Hi Dirk, et al., I'd like to point to draft-mirsky-6man-unified-id-sr <https://tools.ietf.org/html/draft-mirsky-6man-unified-id-sr-03> that proposes the use of the SRH for identifiers of 20 and 32 bits-long.
Regards, Greg On Wed, Jul 24, 2019 at 12:20 PM Dirk Steinberg <[email protected]> wrote: > Hi All, > > in todays SPRING session we have heard concerns about > MTU efficiency in certain use cases involving SRv6. > > It is true that using 128 bit SRv6 SIDs trades scalability > and flexibility against MTU overhead. There will certainly > be use cases where the additional overhead may be > justified. > > For other uses cases where MTU efficiency is a major concern > the answer within the SRv6 framework is SRv6 uSID. > > Another proposal to address the MTU efficiency problem today > advertised itself as basically using the same semantics as MPLS > encapsulated in IPv6 and also noted that SRv6 deviates from > legacy MPLS regarding label semantics. > > This is exactly the point. > > Not being dependent on the legacy MPLS label binding semantics > in SRv6 is a big advantage. > > And this advantage is carried forward in SRv6 uSID as well. > SRv6 uSID addresses the problem of MTU efficiency while > avoiding to fall back to MPLS label binding semantics. > > No separate mapping table is required to be able to forward uSID. > > It is also not true that uSID inflates the IGP and/or FIB tables > more than other approaches. A uSID is advertised just like > other SRv6 SIDs, although the prefix length will typically > be much shorter. The fact that no extra label mapping > table is required contributes to improved control and > data plane efficiency and provides excellent forwarding > ASIC efficiency, especially for low-FIB and legacy systems. > > Cheers > Dirk > > _______________________________________________ > spring mailing list > [email protected] > https://www.ietf.org/mailman/listinfo/spring >
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