Question about statistics

Hello, I'm new to wireless and I'm tryng to see if there are any tweaks I can do either in the client wireless software (SMC/ralink) or in the AP(Actiontec gt704) (I'm running in windows 2000) For now, I've left both set to 802.11 b/g mix.

Typical results I see are about 15-25 % receive crc errors, and on the transmit side 3-10% "frames tranmitted successfully after retry" and 1-5 % "frames fail to receive ACK after all retries" This last statistic seems to drop significantly if I set B/G protection to OFF in the client.

The wireless nic is the SMCWPCI-GM Mimo. I think the Actiontec may be the poorer performer of the two pieces of H/W. It runs very hot and I'm trying to get Verizon to replace it. The distance between the two is about 18 feet.

I'm running 64-bit WEP but no further authentification.

Thanks for any tips. Dave

Reply to
davexnet01
Loading thread data ...

snipped-for-privacy@yahoo.com hath wroth:

You'll get quite a slowdown in maximum speed if you leave the 802.11b compatibilty feature enabled. See max theoretical numbers at:

The good news is that the 802.11b compatibility performance hit only appears when an 802.11b device connects to the access point. The current crop of chipsets seem to be smart enough to ignore unconnected

802.11b packets. No clue if the Actiontec GT704 qualifies.

Retch barf puke etc. That's awful.

Well yes. That's because the access point has switched to 802.11b mode and is seeing all the 802.11g packets as corrupted garbage or noise. It can't decode 802.11g when in 802.11b mode. When operating, my guess is about 25-30% airtime devoted to 802.11b packets, which explains why about 1/4 of the arriving packets require retransmission. This is the way it used to be before the chipset makers cleaned up the compatibility mode.

You might see a dramatic decrease in errors and retransmissions if you enable wireless CTS/RTS flow control in the wireless router. That will prevent 802.11g clients from belching packets when the access point is in 802.11b mode, and the reverse. However, flow control will slow things down even more.

Doesn't matter. MIMO on the client end only works with a compatible MIMO router. As far as the wireless routers are concerned, it's an ordinary 802.11g client.

Yep. I think you need to borrow a more modernish wireless router and compare statistics. I think you'll find them less disgusting.

Reply to
Jeff Liebermann

Jeff, Thanks for answering my message. I've got further questions based on your response and my lack of understanding in wireless networks.

Would it be wise to set the AP and NIC to 802.11g only?

Why is the AP switching to 802.11 b? Because the retries are high?

What setting do you recommend then? What about the "B/G protection to OFF" setting in the NIC How should it be used? Placing it on AUTO gives all the retries while setting to off mitigates them somewhat.

I am unable to find this setting in the AP. There does seem to be something similar in the Nic config program

The replacement modem arrived today. It has an updated firmware, so I'm hoping for the best

Thanks again for your help. Unfortunately, at this point, I don't know enough about the subject to know if I even asking the right questions! Dave

Reply to
dave xnet

dave xnet hath wroth:

I keep running into 802.11b only clients all the time. For example, my fairly new Verizon XV-6700 cell phone only does 802.11b. So, I'm stuck with 802.11b compatibility mode on. I'm really tempted to install two access points, one for each mode so that the 802.11b stuff doesn't slow down the 802.11g traffic. You might try it temporarily off to see what it will do for your performance and error rate.

Why? Because some programmist told the AP to do it. In the bad old days, the AP would simply time slice between 802.11b and 802.11g. It would spend about 1/4 of it's time listening for 802.11b signals, which guaranteed a 25% speed reduction even if there were no 802.11b signals worth listening for. This was correctly judged as a really dumb way of doing this, so better algorithms were invented. The current fashion is to sample for 802.11b signals about once every 5 seconds. If it hears valid 802.11b data, it increases the sampling rate and window time depending on traffic. My guess(tm) is that your Actiontec GT704 is using something closer to the original algorithm.

I believe I recommended a few tweaks in my previous posting. Please don't make me re-read my own postings. I just hate doing that.

Dunno. It's the same issue as the access point. The client treats the other mode as noise or errors. Either way, they show up on the statistics as errors of sorts, while the radios just sit there waiting for data that will never arrive in a mode that you're not using. If all your wireless devices are 802.11g, then turn off 802.11b in literally everything, and the errors should evaporate.

It's usually called just "flow control". It's often next to "fragmentation threshold". I'm too lazy to read the manual and find the page.

It really shouldn't be in the NIC. In infrastructure mode, the access point runs the show and determines the protocols, channels, speeds, and such. The client radio just accepts whatever the access point delivers.

Is that another Actiontec GT704?

Reply to
Jeff Liebermann

This makes sense. However, in the gt704, I can find nothing relating to flow control at all. I have searched the 192.168.1.1 config pages, as well as the pdf manual. The only reference I can see in the manual is this sentence, in the 'features" section at the beginning: "Flow control support for Fast Ethernet"

Unfortunately yes. One things I could do is run it in Bridge mode and connect another router/AP to it.

Plenty of Netgear and similar ads. in the Sunday papers.

Thanks for your pointers! Dave

Reply to
dave xnet

That's a different from of flow control. The one I'm refering to is to reduce collisions and contention issues with the wireless part, not the ethernet. Another name for it is "RTS Threshold". It's usually right next to "Fragmentation Threshold". It's a manditory part of

802.11 and I have yet to see a wireless access point that lacks this feature. The WRT54G and DI-624:
formatting link
have it as "RTS Threshold".
Reply to
Jeff Liebermann

I can't find any sign of it. Perhaps it's hidden somewhere. There's really only two pages to the wireless setup in Verizon's gt704 Under basic I see: wireless on/off ESSID Channel # WEP on/off Select WEP key/Key length

Under Advanced I see: Security - choice of WEP, WEP+802.1x or WPA ESSID broadcast on/off Wireless MAC authorization

802.11b/g mode.

Thats' all I see. It's a mystery. Dave

Reply to
dave xnet

Cabling-Design.com Forums website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.