[nsp] How to adjust the "traffic share count/ratio" of equal cost IGP path ?

From: Yu Ning (yuning@ns.chinanet.cn.net)
Date: Mon Sep 25 2000 - 03:21:21 EDT


Hi All,

We know that if we see equal cost IGP routes, the Cisco box will load balance between
the different output interfaces. For example:

Routing entry for 202.97.9.60/30
  Known via "isis", distance 115, metric 5, type level-2
  Redistributing via isis
  Last update from 202.97.10.173 on ATM4/1.1, 5d04h ago
  Routing Descriptor Blocks:
  * 202.97.9.17, from 202.97.9.17, via POS2/0
      Route metric is 5, traffic share count is 1
    202.97.9.161, from 202.97.9.161, via POS2/3
      Route metric is 5, traffic share count is 1
    202.97.10.173, from 202.97.10.173, via ATM4/1.1
      Route metric is 5, traffic share count is 1

The "*" sign indicate the current route used. But normally the traffic load will evenly
shared in all the parallel paths, no matter how different BW they are. Then I wonder if
there is any method to adjust the "traffic share count" of the different output interface,
so that I can get an uneven load share?

The possibility of this idea comes to me when I dig some document on cisco MPLS-TE, it says
that if two MPLS tunnels have different BW, the "traffic share count" will be adjusted according
to the bandwidth ratio automatically. Because the load share is based on the CEF, and is generic
to all kinds of IGP, then I think it maybe possible in ISIS.

Our environment is: GSR with dCEF enable, IOS 12.0 train. IGP=ISIS.

Any input? Thanks!


Yu Ning
-------------------------------------------
(Mr.) Yu(2) Ning(2)
ChinaNet Backbone Operation
Networking Dep.,Datacom Bureau
China Telecom.,Beijing,P.R.C
+86-10-66418105/66418121/66418122
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