On Tue, Feb 13, 2018 at 01:03:14PM +0200, Or Gerlitz wrote: > On Tue, Feb 13, 2018 at 2:05 AM, David Ahern <dsah...@gmail.com> wrote: > > Hardware supports multipath selection using the standard L4 5-tuple > > instead of just L3 and the flow label. In addition, some network > > operators prefer IPv6 path selection to use the 5-tuple. > > The HW supports using flow label and AFAIK that is the preferred approach > by the community (?) > > > To that end, add support to IPv6 for multipath hash policy > > so a question comes up if/what are the disadvantaged > to support 5-tuple. E.g Tom was commenting that such DPI is problematic > when multiple IPv6 header extensions are used.
Tom is much more qualified to answer this, but I think the problem is that the flow label isn't always set. Also, apparently some devices change the flow label mid flow. See: "At Fastly, this hashing is performed by an Ethernet switch ASIC, and to avoid breakage, the IPv6 hashing function must not include the flow label. As in IPv4, the hash function includes the source and destination information in the L3 and L4 headers." https://blog.apnic.net/2018/01/11/ipv6-flow-label-misuse-hashing/ https://www.youtube.com/watch?v=b0CRjOpnT7w https://pc.nanog.org/static/published/meetings/NANOG71/1531/20171003_Jaeggli_Lightning_Talk_Ipv6_v1.pdf