lost packets

Unanswered Question
Sep 26th, 2007

I have a leased line 64kbps. Today it started loosing packets more than 50%. Also the time for sending the packets was too much. According to the telco company that's my problem.(i am not sure if the telco is telling the truth)

What might be the problem? Is there any commands which i can do so i could figure out the problem and correct it.

Also on my router there are 7 more connections (all leased lines) and they are working ok. Only this has this problem.

What shall i do.



PS.The router is 7200VXR connected to 1800 series cisco router. The ips on both sides are ok since it was working until today for the last month. Layer 2 protocol HDLC. No access lists no encryption. Routing protocol RIP v2. Also running EIGRP distance 170.

I have this problem too.
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Danilo Dy Wed, 09/26/2007 - 06:13


Check the modem. If 109/DCD is ON and Quality is "A" this means the Telco line is OK. If not, show that to your Telco Service Provider.

Try replacing the Serial Cable between the router and modem, both sites one at a time.



moses12315 Wed, 09/26/2007 - 06:23

i will replace the cables tomorrow(my company is closed now). I will inform you about the rest also tomorrow.

Thanks a lot


pciaccio Wed, 09/26/2007 - 06:13

In order to home in on the issue at hand we need to know more about the problem. Can you please post the results of the SHOW INTERFACE and SHOW CONTROLLER commands. These will tell us what type of errors and drops you are getting. Slso if you can post the configuration of the router will also help....Thanks..

Danilo Dy Wed, 09/26/2007 - 22:57


I see the TX/RX for both is over 200. I also see huge drop of packets. Other info in the output doesn't help much. Did you check the external modem at both sites? What is the value in "Quality"? BTW, your modem may not have that information/feature.

Do you have historical record of bandwidth consumption? i.e. MRTG graph, to see if there was a dramatic change of bandwidth utilization when you start experiencing packet drops?

If the value of the modem "Quality" is "A" and there was no dramatic change in your bandwidth utilization. Will you be able to perform loopback test? Check with your Telco Service Provider to help you set the modem to local loop mode and perform extended ping http://www.cisco.com/univercd/cc/td/doc/cisintwk/itg_v1/tr1915.htm#wp1021262 this is to isolate whether the problem is in the main site or remote site.



Kevin Dorrell Wed, 09/26/2007 - 23:58

I see the rx and tx load are close to 100%, and you are dropping lots of packets from the output queues. I also see lots and lots of conversations.

I really think the problem is simply that the line is way way over utilized. Now that could either be because you are trying to fit a quart into a pint pot, or because there is some rogue traffic that is saturating the line.

Without knowing a little more about your traffic, I cannot really say which. If you are expecting this level of heavy traffic, you will just have to invest in a faster line. If not, you will have to start using QoS tools to try and analyse what this traffic is.

Kevin Dorrell


paul.matthews Thu, 09/27/2007 - 02:30

Anther vote for an overloaded link - I am with Kevin and Dandy.

I think you need to get a look at the traffic on that link - it may just be traffic has increased and caused a problem, and you need more bandwidth, someone may be being a little naughty and doing PtP type applications, someone may have a virus. In a modern network a single PC can easily fully use a 64K link.

moses12315 Thu, 09/27/2007 - 07:46

The value on both sides of the modem is quality A i checked that.

i do not think is the traffic. The users on the remote side are only 3 and during evening i had the multiping program running . The situation did not changed(i attach a sample of the multiping program. The PRTG program did not work even i changed the packet sizes to its min. I also closed the connection today for 4 hours but nothing changed. i also changed all the cables on both sides and also the serial port of the root side. The only thing i did not do is changing the router at the remote side.(cisco series 800)

Historical the telco company is unreliable. The same thing happened to an onother side and they said it was not there mistake. Finally they fixed it. The list line was 2Mbps that time.They said that the line even thought it was looking ok it was full of erros and the stack of the modem was full. So they fixed the line and reset the modems.

Anyway i want to thanks everyone who is helping people like me. This is a very good side and extremelly helpfull for people without experience like me. Thanks again all.


PC. I will call again the Telco company tomorrow to fix it.



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