frame relay ping loss

[kkalaycioglu]

On frame relay circuits especially with packets of 1300 - 5000 bytes long, success of extended ping is about %96 - %97.There's always a loss between %2 - %4. When I check the interface, I see no layer 1 or 2 errors. Bandwidth of the circuits are sufficient. What may cause that loss?

[scarothe]

Greetings:

Turn on IP Packet debug on the router at each end. Ping and see how many packets arrive at one end and then on the return trip reach the router than originated the ping. This will tell you in which direction the packets are dropping. Once that is done, you will know in which direction they are dropping. How big is the ckt? CIR?

Thanks...Steve

[kkalaycioglu]

Hello Steve,

These circuits belong to a production network and both sites are far from me, so I think I won't be able to perform the test you advised. But in a few days I'll try to simulate this case in a lab network (We're using a private FR network which is being operated by my company). When it comes to your second question, router at hub has 2 Mbps (E1) link to the FR network, remote routers has 512Kbps connection. I've configured FR traffic shaping with a CIR of 128, 256, 512 Kbps at both ends of the circuit bu it's no use. Most of the FR circuits in our network expose ping losses about one-two packet in one thousand packets. The strange thing is that neither routers nor FR switches indicate physical or layer 2 (FR) errors. Have you got operational experience with FR networks? What is the ping loss rate of operational networks?

Thanks for all. Kivanc.

[hchebli]

Hi Kivan;

you might need to find out what FR switches your company is using. I don';t think your FRTS will help you in this case as you would know that FRTS is only aplicable in congestion scenarios. Even if you remove FRTS on both sides you will get the same problem...Do you get it at all times? Is the link congested?

Also, is the backbone of your company's network ATM? if so you have to account for about 15% increase in overhead when you convert from FR-->ATM

regs..hassan

[kkalaycioglu]

Hi Hassan,

We're using Netrix switches. When I check router interfaces or corresponding FR switch interfaces I see that there's no congestion. Yes, I get it all times. Loss is about 1,2 or 3 packets in a bunch of 1000 ping packets. It's not an important value but anyway, I believe that those circuits should work smoother. We're not using ATM at the moment. And as you say FRTS hasn't helped.

Regards. Kivanc.

[cantoron]

Yes, I think it concern about the FR switch or congestion. Do you see any FECN or BECN at interface?

[kkalaycioglu]

Hi,

No FECN or BECN on router or FR switch interfaces. Also there's no frame discard at FR switch.

Thanks.

[kkalaycioglu]

Hello,

I've discovered the problem. On the frame relay switches that we use there are two possible trunk configuration as to how the frames will be transported between switches: unreliable (for use with reliable transmission facilities-default) and reliable (for unreliable transmission, a proprietary technology reminiscent X.25). I've reconfigured the switches to use reliable system. It added a piece of delay but it's no important. Thanks for all.