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Troubleshooting one-way packet loss

Hello All,

We are having issues with one-way packet loss after introducing a GRE Tunnel. It is a satellite 1Mb connection, and we are running a video conference over this. One end of the connection is completely fine, but in one direction of the call there is high packet loss leading to dodgy sound and pixelated video. We have a queuing set up on both ends exactly the same, based on the VC IP address. The queue is double the size of the actual call rate which is established (384kbps). No drops from this queue into the default queue seem to be occurring (until we made the queue have a priority of 768, packets were still being dropped from the queue). The side with the packet loss is the more heavily utilised, but i would of though the queuing should take care of it. In between in our routers (Cisco 3745's) at either end, there is the service providers routers. What check can i have them do? Presumably, once the traffic leaves our router, the service providers traffic will simply serve the GRE traffic all the same. But as our routers should be servicing the VC traffic first, then the service providers routers will get this traffic first anyway.

Any steps you coul advise me to take to nail this.

Many Thanks


  • WAN Routing and Switching

Re: Troubleshooting one-way packet loss


1) I'd be afraid of a audio quality over any satellite line. What's the round-trip delay on your connection? (AFAIK, 150 ms  is recommended as a maximum for VoIP.)

2) I can imagine a case your line is OK but there is a congestion somewhere on the path to the destination.

Do you have any QoS agreement with your provider?

I suppose you have configured  qos pre-classify on your GRE interfaces.

So together with the IP Precedence for GRE Tunnels feature it might be possible to run some QoS inside the provider network for you?

(See or for details.)



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