One important point to remember about iBGP relationships is that iBGP assumes that all of the routers within a single AS are fully meshed. That is, each router is peered to every other router within the same AS. The purpose of this is namely to fix any issues around loop prevention. You’ll recall the BGP […]
Archive for the ‘BGP’ Category
The BGP Best Path Algorithm determines how the best path to an autonomous system is selected. The most common value that is used to determine the best path is the AS Path length. When two or more routes exist to reach a particular prefix the default in BGP is to prefer the route with the […]
Cisco IOS prefix lists work similar access lists for route advertisements (prefixes). While extended, and to a limited extent, standard access lists can be configured to match prefix announcements, prefix lists are far more powerful. Like an access lists; a prefix list contains one or more ordered entries which are processed sequentially. As with access […]
In this Free CCNP GNS3 Lab we are going to use GNS3 to create simple BGP network consisting of four Cisco routers and a single switch to demonstrate how we can use BGP’s weight attribute to influence routing out of an autonomous system (AS).