[c-nsp] bgp maximum-paths

[MrPaul]

Are you wanting to load balance inbound, outbound, or both?

Without knowing all the details the cleanest solution would be to split your
address space in half.  Then send one half to provider A and the other half
to provider B.  Also send the entire network block to both provider A & B
for backup purposes.  The only issue here is you need to hope that you have
enough address space to support this.  That way under normal circumstances
1/2 your IP space will come in provider A while the other half will come
provider B.

For outbound load balancing you'll probably need to take full routes and
then do something like prefer odd addresses out provider A and even out
provider B.  You may find that taking full routes will balance enough.
Typical customers don't bother load balancing outbound traffic as there
isn't much.

Paul

On Wed, Apr 14, 2010 at 4:26 PM, Chris Gotstein <chris at uplogon.com> wrote:

> Does this seem like a valid way to load balance?
>
> http://ccnalab.net/bgp-routing/bgp-load-sharing-2-isp/
>
> ---- ---- ---- ----
> Chris Gotstein, Sr Network Engineer, UP Logon/Computer Connection UP
> http://uplogon.com | +1 906 774 4847 | chris at uplogon.com
>
> On 4/14/2010 4:23 PM, MrPaul wrote:
> > On Wed, Apr 14, 2010 at 3:03 PM, Chris Gotstein <chris at uplogon.com
> > <mailto:chris at uplogon.com>> wrote:
> >
> >     We are a multi-homed ISP with connections to 2 different providers
> (AS
> >     Numbers)  Does the bgp maximum-paths 2 command have any effect on
> load
> >     balancing between the 2 connections since they are different AS's or
> >     does that command only work when you have multiple paths to the same
> AS?
> >
> >
> > Taken from
> >
> http://www.cisco.com/en/US/tech/tk365/technologies_configuration_example09186a00800945bf.shtml
> >
> > By default, BGP chooses one best path among the possible equal-cost
> > paths that are learned from one AS. However, you can change the maximum
> > number of parallel equal-cost paths that are allowed. In order to make
> > this change, include the maximum-paths paths  command under the BGP
> > configuration. Use a number between 1 and 6 for the paths  argument.
> >
> > That feature is only of use if you are dual-homed to the same AS.
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