I had one hell of a networking problem crop up at a client the other day. I was called in to troubleshoot an odd problem where some machines suddenly could not get to the internet... sometimes.

Damn I just LOVE problems that start like this. I poked around and checked their router and rebooted their shittier-than-turds Dell VLAN switches and came up with nothing.

The router has several interfaces and the only ones being affected where those which have VLAN's on them, so I was fairly suspicious of those Dell switches since they've given me trouble with VLAN's before, but the symptoms here were downright bizarre.

I did some packet monitoring and some other experimentation and came up with the following observations:

- Local internetwork traffic is mostly passed just fine (there was one case where we saw some packet loss from one VLAN subnet to another but it could have been a fluke)
- From the affected machines, Internet bound traffic goes in the switch and never comes out-- doesn't even make it to the router.
- Moving devices from one switch port to another would sometimes make them work--or if they were working, fail to work. But the problem was never static across any given ports.

After several hours of troubleshooting and headscratching, I had but one pathetically weak theory. I knew that new device had been connected to the network, and we eventually found that after unplugging this device, the problem seemed to gradually clear up, however plugging the device in did not reintroduce the problem, at least not within a reasonable period of time. The new device was connected across a hallway using a patch cable that was getting walked on. The cable under the hallway rug was stupid yes, but I didn't immediately associate it with this strange network-wide problem, but that became my main hypothesis, because everything else had been eliminated.

So we tested it. We went and started jumping up and down on the cable and sure enough, some of the machines on the network lost Internet connectivity. And unplugging the cable and rebooting the switches restored it.

So there you have it. Bad patch cables can seriously fuck up your network, especially if you're using Dell switches. But wait, how does one broken cable connected from a switch to just one device cause only certain packets with certain destinations to disappear? I HAVE NO FUCKING CLUE!

Posted by ra in computerish at 22:52 | Comment (1) | Trackbacks (0)

I've come to rely on my phone for much more than just calls. It is my morning alarm clock. I take pictures with it all the time. It is my wristwatch and calendar. It is my modem when I have no ethernet/wifi.

So that I am still carrying an original RAZR makes me feel just a bit crippled. I do get along OK with it, but the VGA camera is killing me, the lack of even EDGE for data use sucks, and bluetooth on this thing drives me fucking nuts (want to use bluetooth headset? might as well reboot first since 4/5 times it won't work otherwise. Want to send 20 pics via bluetooth? You have to select the recipient device before sending each one --UGH). So I'm thinking it's time for a new phone.

I had been kicking around the idea of a smartphone for a while but I've been really unexcited by everything out there. I've defiantly kept my PDA (Palm TX) and phone separate all this time but I think I'm prepared to relent, if I can only find the right device. The truth is my Palm is dying. Maybe it has cancer of the touchscreen, I don't know; but what's clear is that it is getting less reliable and less usable all the time. On the bottom half of the screen, my pen touches register about 1 mm above or below where they really are. This throws off my graffiti at times, and makes using the onscreen keyboard nigh-impossible. Then there are the crashes. I didn't used to experience them much, but now they happen all the time. Blazer is the biggest culprit but earlier I simply ticked an option in the system prefs and it abruptly reset on me.

My mind made up, now I just need to find this mythical device that will combine and improve upon the capabilities of my RAZR and TX.

Uh oh. It doesn't seem to exist. I wouldn't consider windows mobile anything unless I were to first get a lobotomy, so that's out. I want to like the Treos, but this is 2008 and I can't bring myself to buy a NEW phone running Palm OS 5. The iPhone is cool, but is more or less incompatible with my Linux desktop/PIM. Anything else I've found (which isn't much) just doesn't move me. At this point I think there is only one hope.

Android. I am watching and waiting, with great anticipation, for the first Android-powered phones. I don't know if they will fulfill my every desire, but they certainly have the most potential, and I really hope they live up to the hype because they are pretty much my last hope.

Posted by ra in gadgets and phones at 21:44 | Comments (0) | Trackbacks (0)

Kind of like VOIP, but the voice is mostly replaced by silence.

I put together my awesome Asterisk server last year, bought five SIP phones on ebay, and was ready to rock. I guess I was thinking "if you build it, they will call" but it's been a bit lamer than that.

It's not all bad though. Despite that hardly anyone dials our VOIP number because they already have our cell numbers, it's nice to have for emergencies if teh cell network is doing the suckage, or battery is dead, etc. Most of our calls are internal (call downstairs from the bedroom, etc), which is certainly convenient, even if it seems a bit silly at times.

I have been racking up some minutes on my home-office VOIP line however, which rings only at my desk and the softphone on my laptop, so I don't feel that my PBX is not going to waste, even if it is underutilized.

I still need to finish hacking my PAP2 ATA (ugh., still haven't broken in) and I'm going to play with conference calling when I get a chance, and oops-- I still need to arrange to test 911 dialing; but in the mean time my little Asterisk server is doing everything I need and much, much more.

Posted by ra in computerish at 01:24 | Comments (0) | Trackbacks (0)

OK, I'm back and I'm going to try not to let my blog rot, like almost EVERYONE else's I know...

Recently I've had a awful pain in my side, and it turned out to be a pointy Cisco license restriction.

It started with sporadic trouble at the client as they began to use their VPN's more heavily. They had purchased a Cisco ASA 5505 to use as their VPN router, on my recommendation, and everything had been fine until we added another IPSEC tunnel and had more people accessing the remote sites. After some experimentation, we found the magic number to be 10 users, after which no one else could connect to anything across the VPN's.

Whoa... that sounds just like the "user" limit on this device! I hate user limits. Artificial restrictions on the capability of some hardware tends to piss me off. But I digress... This user limit restriction was a complete surprise because although we purchased a "10 user" ASA, I had talked to two different Cisco reps before the purchase to clarify the meaning of this and had been assured that this "user" limit did not pertain to users/IP's connecting over the IPSEC tunnels, and we didn't care about anything else as this device is strictly a VPN-gateway--they already have a m0n0wall in use as their primary internet gateway router.

So, Cisco screwed up. Fortunately I am a digital pack-rat and could produce a year-old email proving that the rep told me that the "user" limit meant 10 IPSEC tunnels with no limit on number of users. The truth is that there were two limits: 10 tunnels AND 10 users/IP's. Unfortunately, it took about two and a half weeks of dealing with assorted Cisco people to finally get a resolution, in the form of a free unlimited user license upgrade.

The outcome is satisfactory, but it really pisses me off that I had to waste so much time troubleshooting and getting it resolved after I tried hard to avoid this very problem by contacting them before buying. Furthermore, based on my conversations with half a dozen Cisco employees I can say that most of them didn't really understand the licensing terms of their own product, which is pretty sad. How am I supposed to understand if they don't? The less clear the license terms, the more likely that someone is going to get surprised by some restriction at the worst possible moment, and then swear off ever buying that brand again.

Posted by ra in computerish at 00:35 | Comments (3) | Trackbacks (0)

I mentioned in a previous post that I had, for a time, both DSL and cable internet; but I didn't go into detail about how had my router hooked up to both lines, routing traffic over them concurrently. It's time to rectify that omission. Although this multihomed configuration did not last long, I'm still using pretty much the same tools/config to take advantage of the multiple IP addresses I've managed to snag from my ISP.

This is how I've setup my Linux 2.6-based router using 'ip route', 'ip rule' and iptables to get WAN-bound traffic coming from the local subnets to exit one of several WAN links depending on different criteria; mostly source IP.

Posted by ra in computerish at 22:49 | Comments (0) | Trackbacks (0)

I've become a really big fan of Penny Arcade this year. I read it like... three times a week. Sometimes I look through the archives to see what I missed back when I didn't know of PA's existence. These are a couple of my absolute favorites.

http://www.penny-arcade.com/comic/2005/07/29

http://www.penny-arcade.com/comic/2005/09/26

http://www.penny-arcade.com/comic/2006/04/05

Posted by ra in other geeky stuff at 22:22 | Comments (0) | Trackbacks (0)

My router had been begging for a VLAN switch for some time. With seven ethernet interfaces, things were getting a little out of hand.

While designing a wireless network for a big client and spec'ing out the hardware, I found just the thing. The Netgear FS726TP. Like many people, I've been burned by the crappy plastic-encased Netgear consumer grade stuff in the past, however I'm a big fan of their higher quality ProSafe gear, especially the WG302 and WG102 access points which comprise my home wireless network.

I was impressed with the specs of the FS726TP, for the price, and had tentatively planned to buy one for myself once the client's project was complete and I had verified the switch would meet my own needs as well. As soon as the gear for the project came in, I put the switches to the test.

Posted by ra in computerish at 09:29 | Comments (0) | Trackbacks (0)