Administrator Guide

To configure an AS-PATH ACL to filter a specific AS_PATH value, use these commands in the following sequence.
1. Assign a name to a AS-PATH ACL and enter AS-PATH ACL mode.
CONFIGURATION mode
ip as-path access-list as-path-name
2. Enter the parameter to match BGP AS-PATH for filtering.
CONFIG-AS-PATH mode
{deny | permit} filter parameter
This is the filter that is used to match the AS-path. The entries can be any format, letters, numbers, or regular expressions.
You can enter this command multiple times if multiple filters are desired.
For accepted expressions, refer to Regular Expressions as Filters.
3. Return to CONFIGURATION mode.
AS-PATH ACL mode
exit
4. Enter ROUTER BGP mode.
CONFIGURATION mode
router bgp as-number
5. Use a configured AS-PATH ACL for route filtering and manipulation.
CONFIG-ROUTER-BGP mode
neighbor {ip-address | ipv6-address | peer-group-name} filter-list as-path-name {in |
out}
If you assign an non-existent or empty AS-PATH ACL, the software allows all routes.
To view all BGP path attributes in the BGP database, use the show ip bgp paths command in EXEC Privilege mode.
DellEMC#show ip bgp paths
Total 386 Paths
Refcount Metric Path
20 0 64801 i
20 0 64801 i
20 0 64801 i
20 0 64801 i
20 0 64801 i
20 0 64801 i
20 0 64801 i
20 0 64801 i
20 0 64801 i
20 0 64801 i
20 0 64801 i
20 0 64801 i
20 0 64801 i
20 0 64801 i
20 0 64801 i
20 0 64801 i
20 0 64801 i
20 0 64801 i
20 0 64801 i
20 0 64801 i
20 0 64801 i
--More--
Filtering Routes with Community Lists
To use an IP community list or IP extended community list to filter routes, you must apply a match community filter to a route
map and then apply that route map to a BGP neighbor or peer group.
1. Enter the ROUTE-MAP mode and assign a name to a route map.
CONFIGURATION mode
route-map map-name [permit | deny] [sequence-number]
2. Configure a match filter for all routes meeting the criteria in the IP community or IP extended community list.
198
Border Gateway Protocol (BGP)