Internet DRAFT - draft-chetan-lspid-ospf
draft-chetan-lspid-ospf
INTERNET DRAFT
Expiration Date: September 2002
Chetan Kumar S
Wipro Technologies
Sunil Kumar
Wipro Technologies
March 2002
Signalling LSPID's in OSPF TE
draft-chetan-lspid-ospf-00.txt
Status of this Memo
This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC2026.
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Abstract
This draft introduces new a sub TLV to OSPF TE extensions to signal
the LSPID (Label Switch Path ID) of an LSP (Label Switch Path).
This information can be used by any mechanism (normally constraint
based path calculation (CSPF) procedures) to calculate paths that
may contain LSPID's as one its Explict Route Objects.
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1. Conventions Used in this Document
CRLDP : Constraint-Based LDP
CSPF : Constraint Shortest Path First
LDP : Label Distribution Protocol
E-LSPs : Explicitly routed LSPs
ERO : Explicit Route Object
ERTLV : Explicit Route TLV
2. Introduction
This document introduces an additional traffic engineering
attribute describing LSPID (Label Switch Path ID) [CRLDP] to TE
parameters documented in [OSPF-TE]. LSPID could be used by the CSPF
path computation mechanism to generate Explicit Route Objects that
may include LSPID as one of the objects.
LSPID of an LSP tunnel is described as one of the Sub-TLVs in the
Link TLV for the tunnel.
Note: The LSPs can be advertised into IGP by other ways as
described in [UNNUM] [LSP-HIER].
3. Overview
CR-LDP provides a mechanism to setup LSPs based on constraint
routing. Explicit Label Switch Paths (E-LSP) which are constrained
by a set of Explicit Route Objects (ERO) are essential requirements
of traffic engineering. CRLDP specifies four different EROs for
signalling, viz. IPv4 prefix, IPv6 prefix, Autonomous system number
and LSPID.
LSPID is a unique identifier of a CR-LSP within an MPLS network.
When an ERO that contains LSPID ERTLV is carried in the CRLDP label
request the path selected would be tunneled(/spliced) through this
CRLSP.
A TE path can normally be calculated using a high level software
objects like CSPF, which may reside on a single node, which has the
complete information about nodes and tunnels in the network.
Automated procedures to calculate a constrained based path help in
reducing a lot of administrative overhead. Moreover,
administratively selected paths may be inconsistent or illogical due
to operator error and the selected paths may not be optimal.
Some of the advantages of automating the CSPF calculations are as
follows.
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a) A new LSP request can be triggered automatically on failure of
an existing LSP.
b) A single node can perform CSPF calculation and provide optimized
paths in the whole network.
c) Easy inter-operations with various vendor implementations that
signal the path attributes.
However none of the existing IGP protocols, with their extensions
there of, carry the information about the LSPID therby forcing
operator interventions for setting up paths that pass through LSP
tunnels. Administrator will have to know apriori, the LSPIDs in the
MPLS network domain and update the same in the ERO's calculated by
the CSPF. In this draft we add LSPID sub TLV to the OSPF TE
extensions to signal the LSPID TLV into the IGP. This provides CSPF
object or any other mechanism with the complete information to
construct the EROs.
3. LSPID Sub-TLV
The Link TLV describes a single link.
The following sub-TLVs are currently defined in [OSPF-TE]:
1 - Link type (1 octet)
2 - Link ID (4 octets)
3 - Local interface IP address (4 octets)
4 - Remote interface IP address (4 octets)
5 - Traffic engineering metric (4 octets)
6 - Maximum bandwidth (4 octets)
7 - Maximum reservable bandwidth (4 octets)
8 - Unreserved bandwidth (32 octets)
9 - Resource class/color (4 octets)
32768-32772 - Reserved for Cisco-specific extensions
This document introduces LSPID sub-TLV. LSPID Sub-TLV specifies
LSPID of the tunnel being advertised in the LINK TLV.
Type field for LSPID sub-TLV is TBD (refer section 7).
This sub-TLV is of length 6 octets.
The value of this TLV is as defined in the CRLDP specifications
which is composed of LSP tunnel ingress LSR Router ID (or any of
its own IPv4 addresses), Refer to [CRLDP] for more information.
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Internet Draft draft-chetan-lspid-ospf-00.txt March 2002
6. Security Considerations
This document raises no new security issues for OSPF. The security
mechanisms already proposed for OSPF may be used.
7. IANA Considerations
The type value for the LSPID is to be obtained from IANA.
8. Acknowledgments
Authors would like to thank RaviShankar, Nagabhusna and Venkat for
discussion on the idea.
9. References
[CRLDP] Jamoussi, et al., "Constraint-Based LSP Setup using LDP"
RFC 3212, January 2002.
[LSP-HIER] Kireeti Kompella, Yakov Rekhter, "LSP Hierarchy with
Generalized MPLS TE" (work in progress).
[OSPF-TE] Dave Katz, Derek Yeung, Kireeti Kompella, "Traffic
Engineering Extensions to OSPF", (work in progress)
[UNNUM] Kireeti Kompella, Yakov Rekhter, Alan Kullberg "Signalling
Unnumbered Links in CR-LDP", (work in progress).
10. Author's Address
Chetan Kumar S
Wipro Technologies
Hosur Road, Bomanahalli
Bangalore-5600
India
Phone : 91-80-5732296
Fax : 91-11-5732296
Email : chetan.kumar@wipro.com
Sunil Kumar
Wipro Technologies
Hosur Road, Bomanahalli
Bangalore-5600
India
Phone : 91-80-5732296
Fax : 91-11-5732296
Email : sunil.kum@wipro.com
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