[c-nsp] Load balancing outbound traffic with BGP

[Simon Leinen]

Giles Coochey writes:
>> Quoting oles at ovh.net:
>> >> bgp bestpath as-path multipath-relax

> Might this have an adverse effect on jitter sensitive applications
> such as VoIP?

"VoIP using badly written software (VoBS)", you mean?

That depends on how the multiple paths are used by your routers'
forwarding mechanisms.  CEF multipath usually hashes over
source+destination IP address, so all traffic between a pair of hosts
should use the same path.

The Cat6500/7600 has an option where (TCP/UDP) port numbers are also
included in the hash, so traffic between a single pair of hosts could
use multiple paths, but all packets of a single transport connection
(TCP or UDP) would stay on the same path.

I.e. if you have a fancy stereophonic VoIP implementation that uses
one RTP flow for each channel, then that application should have
extra-good jitter buffering in case the left-ear samples use a
different path from the right-ear samples.

But all real-time applications should have (adaptive) jitter buffers
in this day and age, right?
-- 
Simon.