Administrator Guide

{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 | 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.
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
0x5eb1e44 0 1 18508 701 8584 16158 i
0x5cd891c 0 9 18508 209 6453 4759 i
--More--
Regular Expressions as Filters
Regular expressions are used to filter AS paths or community lists. A regular expression is a special character used to define a
pattern that is then compared with an input string.
For an AS-path access list, as shown in the previous commands, if the AS path matches the regular expression in the access list,
the route matches the access list.
The following lists the regular expressions accepted in the Dell Networking OS.
Regular
Expression
Definition
^ (caret) Matches the beginning of the input string. Alternatively, when used as the first character within brackets
[^ ], this matches any number except the ones specified within the brackets.
$ (dollar) Matches the end of the input string.
. (period) Matches any single character, including white space.
Border Gateway Protocol IPv4 (BGPv4) 191