Re: [Lsr] I-D Action: draft-ietf-lsr-flex-algo-14.txt

Peter Psenak <> Fri, 19 February 2021 12:07 UTC

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From: Peter Psenak <>
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Date: Fri, 19 Feb 2021 13:07:38 +0100
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Subject: Re: [Lsr] I-D Action: draft-ietf-lsr-flex-algo-14.txt
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these are larger, but important change and we would like the WG to 
review them. Changes are mostly OSPF specific, except the last item 
which is an editorial one.

The changes include:

1. introduction of the OSPFv2 Extended Inter-Area ASBR LSA, OSPFv2 
Extended Inter-Area ASBR TLV and OSPF Flexible Algorithm ASBR Metric 
Sub-TLV. These are used to advertise the FA specific inter-area metric 
for the ASBRs, similar to what the FAPM does for prefixes. We clearly 
missed these originally.

2. introduction of the E-bit in the OSPF OSPF FAPM Sub-TLV to support 
the OSPF external metric types for FA. This was also missed originally.

3. related clarifications in "Multi-area and Multi-domain 
Considerations" section related to the above.

4. updated IANA sections as a result of (1) and (2).

5. clarification of the ASLA usage in presence of the L-bit - this has 
been requested by Tony. No functional change, just an editorial change 


On 19/02/2021 12:59, wrote:
> A New Internet-Draft is available from the on-line Internet-Drafts directories.
> This draft is a work item of the Link State Routing WG of the IETF.
>          Title           : IGP Flexible Algorithm
>          Authors         : Peter Psenak
>                            Shraddha Hegde
>                            Clarence Filsfils
>                            Ketan Talaulikar
>                            Arkadiy Gulko
> 	Filename        : draft-ietf-lsr-flex-algo-14.txt
> 	Pages           : 44
> 	Date            : 2021-02-19
> Abstract:
>     IGP protocols traditionally compute best paths over the network based
>     on the IGP metric assigned to the links.  Many network deployments
>     use RSVP-TE based or Segment Routing based Traffic Engineering to
>     steer traffic over a path that is computed using different metrics or
>     constraints than the shortest IGP path.  This document proposes a
>     solution that allows IGPs themselves to compute constraint-based
>     paths over the network.  This document also specifies a way of using
>     Segment Routing (SR) Prefix-SIDs and SRv6 locators to steer packets
>     along the constraint-based paths.
> The IETF datatracker status page for this draft is:
> There are also htmlized versions available at:
> A diff from the previous version is available at:
> Please note that it may take a couple of minutes from the time of submission
> until the htmlized version and diff are available at
> Internet-Drafts are also available by anonymous FTP at:
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