One document matched: draft-lee-pce-ted-alternatives-02.txt
Differences from draft-lee-pce-ted-alternatives-01.txt
PCE Y. Lee (Ed.)
Internet Draft Huawei
G. Bernstein (Ed.)
Grotto Networking
Intended status: Informational May 5, 2009
Expires: November 2009
Alternative Approaches to Traffic Engineering Database Creation and
Maintenance for Path Computation Elements
draft-lee-pce-ted-alternatives-02.txt
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Copyright (c) 2009 IETF Trust and the persons identified as the
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Abstract
In order to compute and provide optimal paths, Path Computation
Elements (PCEs) require an accurate and timely Traffic Engineering
Database (TED). Traditionally this TED has been obtained from a link
state routing protocol supporting traffic engineering extensions.
This document discusses possible alternatives and enhancements to the
existing approach to TED creation. This document gives architectural
alternatives for these enhancements and their potential impacts on
network nodes, routing protocols, and PCEs.
Table of Contents
1. Introduction...................................................2
1.1. TED Creation and Maintenance via IGP-TEs..................4
2. Alternative TED Creation & Maintenance for a PCE...............5
2.1. Architecture Options......................................7
2.1.1. Nodes Send TE Info to all PCEs......................11
2.1.2. Nodes Send TE Info via an Intermediate System.......11
2.1.3. Nodes Send TE Info to At Least One PCE..............11
2.2. Nodes Finding PCEs.......................................12
2.3. Node TE Information Update Procedures....................13
2.4. PCE TED Maintenance Procedures...........................13
3. Standardization and Protocol Considerations...................13
3.1. Architecture Specific Standardization Aspects............15
4. Security Considerations.......................................15
5. IANA Considerations...........................................15
6. Conclusions...................................................16
7. Acknowledgments...............................................16
8. References....................................................16
8.1. Normative References.....................................16
8.2. Informative References...................................17
Author's Addresses...............................................18
Intellectual Property Statement..................................19
Disclaimer of Validity...........................................19
1. Introduction
In Multiprotocol Label Switching (MPLS) and Generalized MPLS (GMPLS),
a Traffic Engineering Database (TED) is used in computing paths for
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connection oriented packet services and for circuits. The TED
contains all relevant information that a Path Computation Element
(PCE) needs to perform its computations. It is important that the TED
be complete and accurate each time the PCE performs a path
computation.
In MPLS and GMPLS, interior gateway routing protocols (IGPs) have
been used to create and maintain a copy of the TED at each node
running the IGP. One of the benefits of the PCE architecture
[RFC4655] is the use of computationally more sophisticated path
computation algorithms and the realization that these may need
enhanced processing power not necessarily available at each node
participating in an IGP.
Section 4.3 [RFC4655] describes the potential load of the TED on a
network node and proposes an architecture where the TED is maintained
by the PCE rather than the network nodes. What isn't discussed is how
a PCE would obtain the information needed to populate its TED. In
this document we propose approaches for creating and maintaining the
TED on a PCE and look at the impacts from the PCE, IGP, and node
perspective.
New application areas for GMPLS and PCE include Wavelength Switched
Optical Networking (WSON). WSON scenarios can be divided into routing
wavelength assignment (RWA) problems where no consideration is made
of optical impairments, and optical impairment-aware deployments.
Even in the non-impairment case WSON requires detailed information
about switching node asymmetries and wavelength constraints as well
as detailed up to date information on wavelength usage per link
[WSON-Frame]. When combined with optical impairment data [WSON-IMP-
Info] even with the minimum set specified in [G.680], the total
amount of data to enable impairment aware RWA in WSON requires
significantly more information to be held in the TED than is required
for other traffic engineered networks. In addition, optical
impairment information may have sharing constraints [Imp-Frame] which
prevents some of this information from being distributed via an IGP-
TE but is still needed for the TED.
In some circumstances such additional information could "bog down"
the IGP on the nodes from a data processing, a storage, or
communications perspective. In environments where PCEs are external
to the nodes running the IGP, and where the information in the TED is
not used by the switching nodes it makes sense to investigate
alternative methods to create and maintain the TED at its place of
use, the PCE.
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This draft does not advocate that the alternative methods specified
in this draft should completely replace the IGP-TE as the method of
creating the TED. The split between the data to be distributed via an
IGP and the information conveyed via one of the alternatives in this
document depends on the nature of the network situation. One could
potentially choose to have some traffic engineering information
distributed via an IGP while other more specialized traffic
information is only conveyed to the PCEs via an alternative discussed
here. In addition, the methods specified in this draft is only
relevant to a set of architecture options where routing decisions are
wholly or partially made in the PCE.
1.1. TED Creation and Maintenance via IGP-TEs
Routing protocols, in particular, IGP-TEs such as Open Shortest Path
First (OSPF) and Intermediate system to intermediate system (IS-IS),
take on a number of roles with respect to the control and data planes
for IP, MPLS, and GMPLS. In all three technology families the
underlying control plane communications technology is IP and hence
all utilize the IGPs ability to control and run the IP data plane.
For the IP layer, the IGP directly establishes data plane
connectivity. In the MPLS and GMPLS cases separate signaling
protocols are used to directly control the data plane connectivity
and in these cases the prime purpose of the routing protocol is to
furnish network topology and resource status information used by path
computation algorithms on the nodes or PCEs. Hence in the IP case the
IGP is directly service impacting, while in the MPLS/GMPLS case it is
only indirectly service impacting.
The IP layer information and the MPLS/GMPLS data plane layer
information may be kept by the IGPs in two different information
stores. These are referred to as databases but are not necessarily
relational databases. In OSPF the information directly related to IP
connectivity (and hence the control communications plane for all
three technologies) and non-IP advertisements are kept in the link
state database (LSDB), while information related to traffic
engineering used by MPLS and GMPLS is kept in a (conceptually)
separate TED which can be considered a subset of the LSDB. This TED
information is distributed in a different data structure (Opaque LSA
[RFC5250]). When we talk about adding additional technology-specific
GMPLS information used for path computation we are only talking about
adding to the TED and not the IP portion of the LSDB.
There are three main functions performed by an IGP: (a) hello
protocol, (b) database synchronization (with neighbors), (c) database
updates.
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Data Plane | Hello Protocol | Database Sync
Technologies | | & Updates
--------------------------------------------------------------
IP | Establish Control & Data | LSDB
| Plane Adjacencies |
--------------------------------------------------------------
MPLS | Establish Control & Data | LSDB & TED
| Plane Adjacencies |
--------------------------------------------------------------
GMPLS | Establish Control Plane | LSDB & TED
| Adjacencies (only) |
--------------------------------------------------------------
Table 1 Main Functions of an IGP for various technologies
The procedures for maintaining LSDBs and TEDs in IGP-TEs have been
very successful and well proven over time. These consist of:
1. Ageing the individual pieces of information in the TED
(including discarding them when the information gets too old) to
remove stale information from the TED.
2. Originator of the information being required to periodically
resend TED information to prevent it from being discarded.
3. Originator of the information sending updates of information as
needed, but subject to limits on how many/often these can be
sent to keep the TED up-to-date, but to avoid swamping the
network.
4. Reliable method for getting this information to other peers
(flooding) to ensure that the information is delivered to all
participants.
5. An efficient database synchronization mechanism for sharing info
with a newly established peer.
2. Alternative TED Creation & Maintenance for a PCE
Given that nodes, by their position and role in the network, have
accurate traffic engineering information concerning their local link
ends and switching properties, it seems natural that, if other nodes
in the network cannot make use of this information or do not want it,
the information should only be conveyed to interested PCEs. In such
case the flooding of TE information to all nodes may not be very
efficient in terms of memory, CPU, bandwidth, etc.
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In addition, one could potentially choose to have some traffic
engineering information distributed via an IGP-TE while other more
specialized traffic information is only conveyed to the PCEs. For
example, it makes sense to distribute "static" (rarely modified) and
sizable data (e.g., NE switching asymmetry structure) via methods
other than IGP-TE while more frequently changed data via IGP-TE. This
could significantly decrease the IGP-TE information and its footprint
on all nodes.
The benefits of such an approach include:
o Node: reduced storage demands (doesn't keep the entire TED)
o Node: reduced processing demands for TED updates and
synchronization
o Control Plane: reduced overall communication demands since the TED
is not being updated and maintained on all nodes in the network.
o PCE: More timely TED updates are possible.
o Information distribution constraints, such as seen in [Imp-Frame]
can be met.
To quantify the previous advantages requires a bit more detail on how
such an approach could actually be accomplished. The key pieces
needed to implement such an approach include:
o Multiple PCEs must be supported for robustness and load sharing.
o Nodes must be able to find a PCE to which to send their traffic
engineering information.
o Nodes must have procedures and a mechanism (protocols) with which
to communicate their TE information to a PCE. PCEs must have
procedures and a mechanism (protocols) with which to receive this
TE information from nodes.
o Efficient mechanisms must exist in the multi-PCE case to ensure
all PCEs have the same TED.
The advantages of using an alternative to IGP-TE comes at the cost
of:
o Additional protocols to be configured and secured. Recall that we
still must have an IP IGP for control plane communications.
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o Any new protocols/implementations for alternative TED creation
still must support many IGP-TE like features such as removal of
stale information, reliable delivery of updates to all
participants, recovery after reboots/crashes/upgrades, etc.
o Node mechanisms to discover PCEs that are capable and willing to
accept direct TED updates.
2.1. Architecture Options
There are three general architectural alternatives based on how nodes
get their local TED information to the PCEs: (1) Nodes send local
information to all PCEs; (2) Nodes send local information to an
intermediate server that will send to all PCEs; (3) Nodes send local
information to at least one PCE and have the PCEs share this
information with each other. An important functionality that needs to
be addressed in each of these approaches is how a new PCE gets
initialized in a reasonably timely fashion.
Figures 1-3 show examples of three options for nodes to share local
TED information with multiple PCEs. As in the IGP case we assume that
switching nodes know their local properties and state including the
state of all their local links. In these figures the data plane links
are shown with the character "o"; TE information flow from nodes to
PCE by the characters "|", "-", "/", or "\"; and PCE to PCE TE
information, if any, by the character "i".
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---- ----
// \\ // \\
/ \ / \
| PCE \ | PCE |
| |\ / |
| X \ / \ /
|\\ // \ \ / /|\ /X
| --+-\ \ \ /// | -+-- \
| | \\ \ \\ // | | \
| | \\ \ // | | \
| | \\ \ / | | \
| | \ \\ \// | | \
| | \ \\ /\/ | | \
| | \ /X\/\ | | \
| | \ / /\ \ | | \
| | X/ / \\\ | | \
| | / \ / \\ | | \
| | // \ / \\| | \
| | / X \\\ | \
| | // /\ |\\\\| \
| +----+-/-+ / \ |+-\-|----+ \
| | | / \ || | \
| | N1 ooooooooooooooooooo N2 oo \
| | ooooooooooooooooooo ooo \
| | | / \ | | |ooo \
| +---oo---+/ \ | +------\-+ ooo \
| ooo / \ | \ ooo \
| ooo / \ | \ ooo \
| oo / * \ | \ ooo \
| oo / \ | \ ooo \
| ooo / \ | \\ ooo \
| oo / * \ \ ooo \
| ooo / \ \ ooo \
| oo / |\ \ ooo\
++--oo-/-+ |\ * \+---oo-\-+
| | | \ \ |
| oooo | \ oooo Nn |
| N3 ooooooooo +-+---\--+ ooooooooo |
| | ooooooooo | | oooooooooo | |
+--------+ oooooooo N4 oooooooo +--------+
oooo oooo
| |
+--------+
Figure 1 . Nodes send local TE information directly to all PCEs
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---- ---- ----
// \\ // \\ // \\
/ \ / \ / \
| PCE | | PCE | | PCE |
| | | | | |
\ -- \ / \ /
\\ // -- \\ // --\\ //
---- --- /--- ---- ----
-- / ----
--- / ---
-- --/- ----
--/ \\ ----
/ --
| Pub/ |
-+ Sub |
--- X ---
-- / \\ // ----
+--- / -+--\ ----+
+-----+--+ / | \ +--+-----+
| | / | \\ | |
| N1 ooooooooooooooooooooooooo N2 oooo
| ooooooooooooooooooooooooo oooo
| | / | \\ | | oo
+---oo---+ / | \+--------+ oo
oo / | \ oo
oo / | \ oo
oo / | \\ oo
oo / | \ oo
oo / * | \ oo
oo / | \ oo
oo / | \\ oo
oo / *| \ oo
oo / | \ oo
oo / | \\ oo
+---oo-/-+ | * \+---oo---+
| | | \ |
| oooo | oooo Nn |
| N3 oooooooo +---+----+ ooooooooo |
| | oooooo | | ooooooooooo | |
+--------+ oooooooo N4 ooooooooo +--------+
ooooo oooo
| |
+--------+
Figure 2 . Nodes send local TE information to PCEs via an
intermediary (publish/subscribe)server
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iiiiiiiiiiiiiiiiii
iiiiii ---- iii iiiii ----
ii ii// \\i iiiiiiii/ \\
ii / \ / \
i | PCE1 | | PCE2 |
i | | | |ii
i \ / X / ii
i \\ // // \\ // ii
i -//- / --+- i
i // // | i
i +-----/--+ +----/---+ | i
i | | | | | i
i | N1 ooooooooooooooooooooooooo N2 oooo | i
i | ooooooooooooooooooooooooo oooo | i
i | | | | oo | i
i +---oo---+ +--------+ oo | i
i oo oo | i
i oo oo | i
i oo * oo | i
i oo oo | i
i oo oo | i
i oo * oo | i
i oo oo | i
i +---oo---+ * +---oo-+-+ i
i | | | | i
i | oooo oooo Nn | i
i | N3 oooooooo +--------+ ooooooooo | i
ii | | oooooo | | ooooooooooo | | ii
i +---\----+ oooooooo N4 ooooooooo +--------+ i
i \ ooooo oooo i
ii \ | | i
i \\ +--------+ ii
ii \ --- i
ii \ ---- --- i
ii \// \-- i
ii / \ ii
ii | PCE3 | iiii
iiiii| | iiiii
\ / iii
\\ // iiiiiiiii iii
---- iiiiiiiiiiiiiiiiiii
Figure 3 . Nodes send local TE information to at least one PCE and
have the PCEs share TED information
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2.1.1. Nodes Send TE Info to all PCEs
Architectural alternative 1 shown in Figure 1, illustrates nodes
sending their local TE information to all PCEs within there domain.
As the number of PCEs grow we have scaling concerns. However,if we
are only talking about 2-3 PCEs, then we do not have this scaling
concern. In particular each node needs to keep track of which PCE it
has sent information to and update that information periodically.
If a new PCE is added to the domain the node must send all its local
TED information to that PCE rather than just sending status updates.
2.1.2. Nodes Send TE Info via an Intermediate System
Architecture alternative 2 is shown in Figure 2. This architecture
reduces the burden on switching nodes by having the nodes send TE
information to an intermediate system. This general approach is
typically described in the software literature as a publish/subscribe
paradigm. Here the nodes send their local TED information to an
intermediate entity whose job is to insure that all PCEs receive this
information. The nodes in this case being the publishers of the
information and the PCEs the subscribers of the information.
Publish/subscribe functionality can be found in general messaging
oriented middleware such as the Java Messaging Service [JMS] and many
others. A routing specific example of this approach is seen in BGP
route reflectors [RFC4456].
Note that the publish/subscribe entity can be collocated with a PCE.
This would then looks like a master/slave type system architecture.
If a new PCE is added then the intermediate server will need to work
with this new PCE to initialize its TED. Hence the publish/subscribe
entity will need to also keep a copy of the entire TED and for
reliability purposes a redundant server would be required. The
publish/subscribe entity itself can be a PCE.
Architecture alternative 2 could be useful when there are a number of
PCEs in the network and as such there is the scaling issue with each
of the NEs talking to the PCEs. The advantage of this alternative
would diminish when we are dealing only with a few PCEs.
2.1.3. Nodes Send TE Info to At Least One PCE
In this architectural alternative, shown in Figure 3, each node would
be associated with at least one PCE. This implies that each PCE will
only have partial TED information directly from the nodes. It would
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be the responsibility of a node to get its local TED information to
its associated PCE, then the PCEs within a domain would then need to
share the partial TED information they learned from their associated
nodes with each other so that they can create and maintain the
complete TED. As we have seen in section 1.1. this is very similar to
part of the functionality provided by a link state protocol, but in
this case the protocol would be used between PCEs so that they can
share the information they have obtained from their associated
switching nodes (rather than from attached links as in a regular link
state protocol). To allow for this sharing of information PCEs would
need to peer with each other. PCE discovery extensions [RFC4674]
could be used to allow PCEs to find other PCEs. If a new PCE is added
to the domain it would need to peer with at least one other PCE and
then link state protocol procedures for TED synchronization could
then be used to initialize the new PCEs TED.
A number of approaches can be used to ensure control plane resilience
in this architecture. (1) Each node can be configured with a primary
and a secondary PCE to send its information to; In case of failure of
communications with the primary PCE the node would send its
information to a secondary PCE (warm standby). (2) Each node could be
configured to send its information to two different PCEs (hot
standby).
2.2. Nodes Finding PCEs
In cases 1 and 3 nodes need to send TE information directly to PCEs.
Path Computation Clients (PCCs) and network nodes participating in an
IGP (with or without TE extensions) have a mechanism to discover a
PCE and its capabilities. [RFC4674] outlines the general
requirements for this mechanism and extensions have been defined to
provide information so that PCCs can obtain key details about
available PCEs in OSPF [RFC5088] and in IS-IS [RFC5089].
After finding candidate PCEs, a node would need to see which if any
of the PCEs actually want to receive TE information directly from
this node.
In architectural alternative 2 (publish/subscribe) the location of
intermediate system would either need to be configured or PCE
discovery could be extended so that a when a node asks a PCE if it
wants to hear TE info the PCE points it to the intermediate
publish/subscribe system.
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2.3. Node TE Information Update Procedures
First a node must establish an association between itself and a PCE
or intermediate system that will be maintaining a TED. It is the
responsibility of the node to share PCE TE information concerning its
local environment, e.g., links and node properties. General and
technology specific information models would specify the content of
this information while the specific protocols would determine the
format. Note that a node would not be sending to the PCE information
it might be passed from neighbor nodes. Note that data plane neighbor
information would be passed to the PCE embedded in TE link
information.
There will be cases where the node would have to send the PCE only a
subset of TE link information depending on the path computation
option. For instance, if the node is responsible for routing while
the PCE is responsible for wavelength assignment for the route, the
node would only need to send the PCE the WSON link usage information.
This path computation option is referred to as separate routing (R)
and wavelength assignment (WA) option in [PCE-WSON].
2.4. PCE TED Maintenance Procedures
The PCE is responsible for creating and maintaining the TED that it
will use. Key functions include:
1. Establishing and authenticating communications between the PCE
and sources of TED information.
2. Timely updates of the TED with information received from nodes,
peers or other entities.
3. Verifying the validity of information in the TED,i.e., ensure
that the network information obtained from nodes or elsewhere is
relatively timely, or not stale. By analogy with similar
functionality provided by IGPs this can be done via a process
where discrete "chunks" of TED information are "aged" and
discard when expired. This combined with nodes periodically
resending their local TE information leads to a timely TED.
3. Standardization and Protocol Considerations
In the previous section we examined a number of architectural
alternatives for TED creation and maintenance on a PCE. Here we
examine aspects of these alternatives that could be suitable for
standardization. First there are a number of items and functions that
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can be independent of the particular architectural alternatives used,
these include:
o An information model for the TED
o Basic PCE TED creation and maintenance procedures
o Information packaging for use in TED creation, maintenance and
exchange
o NE to PCE (or Pub/Sub) communication of TED information ---
interface and protocol (e.g. PCEP)
o NEs discovering PCE (or Pub/Sub) for TED creation and maintenance
purposes
By the "information model" for the TED we mean the raw information
that a path computation algorithm would work with somewhat
independent of how it might be packaged for TED maintenance and
creation. Initial efforts along these lines have started at CCAMP for
wavelength switched optical networks for non-impairment RWA [WSON-
Info] and impairment aware RWA [WSON-IMP-Info].
Given a TED information model if we can agree on basic PCE TED
creation and maintenance procedures we can then come up with a
standardized way to package the information for use in such
procedures. The analogy here is with an IGPs database maintenance
procedures such as aging and the packaging of link state information
information into LSA (link state advertisements). LSAs form the basic
chunks of an IGP's database. OSPF LSAs include an age field to assist
in the ageing procedure and also has an advertising router field that
aids in redistribution decisions, i.e., flooding. However the
detailed TE information is encoded in LSAs via type length value
(TLV) structures and it is this information that is used in path
computation.
From there we could standardize the interface between a NE and a PCE
for communication of TE information. This interface includes NE and
PCE behaviors as well as a communications protocol.
Finally for the common behaviors we need a way for the NEs to find
the PCEs or an intermediate publish/subscribe system to which they
will send their TE information. As was previously pointed out this
could be based on small enhancements to existing PCE discovery
mechanisms.
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3.1. Architecture Specific Standardization Aspects
Case 1: NEs send to all PCEs
This case has commonalities with both cases 2 and 3 and does not
appear to have unique standardization aspects. As pointed out in
section 2.1. we do need to consider when a new PCE comes online.
Case 2: Publish/Subscribe Server
In this case we would need to additionally standardize
1. how a new PCE coming online synchronizes with the
publish/subscribe server
1. how PCEs and publish subscribe server communicate
Case 3: PCE to PCE sharing TE information learned from NEs
Here we would need the following additional mechanisms standardized:
1. The PCE to PCE interface and protocol
2. The method for PCEs to discover PCEs for the purpose of TE
information sharing
3. PCE to PCE association for information sharing, in particular
sharing update information.
4. Security Considerations
This draft discusses an alternative technique for PCEs to build and
maintain a traffic engineering database. In this approach network
nodes would directly send traffic engineering information to a PCE.
It may be desirable to protect such information from disclosure to
unauthorized parties in addition it may be desirable to protect such
communications from interference (modification) since they can be
critical to the operation of the network. In particular, this
information is the same or similar to that which would be
disseminated via a link state routing protocol with traffic
engineering extensions.
5. IANA Considerations
This version of this document does not introduce any items for IANA
to consider.
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6. Conclusions
This document introduced several alternative architectures for PCEs
to create and maintain a traffic engineering database (TED) via
information directly or indirectly received from network elements and
identified common aspects of these approaches. The TED is a critical
piece of the overall PCE architecture since without it path
computations cannot proceed. Though not explicitly out of scope the
PCE working group does not have a work item or study item devoted to
TED creation and maintenance. Such a work item can lead to enhanced
interoperability and simplicity of PCE implementations. This document
identified several common areas within these alternatives that could
be standardized. In addition, the alternative approaches to TED
creation and maintenance discussed here offloads both the network
nodes and routing protocols from either some or all TED creation and
maintenance duties at the same time it does not add significant new
processing to a PCE that has already been participating in IGP based
TED creation and maintenance.
7. Acknowledgments
We would like to thank Adrian Farrel for his useful comments and
suggestions.
8. References
8.1. Normative References
[RFC4655] Farrel, A., Vasseur, J.-P., and J. Ash, "A Path Computation
Element (PCE)-Based Architecture", RFC 4655, August 2006.
[RFC4674] Le Roux, J., Ed., "Requirements for Path Computation
Element (PCE) Discovery", RFC 4674, October 2006.
[RFC5088] Le Roux, JL., Ed., Vasseur, JP., Ed., Ikejiri, Y., and R.
Zhang, "OSPF Protocol Extensions for Path Computation
Element (PCE) Discovery", RFC 5088, January 2008.
[RFC5089] Le Roux, JL., Ed., Vasseur, JP., Ed., Ikejiri, Y., and R.
Zhang, "IS-IS Protocol Extensions for Path Computation
Element (PCE) Discovery", RFC 5089, January 2008.
[RFC5250] Berger, L., Bryskin, I., Zinin, A., and R. Coltun, "The
OSPF Opaque LSA Option", RFC 5250, July 2008.
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8.2. Informative References
[JMS] Java Message Service, Version 1.1, April 2002, Sun
Microsystems.
[PCE-WSON] Y. Lee, G. Bernstein, "PCEP Requirements for the support
of Wavelength Switched Optical Networks (WSON)", work in
progress, draft-lee-pce-wson-routing-wavelength-05.txt,
February 2009.
[RFC4456] Bates, T., Chen, E., and R. Chandra, "BGP Route Reflection:
An Alternative to Full Mesh Internal BGP (IBGP)", RFC 4456,
April 2006.
[Imp-Frame] G. Bernstein, Y. Lee, D. Li, A Framework for the Control
and Measurement of Wavelength Switched Optical Networks
(WSON) with Impairments, Work in Progress, October 2008.
[WSON-Frame] Y. Lee, G. Bernstein, W. Imajuku, "Framework for GMPLS
and PCE Control of Wavelength Switched Optical Networks",
work in progress: draft-ietf-ccamp-wavelength-switched-
framework-01.txt, February 2009.
[WSON-IMP-Info] Y. Lee, G. Bernstein, "Information Model for Impaired
Optical Path Validation", work in progress: draft-
bernstein-wson-impairment-info-02.txt, March 2009.
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Author's Addresses
Greg M. Bernstein (ed.)
Grotto Networking
Fremont California, USA
Phone: (510) 573-2237
Email: gregb@grotto-networking.com
Young Lee (Editor)
Huawei Technologies
1700 Alma Drive, Suite 100
Plano, TX 75075, USA
Phone: (972) 509-5599 (x2240)
Email: ylee@huawei.com
Dan Li
Huawei Technologies Co., Ltd.
F3-5-B R&D Center, Huawei Base,
Bantian, Longgang District
Shenzhen 518129 P.R.China
Phone: +86-755-28973237
Email: danli@huawei.com
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Contributor's Addresses
Igor Bryskin
ADVA Optical
ibryskin@advaoptical.com
Daniel King
Old Dog Consulting
United Kingdom
Email: daniel@olddog.co.uk
Fabien Verhaeghe
Marben Products
176 avenue Jean Jaures
92800 Puteaux,
France
Email: fabien.verhaeghe@marben-products.com
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