Reference Guide

212 | Border Gateway Protocol IPv4 (BGPv4)
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Figure 9-26. Command example: show ip bgp paths
AS-PATH ACLs use regular expressions to search AS_PATH values. AS-PATH ACLs have an “implicit
deny.” This means that routes that do not meet a deny or match filter are dropped.
Use these commands in the following sequence, starting in the CONFIGURATION mode to configure an
AS-PATH ACL to filter a specific AS_PATH value.
Step Command Syntax Command Mode Purpose
1
ip as-path access-list
as-path-name
CONFIGURATION Assign a name to a AS-PATH ACL and enter AS-PATH
ACL mode.
2
{deny | permit} filter
parameter
CONFIG-AS-PATH Enter the parameter to match BGP AS-PATH for
filtering. This is the filter that will be used to match the
AS-path. The entries can be any format, letters,
numbers, or regular expressions.
This command can be entered multiple times if multiple
filters are desired.
Refer to Table 9-4 for accepted expressions.
3
exit
AS-PATH ACL Return to CONFIGURATION mode
Dell#show ip bgp paths
Total 30655 Paths
Address Hash Refcount Metric Path
0x4014154 0 3 18508 701 3549 19421 i
0x4013914 0 3 18508 701 7018 14990 i
0x5166d6c 0 3 18508 209 4637 1221 9249 9249 i
0x5e62df4 0 2 18508 701 17302 i
0x3a1814c 0 26 18508 209 22291 i
0x567ea9c 0 75 18508 209 3356 2529 i
0x6cc1294 0 2 18508 209 1239 19265 i
0x6cc18d4 0 1 18508 701 2914 4713 17935 i
0x5982e44 0 162 18508 209 i
0x67d4a14 0 2 18508 701 19878 ?
0x559972c 0 31 18508 209 18756 i
0x59cd3b4 0 2 18508 209 7018 15227 i
0x7128114 0 10 18508 209 3356 13845 i
0x536a914 0 3 18508 209 701 6347 7781 i
0x2ffe884 0 1 18508 701 3561 9116 21350 i
0x2ff7284 0 99 18508 701 1239 577 855 ?
0x2ff7ec4 0 4 18508 209 3561 4755 17426 i
0x2ff8544 0 3 18508 701 5743 2648 i
0x736c144 0 1 18508 701 209 568 721 1494 i
0x3b8d224 0 10 18508 209 701 2019 i