Load Balancing Multiple DS3s (outgoing) on a 7500

Sun Mar 14 00:19:40 UTC 2004

On Fri, Mar 12, 2004 at 11:37:25PM -0500, Joe Abley wrote:
> On 12 Mar 2004, at 23:24, joe mcguckin wrote:
> 
> > I suspect that each FE goes to a different AS...
> 
> In that case, sample/count outbound traffic volumes by 
> (prefix/AS/AS_PATH/something), sort the resulting list, and develop an 
> import policy based on the top N entries which shares the traffic by 
> tweaking some other attribute to avoid the last-resort tie-break.

The tool "ehnt" is pretty useful for generating a "top" style list of
ASes in order of the amount of traffic you're sending their way.

By the way, w/r/t to the tiebreaker stuff, note that (on Cisco devices)
if you don't have "bgp bestpath compare-routerid" set, the route that
was received first will be preferred. This minimizes route-flap, but can
cause weird shifts in your traffic patterns when one bgp session or
another goes down (credit goes to Mark Nagel for figuring out this one
for me).

-- 
"Since when is skepticism un-American?
Dissent's not treason but they talk like it's the same..."
(Sleater-Kinney - "Combat Rock")