09-05-2008 05:41 AM
Hi, Very new to Junos and BGP
I have two routers a J2300 and J2320, I documentation on how to setup VRRP on the routers for the Lan side. However I have a 1.5 meg MPLS connection on one a 3 meg on the other. I'm running BGP on the Wan side. How can I setup my BGP to ensure that the 3meg connection is the primary and the 1.5 is used only as a backup in case of failure while running VRRP between the two routers?
09-08-2008 12:00 PM
This should be relatively straightforward for you. If you wish to prefer the 3M link absolutely (i.e. *no* traffic will traverse the 1.5M link unless the 3M link is dead) then you can do the following...
1. On receipt of prefixes from your neighbour over the 3M link, set the LOCALPREF of the prefixes to 120.
2. On receipt of prefixes from your neighbour over the 1.5M link, set the LOCALPREF of the prefixes to 80. You could leave it at the default value of 100, but this is simply a step designed to demonstrate that if you raise the LOCALPREF, the prefix is preferred; if you decrease it, the prefix becomes less preferred.
3. Make sure that you run iBGP between the two routers.
4. Configure VRRP on the two LAN interfaces. On the router with the 3M link set the priority to 200, on the router with the 1.5M link, set the priority to 150. On the router with the 3M link, configure it to track the 3M link with a link cost of 100. Therefore, the router with the 3M link becomes the VRRP master. If the 3M link dies, the priority of that router becomes 100 (200-100) which is less than the 150 of the other router so mastership switches.
I hope that helps.