[c-nsp] GRE tunnel bandwidth

[Lee]

On 8/4/12, Chuck Church <chuckchurch at gmail.com> wrote:
> Tunnel bandwidth command (or any interface bandwidth) is used for
> statistics-computation only.  It does factor into QOS too if you use
> percentage type commands.

It's also used for eigrp route metrics.

I suspect routing isn't the issue here tho
> > I have some users experiencing slow file transfers over a GRE tunnel. The
> > tunnel is riding over 10-gig links.

To be able to use all the bandwidth, the tcp window size needs to be
at least <bandwidth in bytes/sec> * <round trip time in seconds>
So, for example, on a 10Gb link with a 2ms round trip time the tcp
window needs to be 2.5MB.  I remember WinXP defaulting to 16KB...

Regards,
Lee


>  I'm guessing there are two possible things to
> look at.  The CPU of the devices doing the tunnel endpoints is high because
> of the encapsulation, or else the tunnel MTU is affecting the clients (if
> TCP).
>
> Chuck
>
> -----Original Message-----
> From: cisco-nsp-bounces at puck.nether.net
> [mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of John Neiberger
> Sent: Saturday, August 04, 2012 11:57 AM
> To: cisco-nsp at puck.nether.net
> Subject: [c-nsp] GRE tunnel bandwidth
>
> I have some users experiencing slow file transfers over a GRE tunnel. The
> tunnel is riding over 10-gig links. I see that the default tunnel bandwidth
> is 8 Mbps. Does that mean that the tunnel is rate limited to that value? If
> so, is the simple solution raising the bandwidth with the "tunnel bandwidth
> transmit" command?
>
> Thanks,
> John
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