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BGP - Partial / full table / default route etc

Hi all

can anyone tell me how and why the providers can set up partial route table, with default etc

how do they do it?

why do they do it ?

cheers

Carl

2 REPLIES
Hall of Fame Super Bronze

BGP - Partial / full table / default route etc

They do it with BGP filtering tools such as prefix-list, route-maps, communities, among others.

They do it because the customer may have equipment that can't support full internet routing table.

Hall of Fame Super Silver

Re: BGP - Partial / full table / default route etc

Hello Carl,

depending on the customer needs the ISP can provide:

- a single default route

- a default route and selected routes

- a full internet table

A full internet table provides to the customer the capability to take optimal routing decisions but it requires a powerful router in terms of cpu and memory. (a single full table is in the order of 400,000 routes)

A single default route requires minimal resources but it does not provide to the customer details to take optimal routing decisions ( the customer can use multiple default routes from different ISPs in load balancing).

A partial table is used for providing detailed routes for selected destinations.

These destinations can be: other customers of the ISP or other entities that have important traffic volumes exchanged with the local customer. In this way the customer can use most specific routes to selected destinations.

The generation of a default route can be performed per neighbor using neighbor ... default-originate at the ISP router, the leaking of selected routes is performed using route filters typically implemented with a route-map, no route filters is applied when sending the internet full table

Hope to help

Giuseppe

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