R6]--[R7]--[R8]
Protected LSP Path: [R1->R2->R3->R4->R5]
Bypass LSP Path: [R2->R6->R7->R8->R4]
Figure 1: Node Protection for R3
In Figure 1, R2 has to build a bypass tunnel that protects against
the failure of link [R2->R3] and node [R3]. R2 is PLR and R4 is MP
in this case. Since, both PLR and MP belong to the same area. The
problem of finding the MP using the interface addresses or node-ids
can be easily solved. Thus, the PLR can unambiguously find the MP
address regardless of RRO IPv4 or IPv6 sub-objects (interface address
or LSR ID) and also determine whether a backup tunnel intersecting a
protected TE LSP on a downstream node (MP) already exists.
TED on PLR will have the information of both R2 and R4, which can be
used to find MP's TE router IP address and compute optimal backup
path from R2 to R4, excluding link [R2->R3] and node [R3].
Thus, RSVP-TE can signal bypass tunnel along the computed path.
5.4.1.2. Boundary node protection
5.4.1.2.1. Area Boundary Router (ABR) node protection
|
PCE-1 | PCE-2
|
IGP area 0 | IGP area 1
|
|
[R1]----[R2]----[R3]----[R4]---[R5]
\ | /
[R6]--[R7]--[R8]
|
|
|
Protected LSP Path: [R1->R2->R3->R4->R5]
Bypass LSP Path: [R2->R6->R7->R8->R4]
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Figure 2: Node Protection for R3 (ABR)
In Figure 2, cooperating PCE(s) (PCE-1 and PCE-2) have computed the
primary LSP Path [R1->R2->R3->R4->R5] and provided to R1 (PCC).
R2 has to build a bypass tunnel that protects against the failure of
link [R2->R3] and node [R3]. R2 is PLR and R4 is MP. Both PLR and
MP are in different area. TED on PLR doesn't have the information of
R4.
The problem of finding the MP address in a network with inter-domain
TE LSP is solved by inserting a node-id sub-object [RFC4561] in the
RRO object carried in the RSVP Path Reserve message. PLR can find
out the MP from the RRO it has received in Path Reserve message from
its downstream LSR.
But the computation of optimal backup path from R2 to R4, excluding
link [R2->R3] and node [R3] is not possible with running of
Constrained Shortest Path First (CSPF) algorithm locally at R2. PCE
can be used to compute backup path in this case. R2 acting as PCC on
PLR can request PCE-1 to compute bypass path from PLR(R2) to MP(R4),
excluding link [R2->R3] and node [R3]. PCE MAY use inter-domain path
computation mechanism (like HPCE ([PCE-HIERARCHY-FWK]) etc) when the
domain information of MP is unknown at PLR. Further, RSVP-TE can
signal bypass tunnel along the computed path.
5.4.1.2.2. Autonomous System Border Router (ASBR) node protection
| |
PCE-1 | | PCE-2
| |
AS 100 | | AS 200
| |
| |
[R1]----[R2]-------[R3]---------[R4]---[R5]
|\ | /
| +-----[R6]--[R7]--[R8]
| |
| |
Protected LSP Path: [R1->R2->R3->R4->R5]
Bypass LSP Path: [R2->R6->R7->R8->R4]
Figure 3: Node Protection for R3 (ASBR)
In Figure 3, Links [R2->R3] and [R2->R6] are inter-AS links. IGP
extensions ([RFC5316] and [RFC5392]) describe the flooding of
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inter-AS TE information for inter-AS path computation. Cooperating
PCE(s) (PCE-1 and PCE-2) have computed the primary LSP Path
[R1->R2->R3->R4->R5] and provided to R1 (PCC).
R2 is PLR and R4 is MP. Both PLR and MP are in different AS. TED on
PLR doesn't have the information of R4.
The address of MP can be found using node-id sub-object [RFC4561] in
the RRO object carried in the RSVP Path Reserve message. And
Cooperating PCEs could be used to compute the inter-AS bypass path.
Thus ASBR boundary node protection is similar to ABR protection.
5.4.1.2.3. Boundary node protection with Path-Key Confidentiality
[RFC5520] defines a mechanism to hide the contents of a segment of a
path, called the Confidential Path Segment (CPS). The CPS may be
replaced by a path-key that can be conveyed in the PCE Communication
Protocol (PCEP) and signaled within in a Resource Reservation
Protocol TE (RSVP-TE) explicit route object.
[RFC5553] states that, when the signaling message crosses a domain
boundary, the path segment that needs to be hidden (that is, a CPS)
MAY be replaced in the RRO with a PKS. Note that RRO in Resv message
carries the same PKS as originally signaled in the ERO of the Path
message.
5.4.1.2.3.1. Area Boundary Router (ABR) node protection
|
PCE-1 | PCE-2
|
IGP area 0 | IGP area 1
|
|
[R1]----[R2]----[R3]----[R4]---[R5]---[R9]
\ | /
[R6]--[R7]--[R8]
|
|
|
Figure 4: Node Protection for R3 (ABR) and Path-Key
In Figure 4, when path-key is enabled, cooperating PCE(s) (PCE-1 and
PCE-2) have computed the primary LSP Path [R1->R2->R3->PKS->R9] and
provided to R1 (PCC).
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When the ABR node (R3) replaces the CPS with PKS (as originally
signaled) during the Reserve message handling, it MAY also add the
immediate downstream node-id (R4) (so that the PLR (R2) can identify
the MP (R4)). Further the PLR (R2) SHOULD remove the MP node-id (R4)
before sending the Reserve message upstream to head end router.
Once MP is identified, the backup path computation using PCE is as
described earlier. (Section 5.4.1.2.1)
5.4.1.2.3.2. Autonomous System Border Router (ASBR) node protection
| |
PCE-1 | | PCE-2
| |
AS 100 | | AS 200
| |
| |
[R1]----[R2]-------[R3]---------[R4]---[R5]
|\ | /
| +-----[R6]--[R7]--[R8]
| |
| |
Figure 5: Node Protection for R3 (ASBR)
The address of MP can be found using the same mechanism as explained
above. Thus ASBR boundary node protection is similar to ABR
protection.
5.5. Point-to-Multipoint Path Protection
A PCE utilizing the extensions outlined in [RFC6006] (Extensions to
PCEP for Point-to-Multipoint Traffic Engineering Label Switched
Paths), can be used to compute point-to-multipoint (P2MP) paths. A
PCC requesting path computation for a primary and backup path can
request that these dependent computations use diverse paths.
Furthermore, the specification also defines two new options for P2MP
path dependent computation requests. The first option allows the PCC
to request that the PCE should compute a secondary P2MP path tree
with partial path diversity for specific leaves or a specific source-
to-leaf (sub-path to the primary P2MP path tree. The second option,
allows the PCC to request that partial paths should be link direction
diverse.
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6. Optical Protection Applications
6.1. ASON Applicability
6.2. Multi-domain Restoration
7. Path and Service Protection Gaps
8. Manageability Considerations
8.1. Control of Function and Policy
TBD
8.2. Information and Data Models
TBD
8.3. Liveness Detection and Monitoring
TBD
8.4. Verify Correct Operations
TBD
8.5. Requirements On Other Protocols
TBD
8.6. Impact On Network Operations
TBD
9. Security Considerations
This document does not introduce new security issues. However, MP's
node-id is carried as subobject in RRO across domain. This
relaxation is required to find MP in case of BN protection. The
security considerations pertaining to the [RFC3209], [RFC4090] and
[RFC5440] protocols remain relevant.
10. IANA Considerations
This document makes no requests for IANA action.
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11. Acknowledgement
We would like to thank Daniel King, Udayashree Palle, Sandeep Boina &
Reeja Paul for their useful comments and suggestions.
12. References
12.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to
Indicate Requirement Levels", BCP 14, RFC 2119,
March 1997.
12.2. Informative References
[RFC3209] Awduche, D., Berger, L., Gan, D., Li, T.,
Srinivasan, V., and G. Swallow, "RSVP-TE:
Extensions to RSVP for LSP Tunnels", RFC 3209,
December 2001.
[RFC4090] Pan, P., Swallow, G., and A. Atlas, "Fast
Reroute Extensions to RSVP-TE for LSP Tunnels",
RFC 4090, May 2005.
[RFC4561] Vasseur, J., Ali, Z., and S. Sivabalan,
"Definition of a Record Route Object (RRO)
Node-Id Sub-Object", RFC 4561, June 2006.
[RFC4655] Farrel, A., Vasseur, J., and J. Ash, "A Path
Computation Element (PCE)-Based Architecture",
RFC 4655, August 2006.
[RFC4726] Farrel, A., Vasseur, J., and A. Ayyangar, "A
Framework for Inter-Domain Multiprotocol Label
Switching Traffic Engineering", RFC 4726,
November 2006.
[RFC5152] Vasseur, JP., Ayyangar, A., and R. Zhang, "A
Per-Domain Path Computation Method for
Establishing Inter-Domain Traffic Engineering
(TE) Label Switched Paths (LSPs)", RFC 5152,
February 2008.
[RFC5316] Chen, M., Zhang, R., and X. Duan, "ISIS
Extensions in Support of Inter-Autonomous System
(AS) MPLS and GMPLS Traffic Engineering",
RFC 5316, December 2008.
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[RFC5392] Chen, M., Zhang, R., and X. Duan, "OSPF
Extensions in Support of Inter-Autonomous System
(AS) MPLS and GMPLS Traffic Engineering",
RFC 5392, January 2009.
[RFC5440] Vasseur, JP. and JL. Le Roux, "Path Computation
Element (PCE) Communication Protocol (PCEP)",
RFC 5440, March 2009.
[RFC5441] Vasseur, JP., Zhang, R., Bitar, N., and JL. Le
Roux, "A Backward-Recursive PCE-Based
Computation (BRPC) Procedure to Compute Shortest
Constrained Inter-Domain Traffic Engineering
Label Switched Paths", RFC 5441, April 2009.
[RFC5520] Bradford, R., Vasseur, JP., and A. Farrel,
"Preserving Topology Confidentiality in Inter-
Domain Path Computation Using a Path-Key-Based
Mechanism", RFC 5520, April 2009.
[RFC5553] Farrel, A., Bradford, R., and JP. Vasseur,
"Resource Reservation Protocol (RSVP) Extensions
for Path Key Support", RFC 5553, May 2009.
[RFC6006] Zhao, Q., King, D., Verhaeghe, F., Takeda, T.,
Ali, Z., and J. Meuric, "Extensions to the Path
Computation Element Communication Protocol
(PCEP) for Point-to-Multipoint Traffic
Engineering Label Switched Paths", RFC 6006,
September 2010.
[PCE-HIERARCHY-FWK] King, D. and A. Farrel, "The Application of the
Path Computation Element Architecture to the
Determination of a Sequence of Domains in MPLS
and GMPLS. (draft-ietf-pce-hierarchy-fwk-05)",
August 2012.
[G-7715] ITU-T, "ITU-T Recommendation G.7715 (2002),
Architecture and Requirements for the
Automatically Switched Optical Network (ASON).".
[G-7715-2] ITU-T, "ITU-T Recommendation G.7715.2 (2007),
ASON routing architecture and requirements for
remote route query.".
[G-8080] ITU-T, "ITU-T Recommendation G.8080/Y.1304,
Architecture for the automatically switched
optical network (ASON).".
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Authors' Addresses
Huaimo Chen
Huawei Technologies
Boston, MA
USA
EMail: huaimo.chen@huawei.com
Venugopal Reddy Kondreddy
Huawei Technologies
Leela Palace
Bangalore, Karnataka 560008
INDIA
EMail: venugopalreddyk@huawei.com
Dhruv Dhody
Huawei Technologies
Leela Palace
Bangalore, Karnataka 560008
INDIA
EMail: dhruv.dhody@huawei.com
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