Distribute Lists

Distribute Lists
Distribute lists can be used to filter inbound or outbound advertisements for a BGP session to a peer.
Distribute lists are an effective tool in deciding which routes the router will accept or send out.
Distribute lists rely on either a standard access list or an extended access list to decide which
routes to permit or deny. In order to create a distribute list, you need to follow the following process:
1. Decide the routes that need to be blocked from and/or accepted by the router.
2. Determine whether an inbound filter on the router or an outbound filter on another device
would be better to use.
3. Create an access list to deny the routes to be blocked and to permit the routes that need to
be advertised.
4. Add the distribute list to the appropriate BGP sessions.
The command you need to use to implement the distribute list is as follows:
neighbor peer-address distribute-list access-list-number [in | out]
peer-address - address of the BGP peer you want to apply the filter to.
access-list-number - the number of the access list you created for
the distribute list.
After taking a look at Figure 9.7, we will utilize a distribute list to filter a route. We will start
by going through the four steps previously mentioned.