Community discussions

MikroTik App
 
User avatar
sjwrick
Frequent Visitor
Frequent Visitor
Topic Author
Posts: 87
Joined: Tue Jul 25, 2006 10:12 pm

Filter out specific /30 subnets after /24 is already advertised

Wed Feb 15, 2023 4:51 am

I have a subnet I have advertised in bgp
/routing bgp network print

Flags: X - disabled 
 #   NETWORK              SYNCHRONIZE
 0   100.110.12.0/22      no         
I want to filter(?) out and not advertise 100.110.12.36/30

How would I do that? I have moved the client to a different Tower and am unable to change the client IP. Still need to route to it for a short while.

Rick
 
pe1chl
Forum Guru
Forum Guru
Posts: 10195
Joined: Mon Jun 08, 2015 12:09 pm

Re: Filter out specific /30 subnets after /24 is already advertised

Wed Feb 15, 2023 12:50 pm

Write an output route filter that discards your /30 networks, e.g.:
/routing filter rule
add action=discard chain=out prefix=100.110.12.0/22 prefix-length=23-32

Remember that when you later want to migrate to v7 you also need to have some "accept" rule so it is better to add that now:
add action=accept chain=out
(also note that synchronize=no is no longer supported in v7)
 
User avatar
sjwrick
Frequent Visitor
Frequent Visitor
Topic Author
Posts: 87
Joined: Tue Jul 25, 2006 10:12 pm

Re: Filter out specific /30 subnets after /24 is already advertised

Wed Feb 15, 2023 8:53 pm

Thanks! I will not be moving to ROS v7 for a bit.

Appreciate the help.

Rick

Who is online

Users browsing this forum: No registered users and 15 guests