Hi Shane,
On Aug 5, 2009, at 12:50 PM, Shane Amante wrote:
To bring this back up a level, while it's /possible/ to encourage vendors to adopt the IPv6 flow-label as input-keys to their hash- calculations for LAG/ECMP, it takes [a lot] of time to see that materialize in the field. Practically, you're probably looking at somewhere between, at best, a 3 - 5 year window, before it will actually appear in live, production networks, given that it has to be prioritized for development at the vendor, tested, released in software, then re-tested by the SP and, finally, deployed. That's not an "easy" process that happens in the blink-of-an-eye. That's not to say that we (SP's) should not "encourage" vendors to do this, anyway, (we are/will) however if LISP (or other protocols like it that depend on tunneling) quickly gain traction, we need a way to deal with these traffic flows in our networks today, without telling customers: "turn off protocol <FOO>, because we can't deliver your packets".
ECMP of LISP flows is an optimization that only matters when there is a large amount of LISP traffic, right? Do you think there is a reasonable chance that LISP would be widely-enough to deployed to require this optimization in less than 3-to-5 years?
Perhaps one way to satisfy the parties in this conversation would be something along the following lines: - LISP, and other protocols that wish to use tunneling, adopt UDP- lite (or UDP w/ 0 checksums) as a MUST for near-term deployment; - LISP, and other protocols that wish to use tunneling, adopt IP-in- IPv6 tunneling with a flow-label required in the outer IPv6 header as a "SHOULD" for medium- to long-term deployments. ... assuming vendors successfully adopt the IPv6 flow-label as input- keys in their hash calculations at some point in the future, we come back and deprecate the UDP/IPv6 tunnel method and elevate IP-in-IPv6 w/ flow-labels to a MUST.
I would agree to this statement if one of two things were to happen: (1) we were to remove "(or UDP w/0 checksums) -- making UDP-Lite a MUST in the near term", or (2) we were to satisfy ourselves that using zero checksums will not represent an operational problem for LISP, or for other applications that need to co-habitate with LISP, and we were to add a normative dependency on a document (like Marshall's, with edits) that would allow the use of UDP w/0 checksums over IPv6 in some cases, with LISP being an example of a case where this was appropriate.
Margaret -------------------------------------------------------------------- IETF IPv6 working group mailing list ipv6@ietf.org Administrative Requests: https://www.ietf.org/mailman/listinfo/ipv6 --------------------------------------------------------------------
