[c-nsp] Erspan on 7600

Tim Stevenson tstevens at cisco.com
Wed Aug 11 11:29:39 EDT 2010


It most certainly is done in h/w - as I said, both encap & decap (ie 
source & dest sessions) are hw based. At the dest box, the FE strips 
off the GRE/ERSPAN  header & dumps the original packet on the SPAN dest port.

Note that certain misconfigurations can cause a punt, particularly on 
the ERSPAN destination box. I suggest carefully following the config 
guide for the proper configuration. One key point is configuring 
identical IPs and ERSPAN IDs on the source & destination sessions.

That can all be avoided by just pointing directly to the IP of a host 
w/wireshark etc that can decode the packets with the GRE/ERSPAN still on it.

Hope that helps,
Tim

At 01:02 AM 8/11/2010, Mikael Abrahamsson averred:

>On Wed, 11 Aug 2010, Phil Mayers wrote:
>
> > We've used ERSPAN on some truly phenomenal bitrates; it *is* done in
> > hardware.
>
>Sending ERSPAN is done in hw, I've done multigigabit ERSPAN.
>
>ERSPAN reception is not done in HW (at least not when I tested) and it
>killed the box when I tried :P
>
>--
>Mikael Abrahamsson    email: swmike at swm.pp.se
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Tim Stevenson, tstevens at cisco.com
Routing & Switching CCIE #5561
Distinguished Technical Marketing Engineer, Cisco Nexus 7000
Cisco - http://www.cisco.com
IP Phone: 408-526-6759
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