One for the 4E65726473 among us

[Chems]

This is a bit of "have you ever experienced this" for the hardcore computer guys here.

Just like I'm sure the rest of you do, I look after a few of my familys computer setups. The one at my family home started acting up last week. Its not an overly complex system. It consists of a set of 3 distributed network points connected by PoE plugs. Ones the router and main computer. Another is the media server and network printer and another is a media player, on top of this about 10 wireless devices use the network. The problem was that communication between any of the devices on the system slowed down to nothing, causing lag of around 10mins for a print job to arrive. Any browsing of the media server would also cause a freeze for that explorer window. The knock on of this was that if you tried to open or print on any computer that used the system that would freeze up for ages until it connected as any file window opened would display and engage the networked drive.

So I started methodically tracking it down this evening. I ruled out any local computer problem first as it was happening on all. I ruled out the media server. Then the router. All that was left was the PoE plugs. I finally decided they were ok.

After a good 45min to one hour of unhooking all this kit I discovered the problem. One of the cat5 ports on the router seems to have died. By switching the cable to another port it works just fine. I don't think I've ever experienced this before, but for sure it'll be the first thing I try in the future. My question was what do you think causes just one port to fail. I'm like 99.9% sure its not a software error. The router is about 3 years old and is always on. Just worn out? Partially working but not fully seems an odd way to fail.

 

[PMK54]

The failure of a single port is probably quite common because if they are like mine, each port has an interface circuit next to the socket and such devices are likely to fail at some point. How is the cable that is plugged into that circuit routed physically? Is it likely that a switching spike in an adjacent cable or electrical device could have induced a damaging voltage in the cable? Did you experience an electric storm in the recent run of bad weather? The failure wouldn't necessarily occur straight away, a protection device on the port might fail open circuit, then the first switching spike say in a tumble drier or immersion heater might kill the more sensitive circuit elements.

 

[Racers]

Hi,

The ports are protected by isolation transformers and shouldn't suffer from spikes, I can't remember the last faulty port on a network swtich at work and we have up to 100 meters of cable on each port.

Did you try a reboot in case the port has locked up?

Pete

 

[cambournepete]

Hi,

The ports are protected by isolation transformers and shouldn't suffer from spikes, I can't remember the last faulty port on a network swtich at work and we have up to 100 meters of cable on each port.

I can't recall one either.

I did have a couples of odd problems myself recently:
Internet browsing was really slow and the iDevices couldn't download apps. I rebooted both router and cable modem to no effect then turned them both off for a while and back on and hey presto! - everything OK again.

My netbook wouldn't talk to our printer anymore. I'd recently upgraded it to windows 7 and installed the printer drivers but it couldn't even see the printer. Ping didn't work either. Even more peculiar was that the printer wasn't list in their address table on the router. I'd set the printer up with a fixed ip address so that all our computers could easily find it. more in desperation than anything I set the printer to DHCP but reserved the same ip address for it in the address table in the router. Rebooted the printer and then everything suddenly started working again. Why?

Sometimes I really hate IT!

 

[AndyT]

Zinc whiskers?

 

[Eric The Viking]

Zinc whiskers?

Ah yes - another gem from our dear friends in Brussels. Worth noting that lead free solder also requires higher temperatures to melt, tins less efficiently and suffers from vibration cracking. I've found far more dry joints in consumer products than before the directive came into force, and that's only in one, domestic environment (our house, avec three young people and their toys).

Sigh.

E.

PS: on-topic: I did once have a port fail on its own, but that was years ago. I couldn't diagnose it beyond that, and put it down to component or soldering failure. Really throws you, though.

PPS: @ Roger: were you using Power-over-Ethernet (for the hubs/routers), or Ethernet over mains? Our local 11kV substation blew up in an 'interesting' fashion a few weeks ago. I'm glad I wasn't using any of those Ethernet-over-mains jobbies when it did.

 

[RogerS]

Yup...FTP'ing a file up to my website. Perfectly happy if I tried to FTP a test file of a few bytes.

But try to FTP a file of anything much larger and it all just failed.

That kept me going for a whole day trying to find the problem. Turned out to be the router. Why it was OK with a file of 1KB but not one that was 10KB I will never know.

Such a cathartic moment, wielding that sledgehammer.

 

[cambournepete]

Why it was OK with a file of 1KB but not one that was 10KB I will never know..

possibly because the 1kb file fits in one data packet but 10kb doesn't and somewhere the linking between them didn't work. 'tis odd though

 

[whiskywill]

I have just read all of these messages and now my head hurts.

....Maybe an hour on my Commodore 64 will ease the tension.

 

[Eric The Viking]

possibly because the 1kb file fits in one data packet

I thought they had a 256 byte payload?

'Tis almost 20 years since I last looked at that stuff, and it was really basic (i.e. 50 Ohm co-ax) Ethernet.
I assume all the stuff with go-faster stripes is different.

Never mind the Commodore 64, I'm off for a game of Pong down the pub to de-stress...

(homer)

 

[JakeS]

possibly because the 1kb file fits in one data packet

I thought they had a 256 byte payload?

On one hand, IIRC it's negotiable; when the connection is first established one of the things the two endpoints do is establish how big a packet they can each deal with.

On the other hand, your OS will probably tell you that any file greater than 0-length and less than 1kb is 1kb in size anyway - Windows certainly does. It could well have been the case that the so-called 1kb file was actually a 100-byte text file.

(And to confuse matters further, that 100b/1kb text file quite probably occupied 4kb of the hard disk thanks to the filesystem... ;-))

 

[Chems]

@Jake, all depends on what the programmers set the pragma packing too. . . So if it was Microsoft that 1kb file probably uses 16kb of space!

Thanks for all the replies. It great to hear what others make of it, and to see someone else suffered something similar. Those whiskers would explain a few recent deaths of long running network appliances. I always just thought it was the constant heat of an always on item that finally did the joints in in someway.

 

[devonwoody]

Interesting point there regarding soldered joints. Does that mean that many white goods are going to get more failures because of this?