Across the DC space in general most providers use NVO3 and vxlan source port entropy L2/L3/L4 hash which provides per packet uniform 50/50 load balancing at the L2 VNI overlay layer, which translates into underlay load balancing of flows and thus no polarization.
Across the DC space speaking from an operators perspective as under the floor fiber is not at a premium compare to 100G facilities costs the net addition of bandwidth can be done fairly quickly so you are ahead of the congestion curve and can be proactive versus reactively upgrading bandwidth piecemeal here and there ad hoc. There still maybe cases that still arise as even if you have the fiber infrastructure available, it’s not easy to upgrade and flash every link simultaneously in the DC in one or multiple maintenance windows, so you could still be left with some uneven bandwidth across the DC that could utilize this feature. DC comes into play for PE-CE “wan links”as well use case for unequal cost load balancing use of the cumulative link bandwidth community regenerated. I think the use case where both the iBGP P core P-P links or eBGP PE - PE inter-as are all wan links where link upgrades tend to not get done in unison uniformly, and in those cases both iBGP link bandwidth community can be heavily utilized as well as eBGP cumulative regenerated link bandwidth community for unequal cost load balancing. Across the core as well it is hard to flash all links even under floor fiber to the same bandwidth all at once you are left with the requirement for unequal coat load balancing. As operators upgrade their DC as well as core infrastructure to IPv6 forwarding plane in the move towards SRv6, they can now take advantage of flow label entropy stateless uniform load balancing and elimination of polarization. However, the wan link upgrades of core and DC PE-CE still exists and thus may be done piecemeal, so then both of the drafts are an extremely helpful tool for operators that much need the unequal cost load balancing capability. I support both drafts. Have most vendors implemented this to support both 2 byte and 4 byte AS extended community. The drafts state 2 byte AS support. Thanks Gyan On Tue, May 25, 2021 at 7:00 PM Robert Raszuk <[email protected]> wrote: > Hi Arie, > > Draft draft-ietf-idr-link-bandwidth talks about advertising towards > IBGP. It does not talk about advertising over EBGP. > > While I do support your use case I think it would be much cleaner to just > ask for new ext. community type. > > Reason being that as you illustrate you may want to accumulate BGP path's > bw across few EBGP hops in the DC. Today there is no way to do so unless > you want to completely hijack current lb ext community. > > Also I see an analogy here to AIGP RFC although it clearly fits rather > poorly for those who use BGP as IGP :). > > Best, R. > > On Wed, May 26, 2021 at 12:22 AM Arie Vayner <[email protected]> wrote: > >> Jeff, >> >> Actually, the way this draft is written, and how the implementations I'm >> aware of are implemented, this is not really a transitive community. It is >> a new community that is being generated on the AS boundary. >> The community value is not carried over, but is calculated based on an >> cumulative value of other received communities, and then advertised as a >> new value across the AS boundary. >> >> Tnx, >> Arie >> >> On Tue, May 25, 2021 at 12:55 PM Jeff Tantsura <[email protected]> >> wrote: >> >>> Hi, >>> >>> I support adoption of the draft as Informational, please note, that >>> request to change transitivity characteristics of the community is >>> requested in another draft. >>> Gyan - please note, while pretty much every vendor has implemented the >>> community and relevant data-plane constructs, initial draft defines the >>> community as non transititive, some vendors have followed that while some >>> other have implemented it a transitive (to support obvious use case - eBGP >>> in DC). >>> >>> >>> Cheers, >>> Jeff >>> On May 22, 2021, 8:38 AM -0700, Satya Mohanty (satyamoh) <satyamoh= >>> [email protected]>, wrote: >>> >>> Hi all, >>> >>> >>> >>> On behalf of all the authors, we request a discussion of the draft >>> https://datatracker.ietf.org/doc/html/draft-mohanty-bess-ebgp-dmz-03 >>> and subsequent WG adoption. >>> >>> This draft extends the usage of the DMZ link bandwidth to scenarios >>> where the cumulative link bandwidth needs to be advertised to a BGP speaker. >>> >>> Additionally, there is provision to send the link bandwidth extended >>> community to EBGP speakers via configurable knobs. Please refer to section >>> 3 and 4 for the use cases. >>> >>> >>> >>> This feature has multiple-vendor implementations and has been deployed >>> by several customers in their networks. >>> >>> >>> >>> Best Regards, >>> >>> --Satya >>> _______________________________________________ >>> BESS mailing list >>> [email protected] >>> https://www.ietf.org/mailman/listinfo/bess >>> >>> _______________________________________________ >>> BESS mailing list >>> [email protected] >>> https://www.ietf.org/mailman/listinfo/bess >>> >> _______________________________________________ >> BESS mailing list >> [email protected] >> https://www.ietf.org/mailman/listinfo/bess >> > -- <http://www.verizon.com/> *Gyan Mishra* *Network Solutions A**rchitect * *Email [email protected] <[email protected]>* *M 301 502-1347*
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