Hi Joel, Options are really bad for fast path processing. To find an option, the entire list of TLV's needs to be parsed, which is really hard especially when you have a limited number of clock cycles.
For end-to-end processing however options can be considered better (especially if the traffic is CPU bound and not BFD or some other application). Though there are issues even there. Assume a case where we need to prioritize OSPFv3 packets to the CPU, we need to put multiple such filters for the same, as the OSPFv3 header can come after a bunch of IPv6 headers. Thanks, Vishwas On Thu, Feb 3, 2011 at 7:11 PM, Joel M. Halpern <j...@joelhalpern.com> wrote: > Lets be a little careful here: > 1) If we say "No Extension Headers for intermediate processing", and "No Hop > By Hop Options", then we are saying that we do not want any extensions > intended to be processed in intermediate routers. While I personally like > that, I want to make really sure that we understand that is what we are > saying. > > 2) I have been told that many large rotuers have a setting that causes them > to ignore the hop by hop options field. To the degree that is both true and > turned on, then we need to allow for that in our think (both positive and > negative.) > > Yours, > Joel > > On 2/3/2011 9:57 PM, Christopher Morrow wrote: >> >> On Thu, Feb 3, 2011 at 8:09 PM, Hing-Kam (Kam) Lam<hingka...@gmail.com> >> wrote: >>> >>> The below white paper from Cisco asserts that most vendors including >>> Cisco process Hop-by-Hop extension headers in CPU (slow path). Is this >>> correct? >>> >>> >>> http://www.cisco.com/en/US/technologies/tk648/tk872/technologies_white_paper0900aecd8054d37d.html >>> >>> If Yes, then we should not add support for more sub options with HBH >>> header. >> >> yes, see notes from me (in particular) about this from the last 2+ >> years... no more HBH header options pls... OR understand that these >> may/will get dropped (probably the whole packet actually) at some >> provider edges. >> -------------------------------------------------------------------- >> IETF IPv6 working group mailing list >> ipv6@ietf.org >> Administrative Requests: https://www.ietf.org/mailman/listinfo/ipv6 >> -------------------------------------------------------------------- >> > -------------------------------------------------------------------- > IETF IPv6 working group mailing list > ipv6@ietf.org > Administrative Requests: https://www.ietf.org/mailman/listinfo/ipv6 > -------------------------------------------------------------------- > -------------------------------------------------------------------- IETF IPv6 working group mailing list ipv6@ietf.org Administrative Requests: https://www.ietf.org/mailman/listinfo/ipv6 --------------------------------------------------------------------
