Filtering BGP routes

[Steven Williams]

Besides a route map, what other way can you prevent a BGP neighbor from placing a certain route into its route table that its neighbor is advertising?                  

[Harold Ritter]

Hi Steven,

You can use different type of filters directly on the given neighbor, such as prefix-list, filter-list (as-path filtering), distribute-list, etc. For a detailed list, please refer to the BGP documentation. Route-maps are more flexible though and more commonly used in the industry.

Regards

[blau grana]

Hello,

Just to add to Harold's post, route-maps are used when you want filter BGP routes and also modify some attributes of permited routes (local preference, weight,...).

If you want just filter routes, you can use just prefix-list or any other method which Harold mentioned, but be aware that each method is suited for something else and sometimes you can not do same thing with two different methods. for example: prefix-list can not match BGP route based on AS_PATH as as-path access list. 

Best Regards

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