Need Help with v7 ROS BGP multihome failover

RouterOS Forwarding Protocols
1

Hi Friends,

I have recently moved from ROSv6 to ROSv7. I am completely lost n the BGP configuration here. I have two ISPs and want to peer with both but preferring one as the active while the other the passive. I have two subnets, let’s say 172.16.11.0/24 and 172.16.12.0/24 and need to receive full route from both. I will want ISP A to be active and ISP B to be failover. I need help in the following

  1. To create a routing filter in the in and out directions for both ISPs specifying path to/from A as preferred.
  2. How to not be a transit ASN for both ISPs

Thanks in advance.

2

Hi Friends, any help? Please..

3

It sounds like you had already settled on a routing policy under ROS v6. Can we see your existing configuration (with any sensitive bits removed)?

4

Hi,

Assuming you are doing two bgp feeds on a single router, you may use WEIGHT attribute.

On your incoming filter for your primary feed set BGP WEIGHT to something like 10, as long as this is higher than the other feed it will be marked as primary
Then on the outgoing filter of your secondary prepend your own AS 3 times.

This will give you a failover that if one bgp peer or its link goes down the routes will disappear from the routing table and then the other routes will become active. This is not a very fast process (maybe as much as 180seconds).

If your BGP upstreams allow you could try BFD to make failover detection faster. BFD is v new in Routeros 7, so your mileage may vary.

Alex