From: Swan, Jay (jswan@sugf.com)
Date: Thu Mar 15 2007 - 13:20:17 ART
Hardware CEF is enabled by default on all layer 3 interfaces on the
3750, and it looks like there's no option other than "ip load-sharing
per-destination".
You might try doing a "no ip route-cache cef" and see if that works.
IIRC, I believe that in some switches this command doesn't actually do
anything--you can't actually turn off CEF. I don't know if the 3750 is
one of these or not.
One thing you might try is to send some packets that can't be hardware
switched--something with IP options (like ping with record route
enabled), for example. Keep your "no ip route-cache" and "no ip
route-cache cef" on the interface and see if your packets with IP
options are sent load-shared per-packet.
Jay
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
groupstudy email
Sent: Wednesday, March 14, 2007 8:55 PM
To: ccielab@groupstudy.com
Subject: Re: Process Switching vs. Fast Switching on 3750
I didn't see my question make the list so I am putting it out again.
Thanks,
Danny
On 3/14/07, groupstudy email <groupstudy@gmail.com> wrote:
>
> Hello Group,
>
> I have a question perhaps someone in the group can help with. I have
a
> 3750 switch that I am doing some testing on and I am seeing some
unexpected
> behaviour.
>
> I have two VLANs; one for r1 and one for r2. On the other side of
these
> routers, live a network that can be accessed via both routers.
>
> ___________
> | |
> R1 R2
> | |
> -------- --------
> | |
> Switch1
>
> On the switch (which has a VLAN interface configured for each router
VLAN)
> I have configured two static routes; one pointing to r1 and the other
to r2
> (equal cost routes).
>
> My understanding is that by default, fast switching is enabled on the
> switch so load balancing is happening on a per-destination basis.
This is
> what all documentation I am encountering is saying. I would like the
switch
> to load balance on a per-packet basis so I have configured "no ip
> route-cache" under both VLAN interfaces. After this I would expect to
see
> the asterisk in the "show ip route x.x.x.x x.x.x.x" command on the
switch
> moving between the two different paths that are configured. It is not
> moving. I would also expect to see traffic arriving on both router
> interfaces from the switch. I only see one router receiving this
traffic.
>
> Am I missing something in my config or is my understanding of this
> functionality incorrect?
>
> Any help would be greatly appreciated.
>
> Thanks!
>
> S. Rick
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