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CCAMP draft-srisuresh-ospf-te-00.txt
NAME OF I-D:
Title: New TE LSAs to extend OSPF for Traffic Engineering
URL:: http://www.ietf.org/internet-drafts/draft-srisuresh-ospf-te-00.txt
SUMMARY:
OSPF is a well established link state routing protocol used for
topology discovery and computing forwarding table based on
shortest-Path criteria. Traffic Engineering extensions (OSPF-TE)
will use criteria different from shortest-path so as to route
traffic around congestion paths and meet varying Service Level
agreements. OSPF-TE may also be used by non-IP networks such as
photonic and TDM (SONET/SDH) circuit switch networks for
light-path or TDM circuit setup between two end-points. The
approach outlined in this document differs from that of
[OPQLSA-TE]. The document does not suggest the use of Opaque LSAs
to add TE extensions to OSPF. Rather, new TE LSAs, modeled after
existing LSAs and flooding scope are proposed to overcome the
scaling limitations of the approach outlined in [OPQLSA-TE]. The
document draws a distinction between TE and non-TE topologies and
restricts flooding of TE LSAs into non-TE topology. The document
covers OSPF extensions for packet and non-packet networks alike,
providing a unified extension mechanism for all networks. As such,
this approach improves interoperability between peer network
elements. Lastly, the document specifies a transition path for
vendors currently using opaque LSAs to transition to using new
TE LSAs outlined here.
RELATED DOCUMENTS:
Competing documents:
[OPQLSA-TE] Katz, D., D. Yeung and K. Kompella, "Traffic
Engineering Extensions to OSPF", work in progress,
<draft-katz-yeung-ospf-traffic-05.txt>
[MAREA-TE] Kompella, K., and Y. Rekhter, "Multi-area MPLS
Traffic Engineering", Work in progress.
<draft-kompella-mpls-multiarea-te-01.txt>
Operlapping TLV definitions (Complementary to this draft):
[1] Katz, D., D. Yeung and K. Kompella, "Traffic
Engineering Extensions to OSPF", work in progress,
<draft-katz-yeung-ospf-traffic-05.txt>
[2] Kompella et al., "OSPF extensions in support of
Generalized MPLS", Work in progress,
<draft-kompella-ospf-gmpls-extensions-01.txt>
WHERE DOES IT FIT IN THE PICTURE OF THE SUB_IP WORK:
Control portion of the CCAMP box.
WHY IS IS TARGETED AT THIS WG:
By defining the TE extensions required of the OSPF routing protocol,
this document addresses the following CCAMP WG task:
- Using input from the TE working group, ensure that the signalling
and measurement protocols provide both the information and the
control functions adequate to support the traffic provisioning
and engineering operations of service providers.
JUSTIFICATION:
(1) Collecting the traffic engineering topology and characteristics
associated with TE is fundamental to provisioning traffic paths,
enforcing SLAs and carrying out the necessary engineering
operations for the service providers. This is also the information
used by the signaling protocols to communicate with the TE nodes.
The approach outlined in this document differs from that of
[OPQLSA-TE] and [MAREA-TE].
(2) The proposed mechanism is modeled after the proven OSPF LSA
formats, area heirarchy and efficient flooding scope. The mechanism
outlined overcomes the scaling limitations of the approach
outlined in [OPQLSA-TE]. A section in the document is devoted to
drawing contrast withe the Opaque-LSA based TE approach.
(3) The document draws a distinction between TE and non-TE
topologies and restricts flooding of TE LSAs into non-TE topology.
As such this makes it intuitive and for service provider SLA
enforcement on a TE network.
(4) The document provides a single unified OSPF TE extensions mechanism
for packet and non-packet networks alike. As such, this approach
improves interoperability between peer network elements.
(5) Lastly, the document specifies a transition path for vendors
currently using opaque LSAs to transition to using new
TE LSAs outlined here.
Thanks.
regards,
suresh & Paul
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