[c-nsp] Traffic Engineering Internet links automatically

[Pete Templin]

Kim Onnel wrote:
> 
> We have multiple OC3 links all terminated on one router, our initial
> configuration divided the networks according to their groups, e.g: ADSL on
> the first, SDSL on the 2nd.
> 
> Now that we have them all filled most of the time and the grouping wont
> work, we almost daily need to check MRTG, see which link has a few Mbits
> left and fill it by moving some networks, i am sure there is a much more
> civilized way to do it, any suggestions ?

(Jumping ahead by noting that you clarified your congestion to be inbound)

I'd say your better bet is to announce all networks on all pipes, then 
use BGP knobs (prepends on some prefixes, communities on some prefixes 
to influence upstream local preference and/or prepends, MEDs if you have 
multiple links to any one provider) to adjust your balance.  This can 
rapidly get time-consuming beyond much benefit (or even causing "damage" 
unless or until you have sufficient experience to guess the best 
adjustment on the first try).

As someone said on either this list or NANOG, his/her idea of sufficient 
capacity means any given link is no more than 50% full or has 50Mbps of 
open capacity on it.  I'd guess you're pushing your links too hard to be 
able to capture much more usage.  I normally reserve my tuning efforts 
for that lovely period between when I've ordered more bandwidth and when 
it's arrived; as soon as it arrives I try desperately to rip out any 
wild tunings to keep it simple, silly.  :)

pt