- Enterasys Security Router User's Guide

Overview
XSR User’s Guide 6-15
• Permit a local BGP speaker to send the default route 0.0.0.0 to a neighbor as the default route:
neighbor default-originate
• Configure the COMMUNITIES attribute to be sent to the neighbor at this IP address:
neighbor send-community
• Permit interior BGP sessions to use any working interface for TCP links: neighbor update-
source interface
• Permit BGP sessions, even when the neighbor is not on a directly connected segment:
neighbor ebgp multihop
• Specify the minimum interval between BGP routing update transmissions: neighbor
advertisement-interval seconds
• Configure MD5 authentication on a TCP link to a BGP peer: neighbor password <value>.
For an example, refer to “TCP MD5 Authentication for BGP Example” on page 6-25.
• Specify BGP routing updates to/from neighbors, as detailed in an ACL:
neighbor
distribute-list {ACL#}{in | out}
• Set up a BGP filter: neighbor filter-list ACL# {in | out}
• Disable next-hop processing on BGP updates to a neighbor: neighbor next-hop-self
• Assign a route map to in or outbound routes: neighbor route-map map-# {in | out}
• Set the XSR to begin storing received updates: neighbor soft-reconfiguration inbound
• Disable a BGP neighbor or peer group: neighbor shutdown. Conversely, you can enable a
previously existing neighbor or neighbor peer group that was disabled with
no neighbor
shutdown
For configuration examples, refer to “Configuring BGP Peer Groups” on page 6-25.
Initial BGP Configuration
Begin BGP configuration by enabling BGP routing:
• Enable a BGP Routing process and acquire Router Configuration mode: router bgp <AS #>
• Mark a “local” network in this AS, adding it as an entry in the BGP Routing table: network
<IP address> mask <subnet>
Adding BGP Neighbors
Adding neighbors to a BGP network is fundamental to building a BGP environment. You can add
internal neighbors (those inside an AS) or external neighbors (those in other AS’s). Usually,
external neighbors are next to each other and share a subnet while internal neighbors may be
situated anywhere in the same AS. The process on the XSR is as follows:
• Add a BGP network: network <IP address> mask <mask>
• Add a BGP neighbor: neighbor <IP address> remote-as <as #>
For an example, refer to “Configuring BGP Neighbors” on page 6-23.
Resetting BGP Connections
If you alter any BGP configuration values that you have defined for BGP neighbors, you must
reset that BGP connections for the configuration change to take effect.
• Reset one or more BGP connections: clear ip bgp address