FTOS Configuration Guide for the C-Series - Force10 Networks

Use the following command in the CONFIGURATION ROUTER BGP mode to allow more than one path.
Command Syntax Command Mode Purpose
maximum-paths {ebgp | ibgp}
number
The show ip bgp network command includes multipath information for that network.
Filter BGP routes
CONFIG-ROUTER-
BGP
Filtering routes allows you to implement BGP policies. You can use either IP prefix lists, route maps,
AS-PATH ACLs or IP Community lists (via a route map) to control which routes are accepted and
advertised by the BGP neighbor or peer group. Prefix lists filter routes based on route and prefix length,
while AS-Path ACLs filter routes based on the Autonomous System number. Route maps can filter and set
conditions, change attributes, and assign update policies.
For inbound and outbound updates the order of preference is:
• prefix lists (using neighbor distribute-list command)
• AS-PATH ACLs (using neighbor filter-list command)
• route maps (using neighbor route-map command)
Enable multiple parallel paths.
• number range: 1 to 16
• Default is 1
Note: FTOS supports up to 255 characters in a set community statement inside a route map.
Note: With FTOS, you can create inbound and outbound policies. Each of the commands used for
filtering, has in and out parameters that must be applied. In FTOS, the order of preference varies
depending on whether the attributes are applied for inbound updates or outbound updates.
Prior to filtering BGP routes, you must create the prefix list, AS-PATH ACL, or route map to be used.
Refer to Chapter 17, IP Access Control Lists, Prefix Lists, and Route-maps, on page 333for configuration
information on prefix lists, AS-PATH ACLs, and route maps.
Note: When you configure a new set of BGP policies, always reset the neighbor or peer group by
entering the clear ip bgp command in EXEC Privilege mode.
Use these commands in the following sequence, starting in the CONFIGURATION mode to filter routes
using prefix lists.
Step Command Syntax Command Mode Purpose
1 ip prefix-list prefix-name CONFIGURATION Create a prefix list and assign it a name.
FTOS Configuration Guide, version 7.7.1.0 503