How to Verify Bandwidth on an LSP Using Junos

By Walter J. Goralski, Cathy Gadecki, Michael Bushong

It’s important to check that your RSVP-signaled LSP has the appropriate bandwidth allocation. How can you tell that your RSVP-signaled LSP has the appropriate bandwidth allocation? If you want to look at the characteristics, you use the show rsvp interface command:

user@router1> show rsvp interface 
RSVP interface: 4 active 
                  Active Subscr- Static      Available   Reserved   Highwater 
Interface   State resv   iption  BW          BW          BW         mark 
fe-0/0/0.0  Up         2   100%  155.52Mbps  155.52Mbps  50Mbps     0bps 
fe-0/0/1.0  Up         0   100%  155.52Mbps  155.52Mbps  0bps       0bps 
fe-1/0/1.0  Up         0   100%  155.52Mbps  155.52Mbps  0bps       0bps 

In this example, router 1 has three interfaces with RSVP enabled. When you look at the reserved bandwidth on the router, you need to know what bandwidth reservation really means. If you have umpteen flows through a particular interface, what you really want to do is limit some or all of those flows to a specific piece of the overall capacity on the link.

So when you look at RSVP sessions and the bandwidth tied to them, what you’re seeing with the show rsvp interface command is the total sum of all allocated bandwidth on all the LSPs for which this router is an LSR.

The totals can be extremely helpful in ensuring that your allocated bandwidth is in line with what you want it to be. If the allocated bandwidth exceeds 100 percent, the LSPs with a reserved bandwidth specified won’t use that router as a transit router.