Chapter 12: BGP Configuration Guide126 SmartSwitch Router User Reference ManualThe SSR BGP ImplementationThe SSR routing protocol implementation is based on GateD 4.0.3 code(http://www.gated.org). GateD is a modular software program consisting of coreservices, a routing database, and protocol modules supporting multiple routing protocols(RIP versions 1 and 2, OSPF version 2, BGP version 2 through 4, and Integrated IS-IS).Since the SSR IP routing code is based upon GateD, BGP can also be configured using aGateD configuration file (gated.conf) instead of the SSR Command Line Interface (CLI).Additionally, even if the SSR is configured using the CLI, the gated.conf equivalent can bedisplayed by entering the ip-router show configuration-file command at the SSR Enableprompt.VLANs, interfaces, ACLs, and many other SSR configurable entities and functionality canonly be configured using the SSR CLI. Therefore, a gated.conf file is dependent upon someSSR CLI configuration.Basic BGP TasksThis section describes the basic tasks necessary to configure BGP on the SSR. Due to theabstract nature of BGP, many BGP designs can be extremely complex. For any one BGPdesign challenge, there may only be one solution out of many that is relevant to commonpractice.When designing a BGP configuration, it may be prudent to refer to information in RFCs,Internet drafts, and books about BGP. Some BGP designs may also require the aid of anexperienced BGP network consultant.Basic BGP configuration involves the following tasks:• Setting the autonomous system number• Setting the router ID• Creating a BGP peer group• Adding and removing a BGP peer host• Starting BGP• Using AS path regular expressions• Using AS path prepend
