Re: BGP Multi-homing

Hi Olumayokun.
When you have two defaults, you need to look a layer below your edge.
Because if you have two defaults, you can perfectly load balance (note to
Johny: load-balance and load-share do not have different meanings in this
sense) using CEF mechanism, or even more balanced using per-packet load
sharing.

Say you have R1 to ISP1 and R2 to ISP2. R1 and R2 are your CPEs. So what do
you have a layer below? If you built your network according to guidelines,
you should have redundant connection to this provider edge module do the
distribution layer. So in a best design you'd have router/switches R3 and
R4, which connect with R1 and R2 in full mesh fasion (so in the end you'd
have R1+R2+R3+R4 full mesh). So if any packet from anywhere on the network
go to the internet and arrive at the distribution layer at R3 or R4, then it
will be load balanced. Because of full mesh, both R3 and R4 will have two
default routes - one from R1 and the other from R2, with the same cost. So
you will naturally CEF load balance, or you can go to the interface and type
in "ip load-sharing per-packet".

But all this relies on good network design.

So this would be one of the methods how to load balance on output using
default routes.

On Mon, Jul 6, 2009 at 5:03 PM, olumayokun fowowe <olumayokun_at_gmail.com>wrote:

> Hello all,
>
> I am multi-homing to the internet via two ISPs, and both of them are
> sending
> just default routes to me. I have two blocks of IPs that I am advertising
> to
> the internet. The challenge I am having is tweeking BGP so that traffic
> from
> a particular block use ISP1 while traffic from the other block of IP should
> use ISP2. I have been able to tweek inbound traffic from the internet but I
> am having issues with the outbound traffic because of the fact that Iam
> just
> receiving default routes from the providers. Does anyone have a solution
> for
> me?
>
> Thanks,
>
> Olumayokun
>
>
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