INTERNET-DRAFT Tomohiro Otani
Intended status: Informational Kenichi Ogaki
Expires:August 2008 KDDI R&D Labs
February 24, 2008
Requirements for GMPLS applications of PCE
Document: draft-otani-pce-gmpls-aps-req-01.txt
Status of this Memo
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Abstract
The initial effort of PCE WG is specifically focused on MPLS (Multi-
protocol label switching). As a next step, this draft describes
functional requirements for GMPLS (Generalized MPLS) application of
PCE (Path computation element).
Table of Contents
Status of this Memo................................................ 1
Abstract........................................................... 1
1. Introduction.................................................... 3
2. Conventions used in this document............................... 3
3. GMPLS applications of PCE....................................... 3
4. Requirement for GMPLS application of PCE........................ 5
5. Security consideration.......................................... 5
6. Acknowledgement................................................. 5
7. Intellectual property considerations............................ 5
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8. Informative references.......................................... 6
Author's Addresses................................................. 7
Document expiration................................................ 7
Copyright statement................................................ 7
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1. Introduction
The initial effort of PCE WG is focused on solving the path
computation problem over domains in MPLS networks. As the same case
with MPLS, service providers (SPs) have also come up with
requirements for path computation in GMPLS networks such as TDM-based
or Ethernet-based networks as well.
[PCE-ARCH] and [PCECP-REQ] discuss the framework and requirements for
PCE on both packet MPLS networks and (non-packet switch capable)
GMPLS networks. This document complements these documents by
providing some consideration of GMPLS applications in the inter-
domain networking environment and indicating a set of requirements
for the extended definition of series of PCE related protocols.
Constraint based shortest path first (CSPF) computation within a
domain or over domains for signaling GMPLS Label Switched Paths
(LSPs) is more stringent than that of MPLS LSPs [MPLS-AS], because
the additional constraints, e.g., interface switching capability,
link encoding, link protection capability and so forth need to be
considered to establish GMPLS LSPs [CSPF]. GMPLS signaling protocol
[RFC3471, RFC3473] is designed taking into account bi-directionality,
switching type, encoding type, SRLG, and protection attributes of the
TE links spanned by the path, as well as LSP encoding type and
switching type for the end points, appropriately.
This document provides the investigated results of GMPLS applications
of PCE especially for the support of GMPLS inter-domain path
computation. This document also outlines GMPLS inter-domain
architecture, and provides requirements for GMPLS applications of PCE
in the GMPLS inter-domain environment.
2. Conventions used in this document
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 RFC-2119 [RFC2119].
3. GMPLS applications of PCE
3.1 GMPLS network model
Figure 1 depicts a typical network, consisting of several GMPLS
domains, assumed in this document. D1, D2, D3 and D4 have multiple
GMPLS inter-domain connections, and D5 has only one GMPLS inter-
domain connection. These domains follow the definition in [RFC4726].
+---------+
+---------|GMPLS D2|----------+
| +----+----+ |
+----+----+ | +----+----+ +---------+
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|GMPLS D1| | |GMPLS D4|---|GMPLS D5|
+----+----+ | +----+----+ +---------+
| +----+----+ |
+---------|GMPLS D3|----------+
+---------+
Figure 1: GMPLS Inter-domain network model.
Each domain is configured using various switching and link
technologies defined in [Arch] and an end-to-end route needs to
respect TE link attributes like multiplexing type, encoding type,
etc., making the problem a bit different from the case of classical
(packet) MPLS. In order to route from one GMPLS domain to another
GMPLS domain appropriately, each domain manages traffic engineering
database (TED) by PCE, and exchanges or provides route information of
paths, while concealing its internal topology information.
3.2 Path computation in GMPLS network
[CSPF] describes consideration of GMPLS TE attributes during path
computation.
Ingress Transit Egress
+-----+ link1-2 +-----+ link2-3 +-----+ link3-4 +-----+
|Node1|------------>|Node2|------------>|Node3|------------>|Node4|
| |<------------| |<------------| |<------------| |
+-----+ link2-1 +-----+ link3-2 +-----+ link4-3 +-----+
Figure 2: Path computation in GMPLS networks.
For the simplicity in consideration, the below basic assumptions are
made when the LSP is created.
(1) Switching capabilities of outgoing links from the ingress
and egress nodes (link1-2 and link4-3 in Figure 1) must be
consistent with each other.
(2) Switching capabilities of all transit links (link2-3 and
link3-2) including incoming links to the ingress and egress
nodes (link2-1 and link3-4) should be consistent with
switching type of a LSP to be created.
(3) Encoding-types of all transit links (link1-2, link2-1,
link2-3, link3-2, link3-4 and link4-3 in Figure 1) should be
consistent with encoding type of a LSP to be created.
[CSPF] indicates the possible table of switching capability, encoding
type and bandwidth at the ingress link, transiting links and the
egress link which need to be satisfied with the created LSP. This
table assumes the single layer network control.
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4. Requirement for GMPLS application of PCE
In this section, we describe requirements for GMPLS applications of
PCE in order to establish GMPLS LSP over domains.
4.1 PCE requirements
As for path computation in GMPLS networks as discussed in section 3,
the PCE needs to consider the GMPLS TE attributes appropriately
according to tables in [CSPF] once a PCC or another PCE requests a
path computation. Indeed, the path calculation request message from
the PCC or the PCE needs to contain the information specifying
appropriate attributes. Additional attributes to those already
defined in [PCECP] are as follows.
(1) Switching capability: PSC1-4, L2SC, TDM, lambda, LSC, FSC
(2) Encoding type: as defined in [RFC4202], [RFC4203], e.g., Ethernet,
SONET/SDH, Lambda, etc.
(3) Path protection type: as defined in [RFC4872], e.g., 1+1
protection, 1:1 protection, (pre-planned) rerouting, etc.
4.2 PCC requirements
As described above, a PCC needs to support to initiate path
computation request specifying abovementioned attributes. Afterwards,
GMPLS signaling will be invoked according to the responded messages
from the PCE.
4.3 GMPLS PCE Management
PCE related Management Information Bases need to consider extensions
to be satisfied with requirements for GMPLS applications. For
extensions, [GMPLS-TEMIB] are defined to manage TE database and may
be referred to accommodate GMPLS TE attributes in the PCE.
5. Security consideration
PCE extensions to support GMPLS should be considered under the same
security as current work. This extension will not change the
underlying security issues.
6. Acknowledgement
The author would like to express the thanks to S. Okamoto for his
comments.
7. Intellectual property considerations
The IETF takes no position regarding the validity or scope of any
Intellectual Property Rights or other rights that might be claimed to
pertain to the implementation or use of the technology described in
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this document or the extent to which any license under such rights
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The IETF invites any interested party to bring to its attention any
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ipr@ietf.org.
8. Informative references
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[PCE-ARCH] A. Farrel, et al, "A Path Computation Element (PCE)-
Based Architecture", RFC4655, Aug., 2006.
[PCECP-REQ] J. Ash, et al, "Path computation element (PCE)
communication protocol generic requirements", RFC4657,
Sept., 2007.
[MPLS-AS] R. Zhan, et al, "MPLS Inter-Autonomous System (AS)
Traffic Engineering (TE) Requirements", RFC4216,
November 2005.
[CSPF] T. Otani, et al, "Considering Generalized
Multiprotocol Label Switching Traffic Engineering
Attributes During Path Computation", draft-otani-
ccamp-gmpls-cspf-constraints-07.txt, Nov., 2007.
[RFC3471] Berger, L., "Generalized Multi-Protocol Label
Switching (MPLS) Signaling Functional Description",
RFC 3471, January 2003.
[RFC3473] Berger, L., "Generalized Multi-Protocol Label
Switching (MPLS) Signaling - Resource ReserVation
Protocol Traffic Engineering (RSVP-TE) Extensions",
RFC 3473, January 2003.
[RFC4726] A. Farrel, et al, "A framework for inter-domain MPLS
traffic engineering", RFC4726, November 2006.
[Arch] E. Mannie, et al, "Generalized Multi-Protocol Label
Switching Architecture", RFC3945, October, 2004.
[PCECP] JP. Vasseur, et al, "Path Computation Element (PCE)
Communication Protocol (PCEP)", draft-ietf-pce-pcep-
10.txt, Feb., 2008.
[RFC4202] K. Kompella, and Y. Rekhter, "Routing Extensions in
Support of Generalized Multi-Protocol Label
Switching", RFC4202, Oct. 2005.
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[RFC4203] K. Kompella, and Y. Rekhter, "OSPF Extensions in
Support of Generalized Multi-Protocol Label
Switching", RFC4203, Oct. 2005.
[RFC4872] J.P. Lang, Ed., "RSVP-TE Extensions in Support of
End-to-End Generalized Multi-Protocol Label Switching
(GMPLS) Recovery", RFC4872, May 2007.
[GMPLS-TEMIB] T. Nadeau and A. Farrel, Ed., "Generalized
Multiprotocol Label Switching (GMPLS) Traffic
Engineering Management Information Base", RFC4802,
Feb. 2007.
Author's Addresses
Tomohiro Otani
KDDI R&D Laboratories, Inc.
2-1-15 Ohara Kamifukuoka Saitama, 356-8502. Japan
Phone: +81-49-278-7357
Email: otani@kddilabs.jp
Kenichi Ogaki
KDDI R&D Laboratories, Inc.
2-1-15 Ohara Kamifukuoka Saitama, 356-8502. Japan
Phone: +81-49-278-7897
Email: ogaki@kddilabs.jp
Document expiration
This document will be expired in August 31, 2008, unless it is
updated.
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