D-Link DGS-6600-48TS Configuration Guide - Page 315

Volume 4-Layer 3 Configurations / Chapter 30-Border Gateway Protocol (BGP) BGP Configuration commands Configuring the BGP Origin Code Use the set origin command to set the BGP origin code. Use the route-map global configuration command, and the match and set route-map configuration commands, to define the conditions for redistributing routes from one routing protocol into another. Each route-map command has a list of match and set commands associated with it. The match commands specify the match criteria-the conditions under which redistribution is allowed for the current route-map command. The set commands specify the set actions-the particular redistribution actions to perform if the criteria enforced by the match commands are met. The no route-map command deletes the route map. The set route-map configuration commands specify the redistribution set actions to be performed when all of the match criteria of a route map are met. When all match criteria are met, all set actions are performed. The origin code (ORIGIN) is a well-known mandatory attribute that indicates the origin of the prefix or, rather, the way in which the prefix was injected into BGP. There are three origin codes, listed in order of preference: • IGP: Means that the prefix originated from information learned from an interior gateway protocol. • EGP: Means that the prefix originated from an exterior gateway protocol, which BGP replaced. • INCOMPLETE: Means that the prefix originated from an unknown source. Command enable {privilege LEVEL} configure terminal route-map MAP-NAME {permit | deny} SEQUENCE-NUM Explanation Enter privileged EXEC mode. Enter global configuration mode Enter this command to enter route-map configuration mode match aspath AS-PATH-LIST set origin {igp | egp | incomplete} Enter the following command to match a BGP autonomous system path to an access-list Enter the following command to set the BGP origin Configuration Example To set the origin of routes that pass the route map named myPolicy and match the AS path PATH_ACL to EGP: dgs-6600:2>enable dgs-6600:15#configure terminal dgs-6600:15(config)#route-map myPolicy permit 1 dgs-6600:15(config-route-map)#match as-path PATH_ACL dgs-6600:15(config-route-map)#set origin egp dgs-6600:15(config-route-map)# BGP Synchronization Usually, a BGP speaker does not advertise a route to an external neighbor unless that route is local or exists in the IGP. By default, synchronization between BGP and the IGP is turned off to allow the switch to advertise a network route without waiting for route validation from the IGP. This feature allows routers and access servers within an autonomous system to have the route before BGP makes it available to other autonomous systems. Command enable [privilege LEVEL] DGS-6600 Configuration Guide Explanation Enter privileged EXEC mode. 315