regular expression _154$ and ^154$ ?

zillah

Requirement :
Part of the acquisition agreement between AS 300 and AS 200 includes stipulations on what traffic AS 300 will provide transit for.

This agreement states that AS 300 will not provide transit for traffic coming from AS 60 and its customers, that is destined for AS 154. Configure AS 300 to reflect this policy


Configuration:
router bgp 300
neighbor 204.12.1.154 route-map STOP_TRANSIT_TO_AS_154 out
!
ip as-path access-list 5 permit _154$
!
route-map STOP_TRANSIT_TO_AS_154 deny 20
match as-path 5
!
route-map STOP_TRANSIT_TO_AS_154 permit 30

In the configuration above ,can we configure regular expression _154$ as ^154$ ?

Ten9t6

you have to watch what you want to allow:

_154$ ... matches routes originating from AS 154 and ones that are prepended with 154

^154$ ...matches all routes that start and end with AS 154....no prepending.

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on a side note, which test are you studying for? Yesterday, you had switching questions....now Regular Expressions for AS Path filtering...(BGP).... I am just curious. Talk to you later...

Kenny