RouterOS bgp-as-path filter

RouterOS Forwarding Protocols
1

I am trying to add a BGP filter to set a local preference to a specific AS.

Initially I just used prefix filters and it has worked fine, however for some bigger networks it seems wiser to filter via an AS, less typing, less updating.

prefix filter:

chain=ibgp-mt1-out prefix=66.102.0.0/20 invert-match=no prefix-length=20-32
     action=passthrough set-bgp-local-pref=200 set-bgp-prepend-path=""

So instead of using prefix filters like above, I have made a new one for an AS like this:

as-path filter:

chain=ibgp-mt1-out bgp-as-path=",15619\$" invert-match=no 
         action=passthrough set-bgp-local-pref=200 set-bgp-prepend-path=""

I have verified that the regexp is correct by typing:

/ip route print detail where bgp-as-path ~ ",15619\$"

which returns routes whose destination is AS15619.

However, unlike the prefix filter, which takes at most a couple of minutes or so to update the routing table with the local preference I set, the as-path filter seems to have no effect at all. I don’t see any updates in the routing table eventhough a lot of time has elapsed and to me everything seems to be setup correctly.

I am wondering if anyone has been successful with an as-path bgp filter for RouterOS as I unfortunately cannot find many examples online.

Thank you.

2

try this: _15619$

3

Thank you. This worked. The important part was not to use quotation marks around the regexp.

Working filter:

chain=ibgp-mt1-out bgp-as-path=_15619$ invert-match=no 
         action=passthrough set-bgp-local-pref=200 set-bgp-prepend-path=""