Sunday, September 18, 2011

DPS Killer - Revisited

The worst kind of DPS killer. Latency
We had to call the raid last night because of lousy DPS on even the easiest BH bosses. Here's the culprit.4 second latency.The raid went something like this:
  1. Raid  leader announces we're all ready. "Let's go!"
  2. DBM pops up for bosses special ability.
  3. I am still standing at the feast waiting for everyone to move.
  4. All the sudden, the last 4 seconds of fighting zip by in half a second. Bosses special ability is triggering. 
  5. I run to join the fight, but aren't in location. 
  6. I cast my dots, then the game pauses. Tank is running in place again. 
  7. We're dead and I am now asked to release from my dead body. 
3 attempts at the boss and I called it. It was not going to happen. After about an hour of diagnosis, I was able to fix my problem.

wiring cabinet
Here's a basic idea of what I am working with:

  1. Coming into a wiring cabinet I have my Comcast router, feeding into a D-Link router. (each room in house has a cable drop, hence the full assortment of black coax cables)
  2. The DLink has a 4 port switch which feeds my BluRay player in the master bedroom, TiVo in family room, Kids PC upstairs and my gaming PC downstairs. (Yeah there is a lot of blue wire above, that's a drop for the kitchen, kid's rooms and 2 more drops in the family room)
  3. The DLink also provides wireless connectivity to the house. This is primarily used to support my wife's and own cell phones, but I do have a printer that sometimes get turned on.
To troubleshoot my issue:
  1. Downloaded Wireshark. This freeware application does a scan of packets across your network and returns traffic on my network. The biggest bit of information that helped here was the trace. It displays a large dark colored line when you get resubmits. I was seeing a ton of them on my network. 
  2. Eliminate gear. I went around the house and turned off all of the extra equipment. Wireshark returned a ton of traffic from various hardware bits chatting with each other. I wanted to make sure I wasn't saturated just because of a chatty piece of hardware.
  3. Then I popped open the wiring cabinet and started unplugging pieces. Unfortunately, the network cables weren't labeled well. I grabbed port 1 on the switch and plugged it directly into the cable modem. Master bedroom. Checked the Internet connectivity, 16mbs! 
  4. Flipping through all 4 cables, I found that each device was getting wonderful speeds when directly plugged into the modem. 
  5. Router or Cable from modem to router? Luckily I had another patch cable (aka short 1ft network cable) and replaced the one there. Plugged everything back in, rebooted both components and tested. 
Looking back, I should have noticed that the resubmits on wireshark detailed corruption on the line. I bet, 99% of the time this is a faulty or lose cable. Reseating all the cables in the switch and modem (yeah, the modem is hanging upside down) could have likely solved this issue. 

Here's to a happier raid this Monday! 

Update 9/26/2011 - After a short stint of really great Internet access, today, I tried to get onto the Internet over the weekend and it was down again. I believe they had hardware issues over the weekend and possibly replaced something on the back-end. When I called Comcast this morning, and they informed me after a little testing, that my modem had gone bad. I picked up a new modem from the local office and will be setting it up after work today. Hopefully, this solves my problem for good.

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