Dell PowerSwitch S4820T Configuration Guide for the S4820T System 9.100.0 - Page 174

Item Local preference MED Route Flap Damping Parameters Distance Timers Add-path Default 100 0 half-life = 15 minutes reuse = 750 suppress = 2000 max-suppress-time = 60 minutes external distance = 20 internal distance = 200 local distance = 200 keepalive = 60 seconds holdtime = 180 seconds Disabled Enabling BGP By default, BGP is not enabled on the system. Dell Networking OS supports one autonomous system (AS) and assigns the AS number (ASN). 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 is established, the neighbors exchange full BGP routing tables with incremental updates afterward. In addition, neighbors exchange KEEPALIVE messages to maintain the connection. In BGP, neighbor routers or peers can be classified as internal or external. External BGP peers must be connected physically to one another (unless you enable the EBGP multihop feature), while internal BGP peers do not need to be directly connected. The IP address of an EBGP neighbor is usually the IP address of the interface directly connected to the router. First, the BGP process determines if all internal BGP peers are reachable, then it determines which peers outside the AS are reachable. NOTE: Sample Configurations for enabling BGP routers are found at the end of this chapter. 1 Assign an AS number and enter ROUTER BGP mode. CONFIGURATION mode router bgp as-number • as-number: from 0 to 65535 (2 Byte) or from 1 to 4294967295 (4 Byte) or 0.1 to 65535.65535 (Dotted format). Only one AS is supported per system. NOTE: If you enter a 4-Byte AS number, 4-Byte AS support is enabled automatically. a Enable 4-Byte support for the BGP process. NOTE: This command is OPTIONAL. Enable if you want to use 4-Byte AS numbers or if you support AS4 number representation. CONFIG-ROUTER-BGP mode 174 Border Gateway Protocol IPv4 (BGPv4)