I’m planning to have a presentation in RTGWG that would explain RTO based header changes/ aka self healing fabie (flow label in v6/ overlay transport layer source port in v4, in linux kernel since 2016), stay tuned. This is mostly relevant to DC domain and while host based still a very important improvement.
Cheers, Jeff > On Jul 14, 2021, at 18:21, Gyan Mishra <hayabusa...@gmail.com> wrote: > > > All > > I think I figured out how “source port entropy” works and provides “better” > load balancing then traditional IGP & EGP based ECMP underlay algorithms that > are subject to polarization. > > So normally w/o source port entropy vxlan feature the overlay NVE Anycast > vtep tunnel as a tunnel source and destination so as it’s a single source / > destination IP for the vtep tunnel termination, so that would get pinned to a > single path similar to L2 VPN service label, single source / destination PE > to PE single path. So just as with L2 VPN you have the FAT PW which now you > read into the payload and extract the src/dest flows and can now load balance > the flows over Ethernet bundles. > > Similarly with VXLAN “source port entropy” per RFC 7348 the L2/L3/L4 headers > 5-tuple hash is used to generate the outer header udp source port which is > used as the input key to the hashing function. So one of the major > advantages of VXLAN is now traffic can be much more uniformly evenly load > balanced now with 5-tuple info over L3 ECMP path as compare to traditional > IPv4 flow based per session source / destination hash load balancing. > > The vxlan 5-tuple hash input key to hash function is also very similar > analogous to IPv6 flow label RFC 6437 5-tuple header hash input key to hash > function stateless mode flow label uniform load balancing. > > > Kind Regards > > Gyan >> On Wed, Jul 14, 2021 at 6:11 PM Gyan Mishra <hayabusa...@gmail.com> wrote: >> >> Dear BESS Experts >> >> ?? On NVO3 VXLAN overlay encapsulation >> >> My understanding of VXLAN source port entropy is to provide uniform load >> balancing similar to RFC 6437 IPv6 flow label uniform stateful load >> balancing, in NVO3 VXLAN context, using header 5-tuple L2/L3/L4 hash and >> generating source port input key to hash function for per packet per flow >> uniform load balancing as achieved with EVPN ECMP pr weighted UCMP MHD MLAG >> PE-CE AC. >> >> The problem with L3 ECMP and weighed UCMP is the Day 1 well known TCP >> polarization of flows where high bandwidth flows are not evenly distributed >> between L3 paths. >> >> So the question is does source port entropy provide per RFC 7348 excerpt >> below provide per packet per flow load balancing or flow based where all >> packets that are part of the same flow get hashed to the same path. >> >> Outer UDP Header: This is the outer UDP header with a source port >> provided by the VTEP and the destination port being a well-known >> UDP port. >> >> - Destination Port: IANA has assigned the value 4789 for the >> VXLAN UDP port, and this value SHOULD be used by default as the >> destination UDP port. Some early implementations of VXLAN have >> used other values for the destination port. To enable >> interoperability with these implementations, the destination >> port SHOULD be configurable. >> >> - Source Port: It is recommended that the UDP source port number >> be calculated using a hash of fields from the inner packet -- >> one example being a hash of the inner Ethernet frame's headers. >> This is to enable a level of entropy for the ECMP/load- >> balancing of the VM-to-VM traffic across the VXLAN overlay. >> When calculating the UDP source port number in this manner, it >> is RECOMMENDED that the value be in the dynamic/private port >> range 49152-65535 [RFC6335]. >> >> >> Kind Regards >> >> Gyan >> >> >> -- >> >> >> Gyan Mishra >> Network Solutions Architect >> Email gyan.s.mis...@verizon.com >> M 301 502-1347 >> >> > -- > > > Gyan Mishra > Network Solutions Architect > Email gyan.s.mis...@verizon.com > M 301 502-1347 > > > _______________________________________________ > BESS mailing list > BESS@ietf.org > https://www.ietf.org/mailman/listinfo/bess
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