Split flows across Domains

Tue Jan 24 18:20:13 UTC 2006

Joe Abley <jabley at isc.org> writes:

> On 24-Jan-2006, at 13:09, Robert E.Seastrom wrote:
>
>> Joe Abley <jabley at isc.org> writes:
>>
>>> If you can get two candidate routes for the same destination into the
>>> FIB, then you'll get per-flow load balancing as long as CEF is
>>> running, no?
>>
>> Yes and no.  CEF is {src, dst} hash IIRC, and "per-flow" usually means
>> {src, srcport, dst, dstport, [proto, tos]} hash in my experience.
>
> Even if the hash is only calculated over source and destination IP
> addresses, the end effect is still that packets associated with a
> single flow still follow the same route where there is more than one
> candidate route available.

And conversely, that different flows that ought to be load-balanced
aren't.  But we're splitting semantic hairs here...  ;-)

                                        ---rob