[nsp] Question about Committed Access Rate

From: Ritu Chadha (chadha@research.telcordia.com)
Date: Fri Jul 28 2000 - 16:04:07 EDT


Quick question about CAR on Cisco routers:
Suppose a customer marks packets with precedence levels
0,1,2. Suppose the customer router is configured as follows
using CAR:

Police outgoing traffic with precedence 0 at 0.4 Mbps, drop excess traffic
Police outgoing traffic with precedence 1 at 0.5 Mbps, drop excess traffic
Police outgoing traffic with precedence 2 at 1.0 Mbps, drop excess traffic
Police overall outgoing traffic at 1.5Mbps.

My question is: first of all, is the above config allowed (because
the total bandwidth specified for precedence classes 0, 1, and 2
is 0.4+0.5+1=1.9Mbps, whereas the overall allowed bandwidth is
only 1.5Mbps)? And secondly, if it is allowed, what would happen
if the customer sends traffic with precedence markings of 0,1, and 2
at the rates of 0.4, 0.5, and 1.0 respectively - what gets dropped?
(I assume that some of this traffic gets dropped because it
exceeds the overall limit of 1.5M).
Is there going to be loss for all three classes of service?

Thanks
Ritu



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