Mikael, On Sep 8, 2010, at 23:49 MDT, Mikael Abrahamsson wrote: > On Thu, 9 Sep 2010, Brian E Carpenter wrote: > >> If we do agree on this, it's very helpful, because it guides all further >> decisions. For example, it allows us to see that the label is immutable on a >> best effort basis, rather than mathematically immutable. So we ccould say >> both that forwarding nodes MUST NOT change the label, *and* that downstream >> nodes MUST NOT rely on the value being unchanged. > > Last I checked, the standards said that if precedence/dscp changed, the host > should reset the session (correct me if I'm wrong, I don't really have time > to check it right now). > > In real life, ISPs consider DSCP as one thing they have the right to change > (along with TTL) in transit. I can imagine the flow label being considered > the same thing regardless of what the standard says. > > For me, the flow label would be most useful in tunnel scenarios. We have > mobile base station controllers which outputs hundreds of megabits/s of > tunneled packets and this is all between the same SRC/DST IP. The way 3GPP > does things, this is only going to increase. Being able to use flow labels to > identify an individual user tunnel and thus being able to hash more > efficiently when doing load sharing would be most beneficial.
With respect to your last two paragraphs, we're trying to do just that for packets tunneled over IPv6. Take a look at the following: http://tools.ietf.org/html/draft-carpenter-flow-ecmp-02 IMHO, there seems to be agreement that since a Tunnel End-Point is the "source node" of the tunnel packets that having it write a flow-label into the outermost IPv6 header is alignment with RFC 3697. The larger debate seems centered around plain (non-tunneled) IPv6 packets and what, how, when, etc. the flow-label should be written into them. -shane -------------------------------------------------------------------- IETF IPv6 working group mailing list [email protected] Administrative Requests: https://www.ietf.org/mailman/listinfo/ipv6 --------------------------------------------------------------------
