Automated Advertisments to Uplinks

[corliantindia]

We are an ISP and we have further 3 uplinks. The routes are advertised through all the three links. In our network we are using communities to send to respective up links. The problem is, in case any of the link is down, we need to manually change the communities and advertised it through the other uplink.

Can you suggest an automated way, something like priority, if route x we are advertising through link 1 and it goes down then it automatically started getting advertised through link2.

Regards..

[ashok_boin]

Hi,

Not with communities, but i can suggest in another way. For eg assuming, your complete network block is "192.168.32.0/19". Then, i'll segment this into "192.168.32.0/21", "192.168.40.0/21", "192.168.48.0/21" and "192.168.56.0/21".

My Adv to ISP's like this...

To ISP-1

192.168.32.0/19, 192.168.32.0/21, 192.168.40.0/21

To ISP-2

192.168.32.0/19, 192.168.40.0/21(with AS-path prepend), 192.168.48.0/21

To ISP-3

192.168.32.0/19, 192.168.48.0/21(with AS-path prepend), 192.168.56.0/21

Like this, according to your customers,their application analysis and your uplink capacities, you can do variable supernettting and advertisements. So, that if one ISP-1 is down, that traffic can divert through other ISP-2 as outside world sees the next best longest prefix from ISP-2.

Note : Don't forget to advertise your aggregate route to all providers along with your subnets.

We are using the same and working fine without any manual intervention during outages of uplink/s.

Regards...

Ashok.