Max speed?

iamenrique · 04-16-2009, 05:20 PM

Okay, at my fiance's house, they have SBC Yahoo DSL, I am not sure of the plan/speed they have. The wireless info says it has a connection of 54 mbps.

My question is, I realized that on her Macbook, when downloading files...the speed at which they download maxes out at 270 kbps whether using airport wireless connection or a cat5 ethernet cable(I did make the cable however...maybe i mixed something up?). Is this normal? It would seem to me that the ethernet connection should be faster than the wireless one. Could it be the max download speed imposed by the service, or what?

Also, if my network card tells me I have a connection of 54 mbps.... why is my download speed only 270kbps? It seems so slow. Especially when you consider the bandwidth of an ethernet cable.

**johnwill** · 04-16-2009, 05:22 PM

I really suspect that your Yahoo DSL is nowhere near 54mbit, more like 3mbit. I have a 20mbit connection, and I get full bandwidth on wired or wireless connections.

iamenrique · 04-17-2009, 04:51 PM

Well, I guess I still wonder why wireless and wired download speeds are the same. Logic to me would dictate that wired would perform better.

asgley · 04-18-2009, 07:24 AM

not really,

Net (2-3mbit)
Wireless (54Mbit)
Wired (100/1000Mbit)

where is the bottleneck?

Asg

**johnwill** · 04-18-2009, 02:01 PM

In the real world with real traffic, wired connections will perform better with less turn-around delay. That's because 802.11g connections are half-duplex and wired connections are full-duplex.

asgley · 04-19-2009, 05:03 AM

yeah but the latency added by the wireless connection is hardly noticeable by us humans, when its being used at less than 10% of its potential.
Asg

**johnwill** · 04-19-2009, 09:53 AM

The latency matters for some applications, gaming and VoIP come to mind. It's also the reason that file sharing over wireless links is far slower than wired links.

~~zerofire~~ · 04-19-2009, 09:40 PM

The maximum bandwidth of a connection is the maximum throughput of the slowest link. The DSL company limits connections to the net to the speed you pay for or the package you purchase. Both wired and wireless are going out to the net so the slowest link is that of your DSL line and not the connection to the router. Wireless and wired can be full-duplex and half-duplex depending on equipment. Most low end wire(1980's anyone?) and wireless (single antenna) devices and lines only support half-duplex. High end wire (common cat5e or cat6) and wireless (duel or triple antenna) devices and lines support full-duplex. Oh and before johnwill starts trying to rebuttal I have two words: waves bend.

**johnwill** · 04-20-2009, 06:51 AM

Actually, no matter how many antennas it has, it's still half-duplex. Even the latest wireless standard (that's still in draft 2), 802.11n, is half-duplex. The multiple antennas are actually for MIMO transmission/reception for better dead spot coverage and range. And the radio "waves" don't bend, but they do bounce off things.

zerofire, I suggest again you research some of the stuff you post before you post it.

~~zerofire~~ · 04-20-2009, 06:40 PM

MIMO is Multiple Input Multiple Output. This technique is coupled with the ability to have one antenna send a outbound signal while another receives an inbound signal. A antenna can be either receiving or sending but not both. By coupling two or more antennas to a wireless card it is capable of receiving and sending at the same time making it full-duplex. Waves can bounce off object but they also have the ability to bend around them to some degree. Thus two waves coming at each other can bend to avoid collision unlike signals coming from both sides of a Ethernet wire that meet. The two signals would cancel out because they can't avoid collision. That is high school physics of waves by the way.

**johnwill** · 04-21-2009, 07:28 AM

The fact that MIMO is used does not make the link full duplex. That's not the reason that MIMO is used. Since 802.11 in all flavors use a single channel band precludes simultaneous transmission and reception. If you think that 802.11n is full-duplex, I'd be glad to see a link stating that fact.

If you have a dual-channel router, they operate on two separate frequency bands. The D-Link DIR-855 is a typical example, it operates on both the 5.8mhz and 2.4mhz frequency bands. In this case, transmission and reception simultaneously is possible.

~~zerofire~~ · 04-21-2009, 04:51 PM

I don't see proof that it is half-duplex. What proof do you have that it is half-duplex and not full-duplex. Also you forgot to notice that a single channel band consists of multiple frequencies. Sending at the top frequency and receiving at the bottom frequency would cause very little signal degradation.

**johnwill** · 04-22-2009, 01:56 PM

These guys wouldn't be working so hard on a kludge to get full duplex from WiFi if the standard specification actually supported full-duplex. http://ieeexplore.ieee.org/xpl/freea...number=4753832

WiFi all along has been half-duplex, if 802.11n was indeed full-duplex, it would be widely advertised, since that's the major reason that SMB protocol transfers in wireless networks are so slow.

If you can find ANY source that states that any of the currently available WiFi protocols, 802.11a/b/g/n are full duplex, I'll gladly eat my hat.

04-16-2009, 05:20 PM	#1 (permalink)
iamenrique Registered User Join Date: Jan 2006 Posts: 59 OS: Vista x64	Max speed? Okay, at my fiance's house, they have SBC Yahoo DSL, I am not sure of the plan/speed they have. The wireless info says it has a connection of 54 mbps. My question is, I realized that on her Macbook, when downloading files...the speed at which they download maxes out at 270 kbps whether using airport wireless connection or a cat5 ethernet cable(I did make the cable however...maybe i mixed something up?). Is this normal? It would seem to me that the ethernet connection should be faster than the wireless one. Could it be the max download speed imposed by the service, or what? Also, if my network card tells me I have a connection of 54 mbps.... why is my download speed only 270kbps? It seems so slow. Especially when you consider the bandwidth of an ethernet cable.

04-16-2009, 05:22 PM	#2 (permalink)
johnwill Manager, Networking Forums Join Date: Sep 2002 Location: S.E. Pennsylvania, US Posts: 41,748 OS: Windows 7, XP-Pro, Vista, Linux Blog Entries: 1	Re: Max speed? I really suspect that your Yahoo DSL is nowhere near 54mbit, more like 3mbit. I have a 20mbit connection, and I get full bandwidth on wired or wireless connections. __________________ If TSF has helped you, Tell us about it! or Donate to help keep the site up! Microsoft MVP - Windows Desktop Experience

04-17-2009, 04:51 PM	#3 (permalink)
iamenrique Registered User Join Date: Jan 2006 Posts: 59 OS: Vista x64	Re: Max speed? Well, I guess I still wonder why wireless and wired download speeds are the same. Logic to me would dictate that wired would perform better.

04-18-2009, 07:24 AM	#4 (permalink)
asgley Registered User Join Date: Feb 2009 Posts: 105 OS: xp32, vista64, gentoo, rhle4, rhel 5 64, centos 64, debian, solaris, 2k3, 2k8	Re: Max speed? not really, Net (2-3mbit) Wireless (54Mbit) Wired (100/1000Mbit) where is the bottleneck? Asg

04-18-2009, 02:01 PM	#5 (permalink)
johnwill Manager, Networking Forums Join Date: Sep 2002 Location: S.E. Pennsylvania, US Posts: 41,748 OS: Windows 7, XP-Pro, Vista, Linux Blog Entries: 1	Re: Max speed? In the real world with real traffic, wired connections will perform better with less turn-around delay. That's because 802.11g connections are half-duplex and wired connections are full-duplex. __________________ If TSF has helped you, Tell us about it! or Donate to help keep the site up! Microsoft MVP - Windows Desktop Experience

04-19-2009, 05:03 AM	#6 (permalink)
asgley Registered User Join Date: Feb 2009 Posts: 105 OS: xp32, vista64, gentoo, rhle4, rhel 5 64, centos 64, debian, solaris, 2k3, 2k8	Re: Max speed? yeah but the latency added by the wireless connection is hardly noticeable by us humans, when its being used at less than 10% of its potential. Asg

04-19-2009, 09:53 AM	#7 (permalink)
johnwill Manager, Networking Forums Join Date: Sep 2002 Location: S.E. Pennsylvania, US Posts: 41,748 OS: Windows 7, XP-Pro, Vista, Linux Blog Entries: 1	Re: Max speed? The latency matters for some applications, gaming and VoIP come to mind. It's also the reason that file sharing over wireless links is far slower than wired links. __________________ If TSF has helped you, Tell us about it! or Donate to help keep the site up! Microsoft MVP - Windows Desktop Experience

04-19-2009, 09:40 PM	#8 (permalink)
~~zerofire~~ Troubled Join Date: Nov 2008 Location: United States Posts: 637 OS: Windows 95/98se/2000 Pro/XP Home, Pro, or MCE/2003 and 2008 Server Enterprise/7, Debian, Ubuntu My System	Re: Max speed? The maximum bandwidth of a connection is the maximum throughput of the slowest link. The DSL company limits connections to the net to the speed you pay for or the package you purchase. Both wired and wireless are going out to the net so the slowest link is that of your DSL line and not the connection to the router. Wireless and wired can be full-duplex and half-duplex depending on equipment. Most low end wire(1980's anyone?) and wireless (single antenna) devices and lines only support half-duplex. High end wire (common cat5e or cat6) and wireless (duel or triple antenna) devices and lines support full-duplex. Oh and before johnwill starts trying to rebuttal I have two words: waves bend.

04-20-2009, 06:51 AM	#9 (permalink)
johnwill Manager, Networking Forums Join Date: Sep 2002 Location: S.E. Pennsylvania, US Posts: 41,748 OS: Windows 7, XP-Pro, Vista, Linux Blog Entries: 1	Re: Max speed? Actually, no matter how many antennas it has, it's still half-duplex. Even the latest wireless standard (that's still in draft 2), 802.11n, is half-duplex. The multiple antennas are actually for MIMO transmission/reception for better dead spot coverage and range. And the radio "waves" don't bend, but they do bounce off things. zerofire, I suggest again you research some of the stuff you post before you post it. __________________ If TSF has helped you, Tell us about it! or Donate to help keep the site up! Microsoft MVP - Windows Desktop Experience

04-20-2009, 06:40 PM	#10 (permalink)
~~zerofire~~ Troubled Join Date: Nov 2008 Location: United States Posts: 637 OS: Windows 95/98se/2000 Pro/XP Home, Pro, or MCE/2003 and 2008 Server Enterprise/7, Debian, Ubuntu My System	Re: Max speed? MIMO is Multiple Input Multiple Output. This technique is coupled with the ability to have one antenna send a outbound signal while another receives an inbound signal. A antenna can be either receiving or sending but not both. By coupling two or more antennas to a wireless card it is capable of receiving and sending at the same time making it full-duplex. Waves can bounce off object but they also have the ability to bend around them to some degree. Thus two waves coming at each other can bend to avoid collision unlike signals coming from both sides of a Ethernet wire that meet. The two signals would cancel out because they can't avoid collision. That is high school physics of waves by the way.

04-21-2009, 07:28 AM	#11 (permalink)
johnwill Manager, Networking Forums Join Date: Sep 2002 Location: S.E. Pennsylvania, US Posts: 41,748 OS: Windows 7, XP-Pro, Vista, Linux Blog Entries: 1	Re: Max speed? The fact that MIMO is used does not make the link full duplex. That's not the reason that MIMO is used. Since 802.11 in all flavors use a single channel band precludes simultaneous transmission and reception. If you think that 802.11n is full-duplex, I'd be glad to see a link stating that fact. If you have a dual-channel router, they operate on two separate frequency bands. The D-Link DIR-855 is a typical example, it operates on both the 5.8mhz and 2.4mhz frequency bands. In this case, transmission and reception simultaneously is possible. __________________ If TSF has helped you, Tell us about it! or Donate to help keep the site up! Microsoft MVP - Windows Desktop Experience

04-21-2009, 04:51 PM	#12 (permalink)
~~zerofire~~ Troubled Join Date: Nov 2008 Location: United States Posts: 637 OS: Windows 95/98se/2000 Pro/XP Home, Pro, or MCE/2003 and 2008 Server Enterprise/7, Debian, Ubuntu My System	Re: Max speed? I don't see proof that it is half-duplex. What proof do you have that it is half-duplex and not full-duplex. Also you forgot to notice that a single channel band consists of multiple frequencies. Sending at the top frequency and receiving at the bottom frequency would cause very little signal degradation.

04-22-2009, 01:56 PM	#13 (permalink)
johnwill Manager, Networking Forums Join Date: Sep 2002 Location: S.E. Pennsylvania, US Posts: 41,748 OS: Windows 7, XP-Pro, Vista, Linux Blog Entries: 1	Re: Max speed? These guys wouldn't be working so hard on a kludge to get full duplex from WiFi if the standard specification actually supported full-duplex. http://ieeexplore.ieee.org/xpl/freea...number=4753832 WiFi all along has been half-duplex, if 802.11n was indeed full-duplex, it would be widely advertised, since that's the major reason that SMB protocol transfers in wireless networks are so slow. If you can find ANY source that states that any of the currently available WiFi protocols, 802.11a/b/g/n are full duplex, I'll gladly eat my hat. __________________ If TSF has helped you, Tell us about it! or Donate to help keep the site up! Microsoft MVP - Windows Desktop Experience Last edited by johnwill; 04-22-2009 at 01:57 PM.