ping and tracert networking question
 

Need some help from network gurus.

My internet access at home is via WISP.

When it is working properly, I can ping and tracert the tower with very little latency.

Occasionally it will stop working, and I've discovered that when that happens I can ping the tower but tracert does not work (or takes an inordinately long time).

What would be some possible explanations that would fit that set of facts?

Re: ping and tracert networking question
 

This happens on my home network as well. The situation isn't exactly the same, since I don't have a WISP. Instead, I have sort of a LAN within a LAN that I use for testing purposes(I work as a researcher for a distributed systems and security lab). For me, the problem is old wifi hardware that is probably nearing the end of its lifespan, which I am also too lazy to fix until it dies completely :D

Can you give more information on what hardware you are using? That could be the problem. Also, do you know anyone else who uses the same WISP who may be having similar issues? If that is the case, it's probably an issue on your provider's end, in which case you should contact them and see if they can isolate the issue.

Re: ping and tracert networking question
 

Ubquiti AirOS PowerStation2

Re: ping and tracert networking question
 

Hmm--unless you bought it used, I doubt that's where the problem is. When it is not working properly, are you still able to navigate to a web page(i.e. make HTTP requests) successfully?

Re: ping and tracert networking question
 

No. For purposes of this discussion, not being able to access web pages is what I mean by "not working properly".

Re: ping and tracert networking question
 

Just checking :)

How frequently does this occur? Multiple times per day? Per week? Also, I assume you've taken a look at your PowerStation during these times to make sure nothing was obviously out of place?

Re: ping and tracert networking question
 

How many hops in your traceroute when it is working?
Are you going to a DNS entry or an IP?

Re: ping and tracert networking question
 

Couple of times a week. Random.

Actually, it has a Murphy sensor. Its happens at the worst possible times. Like when I'm about to submit my tax return, or in the middle of a purchase or a bank transaction.


It's on the roof (2 stories). At night I can sort of see the signal strength LEDs with binoculars.

Re: ping and tracert networking question
 

Even a tracert to an IP 3 hops away doesn't work (or takes forever).

Re: ping and tracert networking question
 

Trying to figure out if you are pinging your local gateway which will work even without the tower but tracerouting to a website which times out over ICMP because the tower is not connected (you can traceroute over UDP as well). That is why I asked how many hops when you are working I assumed you tracerouted to a fixed place in the network before the Internet.

Re: ping and tracert networking question
 

It could be DNS resolution. Most implementations of tracert will attempt to resolve each IP along the way, and this can take a long time with a flaky DNS server.

A couple suggestions:

a) Try running tracert with the -d flag (Windows) or -n (Linux).

b) Try using an open DNS service, like OpenDNS (208.67.222.222/208.67.222.220) or Google Public DNS (8.8.8.8/8.8.4.4).

Re: ping and tracert networking question
 

I thought I answered that:

Maybe I'm not understanding what you're asking.

Re: ping and tracert networking question
 

OK, this is where I have some confusion. I thought DNS was to resolve a name into an IP address. Why is DNS required if I am already providing the IP address?

Thanks. I will try that next time it misbehaves.

Re: ping and tracert networking question
 

By default, tracert will still use DNS to try to look up a name for each hop so it can display it as part of the output. Use "-d" (Windows) or "-n" (Linux) to tell it to skip that part.

Re: ping and tracert networking question
 

I went ahead and changed my DNS as you suggested. I'll know in about a week if that fixes the problem.