Re: [Isis-wg] Proposed Changes in draft-ietf-isis-segment-routing-extensions
Jeff Tantsura <jeff.tantsura@ericsson.com> Mon, 13 April 2015 23:26 UTC
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From: Jeff Tantsura <jeff.tantsura@ericsson.com>
To: "isis-wg@ietf.org list" <isis-wg@ietf.org>
Thread-Topic: [Isis-wg] Proposed Changes in draft-ietf-isis-segment-routing-extensions
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Date: Mon, 13 Apr 2015 23:26:40 +0000
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References: <61FC3466-5350-46DF-829F-889B45F8EB92@cisco.com>, <46EAD2F6-58B7-486F-970E-0035305E79D8@alcatel-lucent.com>
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Cc: "Stefano Previdi (sprevidi)" <sprevidi@cisco.com>, "draft-ietf-isis-segment-routing-extensions@tools.ietf.org" <draft-ietf-isis-segment-routing-extensions@tools.ietf.org>
Subject: Re: [Isis-wg] Proposed Changes in draft-ietf-isis-segment-routing-extensions
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Fully support the changes proposed. Regards, Jeff > > >> On 25/03/15 12:42, "Stefano Previdi (sprevidi)" <sprevidi@cisco.com> wrote: >> >> All, >> >> The authors of draft-ietf-isis-segment-routing-extensions would >> like to expose the following proposed changes to SRGB advertisement >> which are being considered. >> >> 1. Single Vs. Multiple SRGB ranges >> Currently, section 3.1. SR-Capabilities Sub-TLV defines that: >> >> "A router not supporting multiple occurrences of the SR-Capability >> sub-TLV MUST take into consideration the first occurrence in the >> received set." >> >> The authors would like to remove above text so that a compliant >> implementation MUST support the receiving of multiple ranges. >> >> 2. Encoding the SR-Cap in a single LSP Fragment Vs. Single TLV >> Currently, section 3.1. SR-Capabilities Sub-TLV defines that: >> >> "The SR Capabilities sub-TLV (Type: TBD, suggested value 2) MAY >> appear multiple times inside the Router Capability TLV and has >> following format [...]" >> >> and >> >> "Only the Flags in the first occurrence of the sub-TLV are to be >> taken into account" >> >> and >> >> "The originating router MUST encode ranges each into a different >> SR-Capability sub-TLV and all SR-Capability TLVs MUST be encoded >> within the same LSP fragment." >> >> and >> >> "The order of the ranges (i.e.: SR-Capability sub-TLVs) in the >> LSP fragment is decided by the originating router and hence the >> receiving routers MUST NOT re-order the received ranges. This >> is required for avoiding label churn when for example a >> numerical lower Segment/Label Block gets added to an already >> advertised Segment/Label Block." >> >> Authors agreed that: >> . the encoding scheme is suboptimal and doesn't make best use of >> the TLV/LSP space (e.g.: flags field is replicated and unused). >> . we want to preserve the requirement of NOT sorting the received >> srgb ranges in order to avoid churns and downtime when a change >> is advertised (typically when the srgb is extended). >> >> Therefore a possible option is to restrict the advertisement of >> multiple srgb's into the SAME SR-Cap SubTLV where flags get >> defined once and srgb ranges encoded within the same (unique) >> SR-Cap SubTLV (btw, we still have room for up to 27 srgb ranges). >> >> Now, doing this will improve the encoding and clarity of the spec >> but introduces a backward compatibility issue with current >> version of the draft. Therefore it is important that all >> implementors make themselves known and tell the authors how >> difficult this change is from an implementation perspective. >> >> Among the authors we have 4 implementors for which the change >> seems not to be a problem but other implementations of ISIS, >> Segment Routing extension may exists and so it is necessary to >> check whether anyone has a problem with the proposed change. >> >> Thanks. >> s. >> >> _______________________________________________ >> Isis-wg mailing list >> Isis-wg@ietf.org >> https://www.ietf.org/mailman/listinfo/isis-wg > _______________________________________________ > Isis-wg mailing list > Isis-wg@ietf.org > https://www.ietf.org/mailman/listinfo/isis-wg
- [Isis-wg] Proposed Changes in draft-ietf-isis-seg… Stefano Previdi (sprevidi)
- Re: [Isis-wg] Proposed Changes in draft-ietf-isis… Uma Chunduri
- Re: [Isis-wg] Proposed Changes in draft-ietf-isis… Hannes Gredler
- Re: [Isis-wg] Proposed Changes in draft-ietf-isis… Les Ginsberg (ginsberg)
- Re: [Isis-wg] Proposed Changes in draft-ietf-isis… Chris Bowers
- Re: [Isis-wg] Proposed Changes in draft-ietf-isis… Pushpasis Sarkar
- Re: [Isis-wg] Proposed Changes in draft-ietf-isis… Uma Chunduri
- Re: [Isis-wg] Proposed Changes in draft-ietf-isis… Les Ginsberg (ginsberg)
- Re: [Isis-wg] Proposed Changes in draft-ietf-isis… Uma Chunduri
- Re: [Isis-wg] Proposed Changes in draft-ietf-isis… Uma Chunduri
- Re: [Isis-wg] Proposed Changes in draft-ietf-isis… Stefano Previdi (sprevidi)
- Re: [Isis-wg] Proposed Changes in draft-ietf-isis… Hannes Gredler
- Re: [Isis-wg] Proposed Changes in draft-ietf-isis… Les Ginsberg (ginsberg)
- Re: [Isis-wg] Proposed Changes in draft-ietf-isis… Ahmed Bashandy
- Re: [Isis-wg] Proposed Changes in draft-ietf-isis… Henderickx, Wim (Wim)
- Re: [Isis-wg] Proposed Changes in draft-ietf-isis… Pushpasis Sarkar
- Re: [Isis-wg] Proposed Changes in draft-ietf-isis… Les Ginsberg (ginsberg)
- Re: [Isis-wg] Proposed Changes in draft-ietf-isis… Chris Bowers
- Re: [Isis-wg] Proposed Changes in draft-ietf-isis… Les Ginsberg (ginsberg)
- Re: [Isis-wg] Proposed Changes in draft-ietf-isis… Pushpasis Sarkar
- Re: [Isis-wg] Proposed Changes in draft-ietf-isis… Stefano Previdi (sprevidi)
- Re: [Isis-wg] Proposed Changes in draft-ietf-isis… Ahmed Bashandy
- Re: [Isis-wg] Proposed Changes in draft-ietf-isis… bruno.decraene
- Re: [Isis-wg] Proposed Changes in draft-ietf-isis… Stefano Previdi (sprevidi)
- Re: [Isis-wg] Proposed Changes in draft-ietf-isis… Les Ginsberg (ginsberg)
- Re: [Isis-wg] Proposed Changes in draft-ietf-isis… Henderickx, Wim (Wim)
- Re: [Isis-wg] Proposed Changes in draft-ietf-isis… Jeff Tantsura
- Re: [Isis-wg] Proposed Changes in draft-ietf-isis… bruno.decraene
- Re: [Isis-wg] Proposed Changes in draft-ietf-isis… Uma Chunduri
- Re: [Isis-wg] Proposed Changes in draft-ietf-isis… Stefano Previdi (sprevidi)
- Re: [Isis-wg] Proposed Changes in draft-ietf-isis… stephane.litkowski