[Simon]

I'm playing around with a new 802.11n draft AP Extreme base station. Its WAN port is hooked up to my cable modem (ISP's limit is 10Mbps). It's running in the b/g compatible 2.4 GHz mode with DHCP and NAT. I'm using WPA2 Personal and MAC address filtering.

I have CD MB (not n capable) and a C2D MBP (n capable) sitting right next to each other about thirty feet away from the base station (two walls in between). According to the AP Utility, both get about -60dBm signal (it says the CD MB is running at 54, the C2D MBP at 130). So I'm assuming the C2D MBP is running in n mode, while the MB is running in g mode as you'd expect. All seems fine up to here.

The problem is that when I download something from the internet on the MBP I max out at about 4Mbps. The same download maxes out at about 10 Mbps on the MB (which corresponds to the cable modem's limit). This happens regardless of the web server and day time. At first I figured something might be wrong with the MBP installation or even hardware, but then I tried transferring files between the MB and MBP. In both directions I easily reached about 54Mbps which seems to correspond to the the max throughput of the MB. I went on to do the same with the MBP and another Mac that was hooked up to the AP Extreme through Ethernet. The transfer was even faster then (about 70Mbps).

So it seems my MBP's wireless card and antennas are working, but there appears to be a serious problem when the AP Extreme routs stuff coming from the WAN to the MBP - it should be doing 10Mbps and all I'm getting is 4Mbps. I'm wondering if it's a specific issue with 802.11n clients, because the CD MB accesses the WAN through the same AP Extreme at max speed (10Mbps).

Any ideas what could be going on here? Are there any known NAT/routing issues with the new AP Extreme base station and 802.11n clients? Is there any way to force the MBP to connect to the AP Extreme as a g device rather than as an n device?

[ghporter]

4Mbps is not a bad rate for NET data throughput with a GROSS MAX of 10Mbps. The cable company isn't telling you how much of that 10Mbps is overhead (not as much as DSL, but there is some), so 10 is a very gross number. And assuming you have a good signal level throughout the transfer, there is still a lot of overhead with WiFi. Getting 4Mbps ain't that shabby. The real test would be to measure throughput between the MBP and the MB-you should get a lot more than 4; I'd expect at least 12 and probably up to 30Mbps NET over a decent WiFi connection between the two.

[Simon]

Maybe my wording was unclear. I did test those things.
• I transfered data between the MBP and MB at roughly 54Mbps so obviously it maxed out the MB's 802.11g
• The MBP did no more than 4Mbps to the WAN repeatedly
• The MB right next to the MBP constantly reached 10Mbps to the WAN
• My ISP delivers those 10Mbps very reliably; the Mac hooked to up to the Expresse's LAN port gets the full 10Mbps and the MB did as well

It's only the MBP that's getting a mere 4Mbps. The other Macs are all getting 10Mbps. But those are either wired to the Express or 802.11g devices. That's why I'm guessing it's a problem when routing WAN traffic to 802.11n devices.

Is there a way to force the MBP to connect to the AP Express over 802.11g rather than n?

[Simon]

OK, I've played around with it some more. Everything looks really good with one exception. All traffic seems to max out the expected bandwidth except for the traffic between the WAN and the 802.11n capable MBP. Instead of getting the 10 Mbps that the cable modem supplies, it gets anywhere between 3-6 Mbps. Since I know other LAN clients are getting 10 Mbps I'm suspecting it's either the base station or the MBP. Since I also know the MBP can max out connections to other 802.11g clients, I'm guessing it's not just a MBP issue (like for example a bad antenna cable connection).

Does anybody here see another possibility than some kind of issue the new base station has with routing WAN traffic to 802.11n devices?

[Simon]

Or could this have to do with WPA2 being enabled? And if so, why would that slow down only the MBP but not the MB?

[ghporter]

I would expect only a lag from ANY form of encryption-any slowdown should be so insignificant that you wouldn't be able to see it. However, see what happens when you use basic WPA in this setup; there may be some sort of implementation issue with WPA2...

[Simon]

Originally Posted by ghporter 

However, see what happens when you use basic WPA in this setup; there may be some sort of implementation issue with WPA2...

Thanks, I'll try that.

But before I do that I'll try the new AirPort Base Station Update. I've already read reports that people have used it to update the firmware of their AP Extreme base station (n version) and have then seen substantially increased throughput. One guy claims (in somewhat cryptic language I'm afraid) before the update on his n base station he got basically half the throughput of his older g base station. After the update this issue has supposedly been mitigated.

[ghporter]

Post details! This sounds like a fix for some implementation of some function or other. This is good for all of us!

[Simon]

Well this is disappointing. The update only updates the AP Utility app but there's no actual firmware update for the base station. And of course the trouble my n-capable MBP is having with the new n base station is still there. I'll see if I find some time tomorrow to try the WPA2->WPA idea.

[Simon]

The problem just became even weirder. I noticed that the MBP sees the reduced throughput to the WAN (4 vs. 10 Mbps) even when it's hooked up to the base station through its LAN port rather than over 802.11n. So this is looking more and more like some kind of WAN routing issue between the base station and the MBP. I have absolutely no idea what's going on.

[ghporter]

Try a manually assigned IP and see if that changes anything. I'll bet it does. After that, try deleting your location and setting up a new one (or just setting up a new one using all the defaults if you are using an "automatic" location).

[Simon]

Thanks for those tips!

Originally Posted by ghporter 

Try a manually assigned IP and see if that changes anything. I'll bet it does.

No, unfortunately it didn't.

After that, try deleting your location and setting up a new one (or just setting up a new one using all the defaults if you are using an "automatic" location).

I set up a new location (since I'm always using automatic). Set it to use AP and DHCP. No dice. Set it to use AP and manual setting. Still no dice.

No matter what I do the fastest WAN transfers I see on the MBP are 5Mbps. Other Macs connected to the same base station consistently see 10Mbps w/o any problems.

Do you have any other suggestions? I'm completely clueless.

[ghporter]

Nope. I'm out of ideas too.

Maybe you could reinstall the AirPort drivers, but that's a real stretch.

[Simon]

Just to be sure, I'm gonna set up a new user account and log in as that user. I'll see if that changes anything. And finally, I'll have to borrow another rev B MBP and see if I can duplicate the issues on that box. This isn't making any sense to me at all.

Glenn, since you suggested creating a new location and using new settings I suppose you were targeting screwed up pref/plist files. Do you have a list of files that hold AP, network, and location settings. I'd like to delete them and set up everything from scratch just to rule out that possibility as well.

[brokenjago]

I've heard that the AP Extreme has serious problems with it's implementation of WAN in some situations.

Perhaps this is one of them?

[ghporter]

Originally Posted by Simon 

Glenn, since you suggested creating a new location and using new settings I suppose you were targeting screwed up pref/plist files. Do you have a list of files that hold AP, network, and location settings. I'd like to delete them and set up everything from scratch just to rule out that possibility as well.

Nope, sorry. I know that's what dumping a location and making a new one clears up, but as for the actual internals, I am still pretty sketchy about where things get stored.

I'm sure someone with a lot more time invested in the internals will see this and provide the info you need, but I'm still learning that sort of thing.

[Simon]

Well I set up a new user account. Tried everything there too but still no luck.

I'm out of ideas now. I still want to see if going to WPA, WEP, or nothing at all will make a difference. But I'm not expecting it. Even if I hook up the MBP directly to the base station with a 3 feet long Cat 5 cable I still can't get >5Mbps to the WAN.

[Simon]

I'm wondering if and when Apple will release a firmware update for the new base station...

[Simon]

Yesterday I tried once again to hook up the MBP directly to one of the AP Extreme's LAN ports and finally I managed to get ~9Mbps. I disconnected the Ethernet cable, tuned the MBP's AP back on, and did some more tests: they then consistently gave below 4.5 Mbps. And this was while the MBP was about three feet away from the base station and the AP Utility claimed it had a -45 dBm signal giving it a 130 Mbps connection. The MB two rooms away (-60dBm, 54Mbps connection according to AP Utility) was getting 10Mbps during the entire time.

[Simon]

I'll be damned! Simply turning off WPA2 solved the issue. Thanks for the tip, Glenn!

I initially removed all encryption (my network is still hidden and uses MAC address filtering) and immediately noticed I was getting 10 Mbps to the WAN even with the MBP. I turned on WEP (128 bit) and managed to retain the 10 Mbps. So I guess this is the setting I'll be using - at least until Apple gets their act together and fixes the WPA2 bug in the AP Extreme firmware.

I'm still amazed that the WPA2 issue only showed up with the MBP on the n connection. The MB on the g connection shows a consistent 10 Mbps to the WAN regardless of the encryption. Any ideas to explain this?

Finally, how safe is WEP? IIRC it has been hacked so I guess it's actually not 100% bullet proof. OTOH my delicate traffic goes through SSH tunnels anyway so I guess the AP encryption is mainly to prevent 'casual' monitoring of my general wireless traffic. Will WEP do that adequately? Until Apple fixes the WPA2 issues, I guess I'll be sticking with WEP unless that's considered entirely careless.

[ghporter]

WEP is horrible. It is almost trivially broken, in part because of a major flaw (that public scrutiny of the algorithm would have revealed in minutes) in the logic of it. Try WPA (not WPA2) and see if you retain your speed. WPA is exceptionally secure and robust, and it is computationally infeasible (nice geek talk, huh!) to break, so it makes your network very safe-as long as you use a good (random, long, no real words included) passphrase. I'm hoping that it's the WPA2 logic that's goobered up in the MBP N card, and that WPA (original) will work fine. If not, there are other workarounds that, though more trouble to set up and use, will provide security.

[Simon]

Well then I guess WEP is out the question.

I also noticed that the MB could no longer automatically connect to the AP Extreme when it was using WEP. My wireless network would show up in the AP menu, but the damn thing just wouldn't automatically connect (of course it was in the list of preferred networks and the setting was to automatically join those). You had to manually select the network from the AP menu. Then it ran fine. I trashed all of the plist files I could (fseventer is a godsend to find out which plist files are involved!) and still no dice.

So back to WPA and slow WAN transfer rates it is. I actually chose WPA/WPA2 rather than strict WPA2 (the new AP Utility doesn't have a 'only WPA' entry). The speed on the MBP is however identical to WPA2, roughly 4-6 Mbps. All other clients are doing just fine and getting 10 Mbps. I really hope Apple releases a firmware update for n hardware soon. This WPA bug is such a nuisance.

[ghporter]

Crap! That's disappointing to me-it must really irk you. I'll see what turns up in the form of VPN-like connection options to secure your network.

[Simon]

Originally Posted by ghporter 

Crap! That's disappointing to me-it must really irk you.

It does! First of all because I don't really understand what's going on and secondly because there's no decent workaround. I basically get to sit here, twiddle my thumbs, and wait for Apple to release the 'magic update'. Duh.

[Simon]

Success!

As soon as I saw the firmware update (version 7.1) this morning I downloaded and installed it. And look here, the WPA/WAN traffic issues are gone! The MBP can now download from the WAN with the full ISP bandwidth of 10 Mbps. Just like the 802.11g Macs and the Macs attached to the base station's LAN ports. I'm very glad Apple has fixed the WPA bug!

The only remaining thing to check out is if I can switch the whole network from WPA to WPA2 and retain the full speed. I'll try that when I get home form work. I'm guessing WPA2 should be preferred over WPA. Opinions?

[ghporter]

Hurray! Obviously someone was paying attention, noticed this problem and fixed it.

Now, WPA vs. WPA2. WPA2 is more secure than WPA. But to me the comparison is like getting blowed up by an A-bomb versus an H-bomb. You're way blowed up either way...

It is "computationally infeasible" to break WPA (assuming you've used a good passphrase) given a huge amount of computing power and taking a number of seconds that exceeds the lifetime of the universe. Really. A 'good passphrase' means one that is long and complex, but that does not include any real words-I use a 63 character passphrase generated by a decent randomizer (this one specifically). The only reported successful attack on WPA was one that broke the passphrase-to-key algorithm and was used against stupidly short and simple passphrases, so complexity is your friend.

From what I've read, WPA2 would take significantly more power and significantly more time to even begin to break.

So, if WPA is that good, more is better, right? Maybe. If everything you want to connect with is WPA2 capable, go for it. But anything that's is at least G capable will support WPA, so a mixed, "legacy" network would be secure if you used WPA, even if WPA2 is better.

[Simon]

And although there weren't many people discussing this issue in this thread here, obviously others were experiencing the same WPA/speed issues. But fortunately the 7.1 update has helped them as well.

In the meantime I've switched the entire AP network to strict WPA2 and it still is working just as good as with WPA after the 7.1 update. So in the end it seems all is fine again. I guess with really new products it sometimes just takes a while to get the software right. Although I am somewhat surprised that Apple didn't notice the issue earlier - isn't WPA and connections to a fast WAN a fairly common thing?

[ghporter]

Originally Posted by Simon 

And although there weren't many people discussing this issue in this thread here, obviously others were experiencing the same WPA/speed issues. But fortunately the 7.1 update has helped them as well. ...Although I am somewhat surprised that Apple didn't notice the issue earlier - isn't WPA and connections to a fast WAN a fairly common thing?

I think this has to have been a goof, not a bug. "Don't forget to take that instrumentation code out so we don't send out something that's really slow with WPA." "Sure, right after lunch!" Oops. As consistent as your problem was I can't believe that it was an algorithm problem.