[c-nsp] GRE throughput on 3750G

[Ramcharan, Vijay A]

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. 

Just a sanity check before I open a TAC case. 

Brief test output below was obtained using a pair of 3550 switches: 
Without GRE:
------------------------------------------
C:\>iperf -f m -s -p 333
------------------------------------------------------------
Server listening on TCP port 333
TCP window size: 0.01 MByte (default)
------------------------------------------------------------
[1752] local 172.16.0.2 port 333 connected with 172.16.1.2 port 1058
[ ID] Interval       Transfer     Bandwidth
[1752]  0.0-15.0 sec   165 MBytes  92.4 Mbits/sec


With GRE:
------------------------------------------
C:\>iperf -f m -s -p 333
------------------------------------------------------------
Server listening on TCP port 333
TCP window size: 0.01 MByte (default)
------------------------------------------------------------
[1752] local 172.16.0.2 port 333 connected with 172.16.1.2 port 1061
[ ID] Interval       Transfer     Bandwidth
[1752]  0.0-15.0 sec  23.7 MBytes  13.2 Mbits/sec
------------------------------------------------------------

Thanks much. 
 
Vijay Ramcharan