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Beginner

Limiting bandwidth in GRE Tunnel

We have two Cisco 2811 Routers setup with a GRE tunnel that we would like to constrain the bandwidth on to replicate a

satellite connectinon of 400 kbits. We tried the bandwidth command 400, but from what I understand that is only for routing metrics and not actual speed of the interface. Any suggestions?

Thanks!

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Hall of Fame Guru

Limiting bandwidth in GRE Tunnel

Scott

You are correct that setting the bandwidth in the tunnel interface is for routing metrics (and perhaps network monitoring utilization reports) and does not change the physical performance of the tunnel. You might consider configuring traffic shaping on the physical interface where the tunnel is terminated. With shaping you can constrain the traffic to a specified capacity.

HTH

Rick

HTH

Rick
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Beginner

Limiting bandwidth in GRE Tunnel

Rick,

We are also running EIGRP over the tunnel, would this cause any issues?

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Hall of Fame Guru

Limiting bandwidth in GRE Tunnel

Scott

It depends. If the tunnel is configured with a high bandwidth and you use shaping to constrain the traffic to a low rate it is possible that EIGRP could be impacted (though I think it is not very likely). The issue is that by default EIGRP will try to use up to 50% of the configured bandwidth for its updates. If there is a big mismatch then EIGRP might be impacted.

The safe thing to do is to configure a bandwidth on the tunnel that represents the capacity that is actually going to be available.

HTH

Rick

HTH

Rick
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Beginner

Limiting bandwidth in GRE Tunnel

Why not do an MQC shaping policy outbound from both tunnel endpoints to shape the traffic on the tunnel interface.Here is an example

http://www.cisco.com/en/US/tech/tk543/tk545/technologies_tech_note09186a008017405e.shtml

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VIP Expert

Re: Limiting bandwidth in GRE Tunnel

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Posting

As the other posters have noted, a shaper might be used to replicate your satellite bandwidth.  However, one aspect of satellite behavior that would be difficult to replicate on 2811 router, would be the high latency.  If you need to replicate that too, you'll likely need an external "appliance" to delay your traffic.  (Such appliances can might also emulate lower bandwidth and/or packet loss too.)