Outbound Route Optimization

Wed Jan 21 21:28:21 UTC 2004

> > ... depends on your isp, and whether their routing policies (openness
> > or closedness of peering, shortest vs. longest exit, respect for MEDs)
> > are a good match for their technology/tools, skills/experience, and
> > resources/headroom.
> 
> In practice, all of the above just turn out to be marketing sauce
> or in some cases, outright lies.

well, sometimes.  if someone claims to do longest exit but is buying a
congested L2-in-L2 or L2-in-L3 pipe from someone else to do "remote
peering" in order to avoid spend, then they lied.  on the other hand
if someone spends like hell on their core infrastructure but then runs
RIPv2 as their igp and doesn't peer except in three places worldwide
then all the money in the world won't help their measured performance.

> There is no substitute for dollar spend (opex and capex) to make
> a network perform.  There is no magic sauce, there is no silver
> bullet. You have adequate resources, you will have adequate
> performance.

see above, i mostly agree but there have been counterexamples.

> > metrics, which is usually not very good.  but there's another limit,
> > which is bgp path symmetry.  most tcp implementations are still
> > stone-aged
> 
> AKA optimizing for outbound doesn't do you any good on optimizing
> for inbound.

more to the point, even if you have an outbound-heavy customer base, your
inbound quality still going to have an impact on your output quality, and
your inbound quality is generally unaffected by spend alone.

> > (experience says they're not going to trust your MEDs even if
> > they're close enough to hear them.)
> 
> Most people don't trust MEDs for a reason paul, and it is not because
> they want to mess with your customers.

whoa there big guy.  i didn't say, either in the part you quoted or in
the part you didn't quote, that not listening to med's was evil intentioned.
not that it matters.  intentions are irrelevant, the fact is that there
aren't a lot of ways to control the routing decisions made by others.  the
most you can do is give other networks more opportunities to shortest-exit
onto your network where you, if you've spent enough, can make things like
quality and symmetry happen.