3725 ISDN Problem

mike.f · ‎01-30-2003

I have a random problem with my internet freezing up. It is accessed via a 128k multilink ppp link. The background, the 3725 has a 4 port bri module, one port links directly to a remote office, one is the link to the internet, two are unused, there are aprox 4 to 5 users max at one time plus email dialing out every half hour, the remote link works fine. The symptoms, you will be surfing the web downloading a page it will get really slow to the point of almost freezing, if i ping an external address it will reply but dropping packets. If the web page is just left there half loaded and nothing else tried the line eventually drops, if you then try to surf again the line comes up and all is fine.

So far i have tried posting my config on this forum and it was ok'd, i have contacted my ISP they say it is ok their end and they have a recommended a cisco config to try, i have used that and still have the same result. I have tried taking off multilink ppp and running on one 64k channel, this was alot more reliable but the problem did still occur, i've run out of ideas. The internet is accessed via PAT with one ip address and a static translation on port 25 for the email server. The router is not heavily used, i may be wrong but i've a feeling it's external to the router. Any ideas or how can i prove anything?

vsarin78 · ‎01-30-2003

Try finding out where exactly the packets are dropped. try pinging from different interfaces of router and use traceroute to an external IP. Also make sure that there is no conflict of ur static IP with any other IP of service provider at the time when problem occurs.

All the best

mike.f · ‎02-03-2003

I've tried swopping the physical ISDN line with our remote branch to eliminate the ISDN the problem is the same. I tried a traceroute to the ISP's DNS server, it goes through two external hops to get there and packets are dropped randomley. At each hop, so it could be the first device causing the prob. However i don't know what is the norm, if a large email is coming in for example and a couple of people are surfing ,surely some packets would get dropped and how does the interface sort priority is it first come gets most priority or the email with the fixed port, is there a way of customising priority?