[c-nsp] RES: Outbound Load balancing using eBGP

[Keegan Holley]

On Thu, Dec 23, 2010 at 10:41 AM, Leonardo Gama Souza <
leonardo.souza at nec.com.br> wrote:

> Hi,
>
> There is an approach of matching on LSB from the prefixes' octets of the
> full routing table (even/odd) and increase local-preference for one
> provider.
>
> For example:
>
> access-list 1 permit 0.0.0.0 255.254.254.255
> access-list 2 permit 0.0.1.0 255.254.254.255
> access-list 3 permit 0.1.0.0 255.254.254.255
> access-list 4 permit 0.1.1.0 255.254.254.255
>
> route-map ISP1 permit 10
>  match ip address 1 2
>  set local-preference 120
> route-map ISP1 permit 20
>  match ip address 3 4
>  set local-preference 110
> route-map ISP1 permit 1000
>
> route-map ISP2 permit 10
>  match ip address 1 2
>  set local-preference 110
> route-map ISP2 permit 20
>  match ip address 3 4
>  set local-preference 120
> route-map ISP2 permit 1000
>
>
I don't think this would work very well on the actual internet.  For example
I can think of several large ISP's where most of  their aggregated IP space
would fall on the same link or wouldn't be touched at all.  For example AT&T
(12/9) and Level3 (4/8) among others.