[c-nsp] High CPU utilization on sup720 with GRE

[Samir Abidali]

I am using Different source IP address, I will try user a loopback interface as a change and see if that will work.

Appreciate your help Simon

Thank you

Best Regards
Samir Abid Ali
Core Network Manager
Gorannet ISP
Mobile:07703-587-625
Office:053 5111 000 ext. 1032

-----Original Message-----
From: Simon Lockhart [mailto:simon at slimey.org] 
Sent: Sunday, March 24, 2013 2:14 PM
To: Samir Abidali
Cc: cisco-nsp at puck.nether.net
Subject: Re: [c-nsp] High CPU utilization on sup720 with GRE

On Sun Mar 24, 2013 at 02:06:09PM +0300, Samir Abidali wrote:
> Can you somebody help me in understanding whey GRE tunnel Cisco
> WS-SUP720-3BXL , with two GRE tunnel configured will spike the cpur to 99%
> when the traffic goes beyond 30mbps.
> 
> According to documentation, the GRE is hardware accelerated, please note that
> the two tunnel interface has two different source interface ( SVI source ip
> address  )

It's important to use a different source interface for each Tunnel (we use
loopback interfaces per tunnel).

I'm doing over 1Gbps of GRE spread over multiple tunnels, and my CPU is running
at around 30%.

I'd probably start by looking at MTU - is this box having to do a lot of
fragmentation? That will kill the CPU very quickly.

Simon