Traceroute

[LadyShea]

Okay, here's the scenario

Out of 100 people throughout the country, about a dozen can't access a specific website, the rest can.

Assuming this is due to a router outage, let's say now I have everyone run a traceroute. Will the traceroute STOP at the bad router, or what will it return results wise?

[viscousmemories]

Yes, the traceroute should stop at the bad router.

[JoeP]

Yes ... however, the traceroute could also stop at any router that's set up not to respond to "icmp" requests (and that's quite common now), so it may not be conclusive.

[LadyShea]

It's amazing how many people don't understand the Internet. If they can't access website A, it's due to website A being down...even though everyone else can get there. One guy told me "It's the only website I can't access"...um, no, it's the only website you are aware of you can't get to.

[JoeP]

So, is it fixed yet? I can't stand the suspense!

[Corona688]

Yes ... however, the traceroute could also stop at any router that's set up not to respond to "icmp" requests (and that's quite common now), so it may not be conclusive. I'm not sure it actually stops there if a router doesn't answer icmp. tracert doesn't control the route, after all, just how far down the rabbit hole the packet goes. I've seen routes with "holes" in them.

[LadyShea]

So, is it fixed yet? I can't stand the suspense!

Oh yeah, within a day. I know for a fact it wasn't us now as we can't fix anything in such a short time period...well and the fact that I could access from bumfuct nowhere Deep South

[curses]

Sooo, I have a question about traceroute.

Let's say that I run the command on a site with the output:
C:\Documents and Settings\user>tracert UK Urban Exploration Forums (www.28dayslater.co.uk)

Tracing route to 28dayslater.co.uk [83.98.156.237]
over a maximum of 30 hops:

1 <1 ms <1 ms 1 ms 10.0.1.1
2 * * * Request timed out.
3 * * * Request timed out.
4 9 ms 9 ms 9 ms ge-2-2-ur01.n1alpharetta.ga.atlanta.comcast.net
[68.85.233.77]
5 10 ms 8 ms 9 ms te-9-1-ur01.n2alpharetta.ga.atlanta.comcast.net
[68.86.106.222]
6 10 ms 9 ms 9 ms te-9-3-ur01.g1norcross.ga.atlanta.comcast.net [6
8.86.106.226]
7 9 ms 9 ms 9 ms te-9-1-ur01.d9chamblee.ga.atlanta.comcast.net [6
8.86.106.142]
8 10 ms 9 ms 9 ms te-9-1-ur01.d8decatur.ga.atlanta.comcast.net [68
.86.106.146]
9 9 ms 9 ms 9 ms te-9-1-ur02.d1stonemtn.ga.atlanta.comcast.net [6
8.86.106.150]
10 10 ms 9 ms 11 ms te-9-1-ur01.d1stonemtn.ga.atlanta.comcast.net [6
8.86.106.154]
11 10 ms 9 ms 8 ms te-9-2-ar01.d1stonemtn.ga.atlanta.comcast.net [6
8.86.106.158]
12 13 ms 11 ms 11 ms te [68.86.106.1]
13 12 ms 20 ms 20 ms 68.86.90.121
14 30 ms 28 ms 28 ms te-0-0-0-0-cr01.mclean.va.ibone.comcast.net [68.
86.84.70]
15 30 ms 27 ms 28 ms TenGigabitEthernet8-3.ar3.DCA3.gblx.net [64.213.
54.149]
16 * * * Request timed out.
17 * * * Request timed out.
18 * * * Request timed out.
19 * * * Request timed out.
20 * * * Request timed out.
21 * * * Request timed out.
22 * * * Request timed out.
23 * * * Request timed out.
24 * * * Request timed out.
25 * * * Request timed out.
26 * * * Request timed out.
27 * * * Request timed out.
28 * * * Request timed out.
29 * * * Request timed out.
30 * * * Request timed out.

Trace complete.

Now I know this site is up and running, and I was able to access it last week. I see that it starts timing out at TenGigabitEthernet8-3.ar3.DCA3.gblx.net . Now I run traceroute on another site that I know to be up and running but inaccessible by me this week, and I get roughly the same results. I'll spare you the results but it's the same minus the ping times. The only thing that's changed on my end is my wifi card. Is it possible that the issue is the new card?

[Ensign Steve]

It doesn't look like the problem's on your end, as you are able to get out of georgia and comcast and into the "ibone" in virginia, probably the launching point for the transatlantic hop. I think all the ping timeouts mean those servers aren't set to send icmp replies. Are you still able to get to the website? I get the timeouts as well on my traceroute, but I still can get to the web page.

So do you find comcast service in your area to be blazing fast? I get about 6 Mbps. It's one of the things I'll miss most when I move.

[curses]

I've got two sites, madwifi.org and 28dayslater.co.uk which both stop there. Can't get to the sites at all this week, but know that both of them are up and running.

The comcast is nice, I'm about 4.5Mbps.

[Ensign Steve]

Weird! I guess the problem is on your end after all, because I can get on both. Want me to read them to you? :P

I don't think your answer lies in traceroutes, though, as mine look exactly like yours, but I can still view the webpages. Sorry, I realize that's not a ton of help. :(

[curses]

Weird! I guess the problem is on your end after all, because I can get on both. Want me to read them to you? :P It's coming to that, I really need to get to the docs section of madwifi so I can install the wireless driver right.

I don't think your answer lies in traceroutes, though, as mine look exactly like yours, but I can still view the webpages. Sorry, I realize that's not a ton of help. :( It's cool, I can imagine that the problem lies either with the access point or the modem as none of the computers on the network can get to these sites (checked this morning)

[Ensign Steve]

My buddy at work thinks it's a DSN issue, which would account for the other machines on the network having the same problem, but your traceroute is resolving the 28dayslater domain to the same IP address that mine is.

I'm stumped! :(

Did you jiggle the cord?

[LadyShea]

Did you jiggle the cord?

Anytime I call my ISP about an outage, their only solution is to turn it off then back on. They make it sound more fancy "power down reset" or some shit...but it's more or less jiggling the cord.

[curses]

My buddy at work thinks it's a DSN issue, which would account for the other machines on the network having the same problem, but your traceroute is resolving the 28dayslater domain to the same IP address that mine is.

I'm stumped! :(

Did you jiggle the cord?I jiggled the cord AND rebooted everything ;)

I bet it is a DNS issue, we had been using someone other than Comcast, but when I started having wifi troubles, we reset the access point and didn't put the DNS servers back in! Now if only I could remember the name of the website that gave us those numbers...

[curses]

Crap. Changed my DNS servers and still no go.

[Corona688]

I'd have to say it's a routing issue somewhere down the internet. It's extremely hard for your computer to selectively bork up communication with one site unless it's intentional -- firewalls, content filters, etc. But it's perfectly possible for a router somewhere to route a few people the wrong way through slight misconfiguration, or block your IP address range from similarity to a spammer's, etc, etc, etc.

[curses]

Is this something that I'm going to need to take up with my ISP? I've actually never had this happen (as far as I know) before.

[seebs]

Curses, run traceroutes to sites you can reach.

One obvious question would be whether they're all within fifteen hops. :)

It is possible for a new network device to change a network setting such as MTU in a way which causes some routers to choke.

[curses]

well, FF's home page is 21 hops, google is 18, and yahoo.com is 23. Found the MTU setting on the router, it's set at automatic. Would there also be an MTU setting on the repeater (we're using an Apple Airport Express as a signal booster)

[JoeP]

:tmshockd:
Not one of the ping times in your traceroute is over 30ms.
:faint:

[Ensign Steve]

That's cuz they're all in the US, silly. The next hop is the transatlantic hop. My trace returned one more hop than curses' (Amsterdam) before it went to all stars, and it was in the 130's of milliseconds.