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

[Pete Lumbis]

The use of tunnel keys can also cause punted packets on 6k


On Mon, Mar 25, 2013 at 8:36 AM, Samir Abidali
<samir.abidali at gorannet.net>wrote:

> 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
>
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