Monitoring BGP Routes with Matching AS Paths and AS-Path Access Lists
Purpose
Display all routes whose AS path matches the specified AS-path access list. Report whether the indirect next hop of a route is unreachable; if not, display the IGP cost to the indirect next hop.
The show ip bgp filter-list and show bgp ipv6 filter-list commands display similar information.
Action
To display all routes whose AS path matches the specified AS-path access list:
host1#show ip bgp filter-list 1 Local router ID 192.168.1.153, local AS 100 72080 paths, 72080 distinct prefixes (5189760 bytes used) 72080 paths selected for route table installation 21667 path attribute entries (2962828 bytes used) Prefix Next-hop MED CalPrf Weight AS-path > 6.0.0.0/8 10.5.0.48 100 100 11488 701 7018 7170 > 12.0.0.0/8 10.5.0.48 100 100 11488 701 1740 7018 > 12.1.248.0/24 10.5.0.48 100 100 11488 701 7018 13391 > 12.2.6.0/24 10.5.0.48 100 100 11488 701 7018 11101 > 12.2.7.0/24 10.5.0.48 100 100 11488 701 7018 11101 > 12.2.76.0/24 10.5.0.48 100 100 11488 701 7018 11812 > 12.2.99.0/24 10.5.0.48 100 100 11488 701 7018 10656 > 12.2.109.0/24 10.5.0.48 100 100 11488 701 7018 10656 > 12.2.169.0/24 10.5.0.48 100 100 11488 701 7018 11806 > 12.4.114.0/24 10.5.0.48 100 100 11488 701 7018 14065 > 12.4.119.0/24 10.5.0.48 100 100 11488 701 7018 14065 > 12.4.175.0/24 10.5.0.48 100 100 11488 701 7018 11895 > 12.4.196.0/22 10.5.0.48 100 100 11488 701 7018 12163 > 12.5.48.0/21 10.5.0.48 100 100 11488 701 7018 12163 > 12.5.164.0/24 10.5.0.48 100 100 11488 701 7018 11134 > 12.6.42.0/23 10.5.0.48 100 100 11488 701 7018 11090
Meaning
Table 1 lists the show ip bgp filter-list command output fields.
Table 1: show ip bgp filter-list Output Fields
Field Name | Field Description |
|---|---|
Local router ID | BGP router ID of the local router |
local AS | Local autonomous system number |
paths | Total number of routes stored in the BGP routing table. If several peers have advertised a route to the same prefix, all routes are included in this count. |
distinct prefixes | Number of routes to unique prefixes stored in the BGP routing table. If several peers have advertised a route to the same prefix, only the best route is included in this count. |
paths selected for route table installation | Number of routes in the BGP routing table that have been inserted into the IP routing table |
path attribute entries | Number of distinct path attributes stored in BGP's internal path attributes table. If BGP receives two routes for different prefixes but with identical path attributes, BGP will create only one entry in its internal path attribute table and share it between the two routes to conserve memory. |
Prefix | Prefix for the routing table entry |
Next hop IP address | IP address of the next router that is used when a packet is forwarded to the destination network |
MED | Multiexit discriminator for the route |
CalPrf | Calculated preference for the route |
Weight | Weight of the route |
AS path | Autonomous system path |
