Ugh! Sorry, gang - I just accidentally deleted a message about packet loss at the source. Here are some of the posts that I had cached (but I only have a few of these).
-------------
First message about packet loss, trying to figure out why only the final destination shows, and all intermediate hops show as 100% packet loss (message lost):
-------------------- Response 1 ----------------
Hi.
I'm going to assume that you're using the same DSL hardware you were previously (I've seen this happen because of hardware problems, but if you're using the same hardware, then that's for sure not your problem).
The Ping Plotter tutorial has an introduction to how trace route works - so I'm not going to run through that any more than what is specifically related to this problem.
So, Ping Plotter sends out packets with a TTL=1 to TTL=(your route length) and each router along the way responds. If any router sees that TTL=0 then it responds back with a "Expired" response, to say that TTL=0 when it got to it and it can't go any further. This is to stop a packet from being routed in a loop between several routers forever - which you can imagine happening if there was no concept of TTL. So, all the routers between you and the final destination are going to respond with a ICMP expired packet. Ping Plotter uses these to know about these routers - since each router sends back its IP address with this packet - and Ping Plotter also times how long this packet takes to return. Now, the final destination is a bit different - as the final destination is going to respond back with a different kind of ICMP packet - one that says the final destination was reached successfully.
I'm guessing that your ISP is not passing returned ICMP expired packets, but is passing packets that say the destination was successfully reached. This is likely a router/firewall configuration issue within your ISP.
Based on the behavior you're saying, I would with almost certainty that packets are leaving your ISP correctly, but just not returning. Now, you can make some guesses about where the problem on the return path exists by seeing if any routers are responding. If you're seeing something at hop 1, but not hop 2, then your problem is likely hop 1 or later. If, however, you're seeing hop 3, but not hop 4, then it's hop 3 or later. This is important in that you know if it's a border firewall (coming into your ISP), or something closer to you (like a gateway). It sounds like you're not seeing anything even at hop 1 - which leads me to beleive it's an issue with the router at, or very near, your gateway (hop 1).
I would suggest starting out with your ISP talking about getting the Windows "TRACERT" working from their end. If it's working for them, but not for you, then it's something *very* close to you - between you and them. If it's not working for them either, then they should be able to troubleshoot the problem from their end.
Hope that helps at all. Feel free to re-direct any questions you may have. Please let us know how things turn out as well!
Pete
---------------------
Several followup posts saying they see similar, the most recent on 11-14-2002:
I'm having the same issue. I assumed it was a problem with my Linksys router not doing ICMP echo. I went into "filters" and disabled "Block WAN Requests" with no luck.
The access from my cable company has got to pot lately and I'm getting 25-50% packet loss. I sure wish I could get this to work to learn more about the problem.
Previous Topic
Index