[c-nsp] GRE throughput on 3750G

Seth Mattinen sethm at rollernet.us
Mon Mar 23 12:56:04 EDT 2009


Ramcharan, Vijay A wrote:
> All, 
> I'm just looking for confirmation that GRE on the 3750G is done in
> software with the resulting low throughput (~20Mbps with iperf across
> GRE tunnel on 3750G). All testing and reading that I've done indicates
> that the hardware on the 3750 is not especially built for
> "router-specific" features like GRE. A "show int stats" shows that all
> packets on the tunnel interface in a pair of 3750G switches is process
> switched. The same command on a 3845 shows the majority of the traffic
> is hardware switched/forwarded. 
> 

3845 is still a software platform (with hardware crypto), but the CPU is
much faster. 3750 routes in hardware, however, its CPU is much slower if
you start doing stuff not supported in hardware.

~Seth


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