Routing issues

[Martin Barry]

$quoted_author = "dspazman at epicup.com" ;
> 
> Would cause the path through the connection on eth0 to be 10x more
> prefered then the path through eth1, so incoming bandwidth should be split
> in about a 10-1 ratio.  So if I have eth0 as a 10 Gig connection, and eth1
> as a 1 Gig connection, between using that for incoming traffic, and a
> multipath rule for outgoing traffic like this:
> 
> ip route add default scope global nexthop via 1.1.1.153 dev eth0 weight 10 nexthop via 2.2.2.81 dev eth1 weight 1
> 
> Would cause the two connections to be pretty uniformly used on incoming
> and outgoing traffic at a 10/1 ratio, allowing me to pretty fully saturate
> both lines?

Like the other Martin said, this doesn't work quite how you are thinking.

BGP unfortunately has only a limited range of controls one can manipulate
and often you have no control over what remote ASes are doing and hence
can't control the inbound traffic as much as you would like (if at all).

You'll need to read up more on the BGP selection criteria and how these work
but the ones to focus on for...

Inbound
- prefix specificity
- AS path and prepending thereof
- Communities. Signals to your upstreams for things like 'no export' or
  prepending to specific ASes
- MED. This is works best with multiple links to the same provider.

Outbound
- filtering
- local preference


cheers
Marty