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Old 05-30-2009, 02:10 PM   #1
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Unhappy Bad Vent Transmit Lag / Ping Spikes

I have a MacBook Pro, 2.5GHz Core2Duo, 4GB RAM. I play WoW and use Vent. Everything worked fine up until two days ago, when people in my guild started noticing that my responses were delayed (anywhere from 15 seconds to 5 minutes) and came out choppy. I can hear others clearly and without delay. Vent reports pings of 62ms most of the time, but sometimes it spikes as high as 38000. My transmit is delayed even when the ping looks normal.

I've tried power-cycling my modem, router, computer, etc. When I first log back into Vent after doing so, people hear me clearly and 'on time', but within a minute or two I start sounding choppy and my responses progressively more delayed. I also tested WoWs crappy voice chat client with a guildmate, and it worked fine for the hour we used it.

I'm on a wireless LAN, Netgear WGR614v6 router (crap, but it's not mine so...), and AT&T (Yahoo!/SBCGlobal) ADSL using a Speedstream 5100 modem (also crap).

I know you are going to ask, so traceroute to my vent server follows :-)

traceroute to (, 64 hops max, 40 byte packets
1 ( 1.621 ms 1.419 ms 0.902 ms
2 ( 11.264 ms 10.908 ms 14.017 ms
3 ( 25.568 ms 11.838 ms 13.268 ms
4 ( 11.723 ms 11.295 ms 11.461 ms
5 ( 21.305 ms 33.034 ms 14.599 ms
6 ( 14.579 ms 13.753 ms 22.298 ms
7 ( 59.318 ms 68.201 ms 58.879 ms
8 ( 60.416 ms 59.890 ms 62.973 ms
9 ( 60.302 ms ( 60.768 ms ( 60.289 ms
10 * * *
11 ( 69.266 ms ( 62.532 ms ( 61.110 ms
12 ( 60.723 ms 63.999 ms 75.861 ms

I suspect packet/traffic shaping, but I'd gladly be wrong on that. Does anybody know if AT&T does packet shaping and, if so, is there something specific that flags it and/or a way to get the account/modem MAC address/whatever off the throttle list?

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Old 05-31-2009, 09:56 AM   #2
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do you run any other bit-torrent type programs, other than the blizz downloader?
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Old 06-01-2009, 07:19 PM   #3
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Thanks for the response.

I don't do any torrenting, and nor (I think) do the two others who share the connection--at least based on my (admittedly novice) interpretation of router logs.

Even my Blizz downloader is currently blocked: As a test, I've blocked all ports on the router above 600 (TCP and UDP) for every IP on the LAN except mine, and even ports above 6101 (TCP and UDP) for my IP. The router log isn't very detailed, so while I'm now seeing a few "packet denied" entries, it doesn't tell me which LAN IP or port is being blocked--it only shows souce and destination addresses for allowed packets, none of which look torrent-y.

After reading other posts here, it appears this approach is unlikely to work since--if someone *was* torrenting--apparently most clients look for an open port if defaults are blocked, and can even use port 80. Indeed, after two days I haven't noticed an improvement, despite repeated power-cycling of modem, router, computer and having several different assigned IPs.

Other possibly relevant bits:

A. Tried Skype with a guildmate yesterday. First time using since Vent problem started last week. Outgoing communication was clear and on-time for the first minute or so, then I started breaking up, and then Skype disconnected the call and kept doing so regardless who initiated. Not exactly the jumbled and heavily delayed transmits in Vent, but similar enough to be suspect

B. Now also seeing extremely variable lag in WoW. It started at the same time as the Vent issue, and seems different than typical lag in that it doesn't correlate with the ping repored by the game (consistently < 75ms) but *does* seems to get worse when I do stuff I assume would increase outgoing traffic (e.g. rapid chain-casting of spells during raids)

C. The traceroute to the guild vent server in my original post remains consistent, i.e. it still times out/gets stuck on hop 10, which lasts several seconds, but hops 11 and 12 don't reflect that delay. Also, hops 9 and 11 always have three addresses, but the rest are one address per hop. Not sure how to interpret this, but my guess is packets are held at hop 9 address(es) for several seconds before they are released to address(es) in hop 11.


1. Is there any conclusive test to determine packet shaping?

2. Does anybody know if AT&T DSL does packet shaping?

3. If yes to 2, does anybody know what triggers an account to be put on the packet shaping "blacklist"?**

4. Has anybody with AT&T ADSL had this happen and was able to resolve it (without changing providers)?

5. If yes to 4, what was done?

Thanks in advance for any assistance or advice you can provide. This is very frustrating!


** I'm assuming AT&T did not suddenly apply packet shaping to all ADSL accounts last week--I'd think there'd be some news if they had. Therefore, I'm assuming there is a blacklist, and some criteria for getting put on there. Getting a new IP doesn't fix the problem, which suggests the blacklist is tied to either the modem (based on MAC address?) or to the account.
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Old 06-02-2009, 04:53 PM   #4
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if multiple internet programs are experiencing issues, then it may be ISP related and could be temporary.
have you tried a speed test recently when the problem is occurring?
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Old 06-03-2009, 04:16 PM   #5
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Default tests to all US and international servers I tried fell within acceptable ranges: 1.8-2.55Mbps down, 0.20-42Mbps up, pings mostly between 18 and 100ms (Lahore, Pakistan was an outlier at 556ms :-).


Ventrilo and WoW worked fine last night after swapping out the crappy old Netgear WGR614 router for a shiny new Dlink DIR-825 dual-band wireless-N.

My original plan was to leave the router where it was, create a separate 802.11n/5GHz wireness network just for my MacBook Pro, and quarantine everyone else on the 802.11b/g 2.4GHz network. Unfortunately, the MBP Airport adapter is having trouble with the 5GHz band: slow/fails to detect, terrible range, high error rate, repeated disconnects--even when it is literally right next to the router. Preliminary research suggests the issue is with MBP Airport, and there may be a firmware fix. In the interim, I moved the router into my room and am just using Ethernet--very frustrating, having sank extra $$ for dual-band N. Fortunately, the new router does have much better 2.4GHz 802.11b/g range and (so far) nobody has complained about performance or objected to it being in my room and under my full control.

It also allows me to do some snazzy QoS prioritization. I'm prioritizing Ventrilo (6100UDP) and World of Warcraft (3724TCP) over all other traffic on my LAN IP, and prioritizing my IP over all others.

My tracerts don't look any different than before, and I'm not sure whether it was the QoS rules or using Ethernet (or something else) that did the trick...but at least it is working properly for the moment. This also suggests AT&T is NOT traffic shaping the connection--a great relief. Raising the issue with their tech support would (at best) be a long and agonizing escalation path, fraught with scripted assurances that "no, we don't do that sort of thing" and "your connection is fine but we can send out a tech".

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Old 06-03-2009, 07:19 PM   #6
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if you check back here i would suggest setting the QoS priority for vent to the tcp/udp port used to connect to your vent server.
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