append-bgp-communities and 32 bit ASN

RouterOS Forwarding Protocols
1

Hi.
How can i mark prefixes from one ISP like AS1111 and make community like in code ?
Is there any other chance to do it ?

routing filter set 31 append-bgp-communities=198408:1000
value of as out of range (0..65535)
2

What you are looking for are BGP Extended Communities as defined in:

http://www.ietf.org/rfc/rfc4360.txt

In RouterOS this is implemented via route targets and applied to a route filter:
/routing filter
add action=accept chain=BGP-OUT set-route-targets=198408:1000

3

Ok , but i have for example 10 peers, and prefixes from one peer , a want to send for my client router, who establish session with my router, or for example prefixes from 2 peers. I want to transit some prefixes for my client.

Someone can show example config ?

4

I’m not entirely sure I understand what you’re asking - do you mean you want to become a transit AS between two or more of your peers?

5

Yes.

6

It’s pretty easy actually, just advertise the networks and subnets that you want the customer/peer to learn from you. This can all be controlled with a route filter applied to the peer in the outbound direction.

For example if you want a peer to learn the path only for the following /24 prefixes, then use a config like this:
add name=peer1 out-filter=BGP-OUT remote-address=10.1.1.2 remote-as=1111 ttl=
default
/routing filter
add action=accept chain=BGP-OUT prefix=100.64.0.0/24
add action=accept chain=BGP-OUT prefix=100.64.20.0/24
add action=accept chain=BGP-OUT prefix=100.64.10.0/24
add action=discard chain=BGP-OUT

7

Ok , i understand.

I’w tested this options and they are ok, in /router bgp adrv i see prefixes advertised to peer, but when i look on LG of this peer, there is still 1 prefix.

8

If you have verified the prefixes are being advertised to the peer, then you need to validate the route filters of the peer and see why the prefixes you expect to see are being blocked.

9

As far as MPLS mtu goes, here are the numbers you need for 1500 bytes frames.

1526 - To run untagged VPLS
1530 - To run tagged VPLS

As far as PPPoE, it requires 8 bytes of overhead for the PPP portion.