Minor Mystery at EmCit

[kevin_standlee]

As I came back from my walk at lunch (about which more later), I got a phone call from cherylmorgan, who in a worried tone of voice told me that Emerald City was off-line. I checked from my work machine (via the company firewall, Internet Explorer) and hit reload, and it came up just fine. I tried on my personal machine, on a friendly nearby open wireless connection, (no firewall, Firefox), and it also came up fine.

I called Cheryl back on Skype (better than the mobile phone) and reassured her that EmCit is not off the air, although it may be for her. We tried a few tests. I can see the specific server at her hosting service on which EmCit lives, and hit it; she can hit the other servers at Pair, but not the one on which EmCit sits.

Cheryl fired up an older computer that she doesn't use very often, and it also could not see the site, although both machines can still see Cheryl's personal site and other web sites hosted on Pair. This seems to narrow the problem down to somewhere between the router in Somerset and a specific Pair server. Cheryl rang off and tried some troubleshooting at her end on the router. No luck.

She'll have to wait until tomorrow when she can contact her UK ISP during normal business hours, it being after 11 PM there. She'll also contact Pair, to make sure they haven't blocked her from their end for some reason.

While we work on the issue, I posted a message on the EmCit blog to let the regular readers know that there is an interruption of service for an unknown period.

Comments

[bovil.livejournal.com]

I had a similar pmroblem while at FC; I could see some servers at pair, but not mine (and not some other servers elsewhere).

Have Cheryl try a traceroute to one of the pair servers that she can see, and follow that up with a traceroute to EmCit.

The second traceroute should follow the same path as the first, but break at some point. The last identified hop may be where the problem is, or perhaps the first one that you can't see. Once you've identified the break point, send the traceroutes to support@ whatever provider is listed as the name of the machine.

[kevin-standlee.livejournal.com]

I shall pass this on to her. She's already gone to bed, however, after sending a query off to Pair, and she's off to London in the morning.

[bovil.livejournal.com]

Pair will tell her the same thing.

[kevin-standlee.livejournal.com]

That is indeed what they did do. It looks like the the tracert command is always "trace from me to there," so she'll have to wait until she gets back to Darkest Somerset to diagnose the problem. While she's in London, she's been able to get online and see her site via other people's computers.

[bovil.livejournal.com]

So the geeky level...

tracert (or traceroute, depending on the system you're using) is a variant on ping. Rather than just echoing whether the destination host is reached, the ICMP (Internet Control Message Protocol) packet instructs each device it passes through to echo back its name and the status of the request.

And yeah, it's dependent on the source of the trace. If Cheryl tried to do a trace from London, it would give her the working path from London. This isn't necessarily a bad thing to capture. It's a good base for comparison.

The important thing is the trace from her connection in Somerset, which will show where the route breaks. It's also worth doing a trace to a server at Pair that's reachable from Somerset; comparing the three routes (London, working-at-home and not-working-at-home) will give a pretty clear indication which router is fried.