[nsp] Load sharing over unequal bandwidth lines using CEF

[Harold Ritter]

Earl,

This is not CEF but routing protocol related. To do unequal cost path load 
balancing you need a routing protocol that supports it. Currently, Eigrp 
and BGP (Link bandwidth feature) support it.

At 08:06 AM 6/2/2003 -0400, Earl Zmijewski wrote:

>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 
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Harold Ritter, CCIE 4168
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