why bgp specific routes needed.

[rittam bhattacharya]

Hello Guys,

In my core routers in backbone I am only finding default routes for Internet , but in Internet gateway router all the public IPs are there along-with the default route. If I am advertising only default route to my Backbone (Internally) from this gateway router then why I have asked the ISP for the all public pools ? I could have asked for default route only, isn't it ?

[Vinit Jain]

Hello Rittam

there are multiple ways you can have reachability towards the Internet. You can either use a default route or use the Internet Routing Table. Usually, the Internet routing table is used by the provider or small providers) to further provide share those routes with other customers who are looking for those routes. Any decent ISP will give you the choice of full, partial and default routes.

So, if you are looking for saving some resources on your device, you may check with your provider and your design team if default route is an option unless Internet table is absolute necessary.

But, i would also like to make you aware if the default route is propagated in an improper way or there are multiple default routes configured within your network can lead to loop conditions.

Hope this helps.

Regards

Vinit

[t.tineo]

Rittam,

With almost 600,000 internet routes one must be careful where these are advertised. The router accepting these many prefixes must have enough memory to handle the load. 

To answer your question, yes you could get away with just getting a default route from your ISP, especially if you have a single internet router.