Dell PowerSwitch S5212F-ON EMC SmartFabric OS10 User Guide Release 10.5.0 - Page 560

• Prepend 65001 65002 to AS-PATH. Local-AS prepends before the route map to give the appearance that the update passed through a router in AS 200 before it reaches Router B. Graceful restart OS10 offers graceful restart capability for BGP in helper mode only. A BGP router whose neighbor is restarting is called a "helper." If graceful restart is enabled on the restarting router, during restart, the helper maintains the routes that it has learned from its neighbor. After the switch over, the graceful restart operation begins. Both routers reestablish their neighbor relationship and exchange their BGP routes again. The helper continues to forward prefixes pointing to the restarting peer, and the restarting router continues to forward traffic to its peers even though those neighbor relationships are restarting. When the restarting router receives all route updates from all BGP peers that are graceful restart capable, the graceful restart is complete. BGP sessions become operational again. Configure Border Gateway Protocol BGP is disabled by default. To enable the BGP process and start to exchange information, assign an AS number and use commands in ROUTER-BGP mode to configure a BGP neighbor. BGP neighbor All BGP neighbor changes are logged adjacency changes Fast external fallover Enabled Graceful restart Disabled Local preference 100 4-byte AS Enabled MED 0 Route flap dampening parameters • half-life = 15 minutes • max-suppress-time = 60 minutes • reuse = 750 • suppress = 2000 Timers • keepalive = 60 seconds • holdtime = 180 seconds Add-path Disabled Enable BGP Before enabling BGP, assign a BGP router ID to the switch using the following command: • In the ROUTER BGP mode, enter the router-id ip-address command. Where in, ip-address is the IP address corresponding to a configured L3 interface (physical, loopback, or LAG). BGP is disabled by default. The system supports one AS number - you must assign an AS number to your device. To establish BGP sessions and route traffic, configure at least one BGP neighbor or peer. In BGP, routers with an established TCP connection are called neighbors or peers. After a connection establishes, the neighbors exchange full BGP routing tables with incremental updates afterward. Neighbors also exchange the KEEPALIVE messages to maintain the connection. You can classify BGP neighbor routers or peers as internal or external. Connect EBGP peers directly, unless you enable EBGP multihop - IBGP peers do not need direct connection. The IP address of an EBGP neighbor is usually the IP address of the interface directly connected to the router. The BGP process first determines if all internal BGP peers are reachable, then it determines which peers outside the AS are reachable. 560 Layer 3