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The Graveyard - Products No Longer Supported => Routers / COVR => DIR-825 => Topic started by: bbear on January 10, 2010, 09:55:10 PM

Title: DIR-825 with Linksys WUSB600N-CA V2 - slow speed in 5Ghz N mode
Post by: bbear on January 10, 2010, 09:55:10 PM

I have owned my DIR-825 for a few weeks now and have been very happy with it's wired Ethernet and Wireless-G performance and stability.

I set out to find a B2 h/w version of Dlink's DWA-160 USB adapter, I wanted this particular h/w version as I had read of problems with the A1/A2 version when used with Linux (32bit Jaunty). After three weeks of searching many stores in my local and surrounding area I gave up. Instead I went out and bought the Linksys WUSB600N V2 which I had read has the same ralink chipset.

I have got this *working* with my DIR-825 in 5ghz wireless-N mode but am am disappointed by the data transfer rate. At the moment I have a 100% signal strength due to both pieces of equipment being in the same room.

I timed the copy of a 3GB file from my windows box to my Linux box, it took over 15mins. I then installed the WUSB600N on another windows box and did a copy from one windows box to the other, it took 16mins. This is about 1/2 the speed which I have read others achieve when using 5Ghz wireless-N

I have read on the Linksys forums of others users experiencing slow wireless-n speeds so I suspect the problem is with the WUSB600N, I read of one solution but it requires me to select CH11 on my router. The problem is that my DIR-825 does offer me CH11, the channels available are:

CH36, 40, 44, 48, 149, 153, 157, 161

I don't yet know how critical it is to the WUSB600N to set CH11

I wondered if there was anyone out there who is using the DIR-826 in 5Ghz wireless-n mode who can tell me what is a reasonable data transfer rate to expect?

Also, if anyone knows how I can set CH11 in 5Ghz mode I would be very grateful,

thanks in advance for your help.

Title: Re: DIR-825 with Linksys WUSB600N-CA V2 - slow speed in 5Ghz N mode
Post by: rickm1350 on January 11, 2010, 01:38:13 AM

transferring a 3 GB file in 15 minutes doesn't seem too bad, that's a big file your moving.

Title: Re: DIR-825 with Linksys WUSB600N-CA V2 - slow speed in 5Ghz N mode
Post by: HTLuver on January 11, 2010, 09:41:52 AM

I also am having problems with network speed with the DIR-825.  My adaptor is Anthos 5009.  I'm trying to stream from a usb drive attached to the router.  My max speed i can achieve right now is ~20-25Mb/s @ 5.0Hz  :(.  It says i'm on a 130Mbps connection! This causes HD content to stutter horribly.  I haven't found the reason for the slow ass speed.  Even when connected to the router via ethernet cable the playback is jittery so i'm at a loss of words  ???.

Title: Re: DIR-825 with Linksys WUSB600N-CA V2 - slow speed in 5Ghz N mode
Post by: Hellbore on January 11, 2010, 10:04:18 AM

Quote from: bbear on January 10, 2010, 09:55:10 PM

I have got this *working* with my DIR-825 in 5ghz wireless-N mode...

...I have read on the Linksys forums of others users experiencing slow wireless-n speeds so I suspect the problem is with the WUSB600N, I read of one solution but it requires me to select CH11 on my router. The problem is that my DIR-825 does offer me CH11, the channels available are:

CH36, 40, 44, 48, 149, 153, 157, 161

Not actually a problem, just the way channels work.  No router in existence will let you select channel 11 on the 5GHz spectrum, because that wouldn't even make sense.  The channels correspond to different frequencies and 11 is the highest standard North American channel for the 2.4GHz band, whereas the 5GHz band starts at 36.  

If you need to use channel 11 to make your adapter work right, just set the 2.4GHz interface to channel 11 and use 2.4GHz instead of 5GHz.  

Title: Re: DIR-825 with Linksys WUSB600N-CA V2 - slow speed in 5Ghz N mode
Post by: bbear on January 11, 2010, 12:31:50 PM

My Linux box says I am on a 270Mbps connection and for the 3Gb file (actually 3,171,422,212/23.625 bytes) I calculated that a 908 seconds to transfer the file, that works out to be 3.49 Mbytes per second, which equals 27.92 Mbits per second

As for my Windows to Windows transfer, I need to double-check what bitrate it thinks it is connected. Also for my windows->windows test, the equipment was much further away and it only showed two bars (That'l trust me to believe manufacturers claims that wireless-n has greater range that wireless-G!)

It is hard to tell if the slow speed is a problem with the DIR-825 (or my configuration of it) or the Linksys WUSB600N V2 adapter. Or perhaps my expectations are too high and ultimately I am going to give up on the idea of using wireless to stream HD video around my house.

Quote from: HTLuver on January 11, 2010, 09:41:52 AM

I also am having problems with network speed with the DIR-825.  My adaptor is Anthos 5009.  I'm trying to stream from a usb drive attached to the router.  My max speed i can achieve right now is ~20-25Mb/s @ 5.0Hz  :(.  It says i'm on a 130Mbps connection! This causes HD content to stutter horribly.  I haven't found the reason for the slow ass speed.  Even when connected to the router via ethernet cable the playback is jittery so i'm at a loss of words  ???.

Title: Re: DIR-825 with Linksys WUSB600N-CA V2 - slow speed in 5Ghz N mode
Post by: bbear on January 11, 2010, 12:34:36 PM

Hellbore,
thanks for the info. The poster to the Linksys forum didn't make it clear that they were talking about the 2.4Ghz band. For the 5Ghz band perhaps they have a similar optimum router setting for their adapter. I will post back here if/when they get back to me.
 

Quote from: Hellbore on January 11, 2010, 10:04:18 AM

Not actually a problem, just the way channels work.  No router in existence will let you select channel 11 on the 5GHz spectrum, because that wouldn't even make sense.  The channels correspond to different frequencies and 11 is the highest standard North American channel for the 2.4GHz band, whereas the 5GHz band starts at 36.  

If you need to use channel 11 to make your adapter work right, just set the 2.4GHz interface to channel 11 and use 2.4GHz instead of 5GHz.  

Title: Re: DIR-825 with Linksys WUSB600N-CA V2 - slow speed in 5Ghz N mode
Post by: Hellbore on January 11, 2010, 12:40:08 PM

Quote from: bbear on January 11, 2010, 12:34:36 PM

Hellbore,
thanks for the info. The poster to the Linksys forum didn't make it clear that they were talking about the 2.4Ghz band. For the 5Ghz band perhaps they have a similar optimum router setting for their adapter. I will post back here if/when they get back to me.
 

You could maybe try channel 40, just a long shot but you could try it.  I read that some devices do best on this channel since it equates to exactly 5.2GHz. 

You could also try adjusting the beacon interval and fragmentation threshold, that helps some people.

Oh one thing to watch out for, make sure that for wireless N you are using WPA2-PSK with AES encryption, not TKIP.  Some devices will absolutely not get wireless N speeds unless using WPA2-PSK with AES.  My laptop is like that.

Title: Re: DIR-825 with Linksys WUSB600N-CA V2 - slow speed in 5Ghz N mode
Post by: bbear on January 12, 2010, 11:24:39 AM

Hellbore,
I tried CH40 but it didn't help. I have not tried changing the beacon interval or fragmentation threshold yet.

Before I do that I wanted to mention that using Wireshark on my Linux box I have identified a difference between using wired and wireless-n connection. For the wireless-n result, Wireshark reports 'TCP Retransmission' events corresponding to each time I get the audio glitches when streaming AAC from my Windows share.

I read many articles on the web discussing wireless links and how TCP Retransmissions cause big problems due to the time it takes to recover (often seconds). The question is - why are these TCP Retransmissions happening?

It is hard to believe it could be congestion on my wireless network as my Linksys WUSB600N V2 adapter and my Dlink DIR-825 are in the same room. My Linux box reports a 100% connection, connected at 270Mbps

I did read about problems with using a samba share on a Vista box (IPV6 related) but I am running XP Pro on my Windows share.

Does anyone have any ideas?

I just wish I could find a h/w revB version of Dlink's DWA-160, then at least I would be using all Dlink equipment. Dlink support might be more prepared to help me then.

Title: Re: DIR-825 with Linksys WUSB600N-CA V2 - slow speed in 5Ghz N mode
Post by: bbear on January 12, 2010, 05:04:56 PM

I have been doing quite a bit more investigation and are beginning to wonder if the problem is with the ralink rt3572 drivers for Linux or my Linux installation itself. Here are some reasons why I say that:

Using Wireshark on my Linux box, I monitored the packets going between my Linux box and my Windows share (XP Pro machine). When using wireless-n, every time I hear glitches in the streaming AAC audio it corresponds to "TCP Retransmission" events reported by wireshark

network-manager on my Linux box says that there were zero receive errors, zero transmit errors and zero collisions!

When I use a 1Gbps wired Ethernet there are no audio glitches and Wireshark does not report any TCP Retransmission events.

I installed the XP drivers for the Linksys WUSB600N V2 on my kids XP Home box. It is a long way from my DIR-825 so it connects using 5Ghz band with only two bars, at 40.5Mbps. However, I am able to stream the same AAC audio file from the same Windows share (XP Pro box) without any problems whatsoever.

I have read that TCP Retransmissions are a big problem when using wireless links as they take a long time to recover from (a couple of seconds), this ties in with the audio glitches I am hearing.

Maybe this is not a problem with the WUSB600N V2 or the DIR-825??

I am concerned now that even if I were to get hold of a rev B DWA-160 adapter that it would have the same problems since it uses the same ralink chipset.

Title: Re: DIR-825 with Linksys WUSB600N-CA V2 - slow speed in 5Ghz N mode
Post by: HTLuver on January 19, 2010, 06:21:29 AM

I finally got a spare computer from work to test the wireless connection between the router and two computers (one wired and one wirelss).  After alot of tinkering I was finally able to get a sustained 70Mb/s transfer speed with a peak of 80.  In one review the DIR-825 was getting ~80Mb/s throughput.  But in other reviews and a few members on this forum they say up to 110Mb/s ???  How are they achieving another 30-40 Mb/s.  Could it be my adaptor versus theirs?  I have security off with MAC filtering on.  Guess i'll just be happy i can achieve ~70Mb/s.  As a side note i was able to achieve 250-350Mb/s wired between computers.

Title: Re: DIR-825 with Linksys WUSB600N-CA V2 - slow speed in 5Ghz N mode
Post by: soso2565 on January 19, 2010, 03:24:33 PM

TO BBEAR:

You might consider to look your internal speed on your drive it self the connect might be able to get 270Mbs but have you look you drive

download that file ( zip )
and follow those info :

DiskBench

The program is using the current filesystem to save a file. If it is fragmented, the performance will be degraded, as it is in real life.

So, to figure out how fast your computer is, you can copy a file from A to B and use a stop watch.

Or you could just as easy use this program.

All it does is:
1) copies a file from A to B, times the time it took, and deletes the file from B again.
- or -
2) The other way to benchmark is to choose Create File. This way it just creates a file (consisting of a repeated 128 byte string). So if you only have one harddisk, this is the optimal test for you.



http://www.stephansauve.com/filess/app/DiskBench.zip (http://www.stephansauve.com/filess/app/DiskBench.zip)

Title: Re: DIR-825 with Linksys WUSB600N-CA V2 - slow speed in 5Ghz N mode
Post by: bbear on January 20, 2010, 01:00:46 PM

soso2565,
many thanks for the suggestion. I had ruled out the drive speed on my Windows box previously as I am able to play the same AAC audio files on my Linux box, streaming from my Windows box perfectly fine IF I use 1Gbps wired connection to my DIR-825.

Using the wired connection I have no audio problems whatsoever and Wireshark on my Linux box does not report any TCP Retransmission events.

I guess that the average data transfer rate may be ok, but perhaps there is a problem of latency. Perhaps there are occasions where the delay for the ACK coming back from my windows box to the TCP layer running on my Linux box is too great and then this triggers the retransmission event. A fragmented drive might do that. And perhaps as the wireless-n connection is that bit slower, this only comes to light when using the wireless connection.

One thought I had was to try using a NAS, but I don't have on and are not about to go out and buy one just for this experiment.

There is also Dlink's shareport, but there only appears to be drivers for Windows and Mac. (I am checking with Dlink support now to see if it is possible to use shareport with Linux). Also, I am not sure how fast shareport is, but it would definitly be worth trying if I can as it will rule out the Windows box.

Title: Re: DIR-825 with Linksys WUSB600N-CA V2 - slow speed in 5Ghz N mode
Post by: bbear on January 28, 2010, 08:57:07 AM

soso2565,

I had to move some files around to other drives so that I could defragment the drive from which I was streaming the AAC audio files. The disk was very fragmented but unfortunately defragging it made no difference.

I have not run a benchmark yet but I don't think the performance of the drive in my XP machine, or the machine itself could be a problem. The reason I say that I say that is because using a 1Gbps wired Ethernet instead of the wireless it works fine. No audio glitches, no TCP Retransmission events.

Also, a while back I did a test, transferring a large file over the wireless n connection, I used my stop watch to time it:

File size: 3,171,522,212 bytes

Time it took to copy the file from my windows share (cp windows_share/big_file . ) was 908 seconds

This equates to 3,171,522,212/908 = 3.49 Mbytes per second

Next, I copied over the same file but using the wired 1Gbps Ethernet connection:

Time taken to transfer file: 190 seconds

This equates to 3,171,422,212/190 = 16.7 Mbytes per second

Since I am only trying to stream AAC audio, the 3.49 Mbytes per second should be more than adequate, so I don't think that the performance of my XP machine or the hard drive in it is the problem

Title: Re: DIR-825 with Linksys WUSB600N-CA V2 - slow speed in 5Ghz N mode
Post by: lotacus on January 28, 2010, 09:36:02 AM

I havn't benched the dir-825 yet. I used to see this with the 655. Most times it was less than a 10Mb wired connection. Which I suppose would mean that over 80 percent of the wirless bandwidth was re-tranmissions.

Title: Re: DIR-825 with Linksys WUSB600N-CA V2 - slow speed in 5Ghz N mode
Post by: bbear on January 28, 2010, 12:37:40 PM

lotacus,

sorry to be slow on the uptake, forgive me but I am relatively new to wireless and struggling to understand it's limitations.

Why do you say that 80% of the wireless bandwidth was re-transmissions?

Ignoring the big (3Gb) data transfer for now, when I try to stream AAC audio why would there need to be any re-transmissions?

Here are the details on one of the AAC audio files I am trying to stream (audio player on my Linux box, pulling the file from my Windows XP box (samba)) ..

Size: 4.33 MB (9% of original, 10 to 1 compression)
Original Size: 46.55 MB
Length: 4 minutes 36 seconds
Channels: 2 (stereo)
Sample Rate: 44.1 KHz;
Sample Size: 16 bit
Bit Rate: 128 kbps
Encoder: AAC (LC)
Encoder Settings:
Audio Quality: Medium (Lossy)

This is a very small amount of data to transfer over a 4min 36second period. Why with a 5g 270Mbps wireless n connection should I see any TCP Restransmission events?

I don't believe that I have any sources of interference or other wireless n networks which could be causing collisions. Also, on my Linux box it confirms there were no receive or transmit errors and no collisions.

These TCP Retransmissions are an absolute killer for my streaming media center, every time it happens my audio cuts out for 2 seconds. Retransmissions seem to be a well documented concern for TCP over a wireless connection. Somehow I need to find out how to avoid them otherwise my wireless n gear will likely end up in the trash  :(

Title: Re: DIR-825 with Linksys WUSB600N-CA V2 - slow speed in 5Ghz N mode
Post by: bbear on April 14, 2010, 01:31:03 PM

I have solved the issues with audio drop out when streaming AAC audio from my Windows XP box to my Linux box. There were a number of issues, none (to my knowledge) were caused by my DIR-825.

Problem 1: network-manager in Linux doesn't get on well with the ralink driver. Tons of IO_CTRL messages are output to the /var/log/messages file every couple of minutes, and at the same point the wireless link is dropped momentarily by my Linksys adapter.

Solution: install wicd (an alternative network manager) on my Linux box

Problem 2: Even with the above problem fixed, I still saw occasional (every 20 to 30mins) drop-out. Using Wireshark (network monitor/sniffer) I tracked it down to my XP box flushing the ARP table. I read that in XP the default is for Windows to flush the ARP table if the network doesn't respond for 3 mins.
Using Wireshark I could see that there were pauses in the network traffic for three seconds, but could not discover the reason why. As far as I could tell, for every REQ there was an ACK and the packets looked ok. It is as if the audio streaming on my Linux box stops requesting data across the wireless network for a awhile as it already has enough data in it's bufffer. This is just a guess - I don't really know what is causing it.

Solution: set up wicd on my linux box to run a script which pings my XP box every 2 seconds.

Now, what would be a nicer fix would be to somehow stop my Windows box flushing the ARP table ('static' table?). I don't know enough about this ARP flushing stuff to tackle this unfortunately.