[nsp] Load sharing over unequal bandwidth lines using CEF

[Earl Zmijewski]

Hello.  I have what I thought would be a simple question, but can find
no reference to a solution.  Consider a single router with 4
equal-weight default routes out 4 interfaces.  The goal is to take
advantage of the bandwidth across all interfaces, but they vary in
bandwidth.  Using CEF will apparently randomly distribute all
source-destination pairs across all 4 paths, but without regard to
available bandwidth.  You can see that as follows where the load
distribution used by CEF is ...

Load distribution: 0 1 2 3 0 1 2 3 0 1 2 3 0 1 2 3 ,

all lines being treated equally.  Is it possible to weight this
distribution in a way that favors the higher bandwidth lines?  Or is
there another alternative?

Thanks in advance for any suggestion.
Earl

----

gw#show ip cef 1.2.3.4 internal
0.0.0.0/0, version 90217, attached, per-destination sharing
51032209 packets, 40384605152 bytes
  via Multilink1, 0 dependencies
    traffic share 1
    valid adjacency
  via Multilink2, 0 dependencies
    traffic share 1
    valid adjacency
  via Multilink3, 0 dependencies
    traffic share 1
    valid adjacency
  via Multilink4, 0 dependencies
    traffic share 1
    valid adjacency

  51032209 packets, 40384605152 bytes switched through the prefix
  tmstats: external 0 packets, 0 bytes
           internal 51032209 packets, 40384605152 bytes
  30 second output rate 998 Kbits/sec
  High water mark 0, low water mark 0, current trigger set on no NHRP
interface
  Load distribution: 0 1 2 3 0 1 2 3 0 1 2 3 0 1 2 3 (refcount 1)