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Parja
EVDO Newbie
Joined: 27 Apr 2008
Posts: 9
Location: Whitewater, WI
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 Posted: Wed Feb 18, 2009 4:07 pm Post subject: |
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| reggie14 wrote: | | It's not even that (and the OP realizes that). The 802.11g protocol falls apart on paper at speeds above 54mbps. That in no way means it's physically possible, even under ideal conditions, to get 54mbps out of wireless g devices. |
Yup, even in the best of cases, 54mbps is the maximum bandwidth of the connection, not the actual data transfer rate. A chunk of that bandwidth is going to get eaten up with network protocol data...a particularly significant chunk if you're running any kind of security (and who isn't?).
| Quote: | One last comment to the OP: In most cases, you don't see reliability problems with wifi unless you do something that's high-bandwidth and not very tolerant of late/lost packets. Streaming high-definition video falls in this category. Wireless-N has plenty of bandwidth to stream high-definition video, and on average you'll have at least 3 times as much bandwidth as you need. But, every now and then they will be a hiccup. You can see this if you do a large file transfer over wifi and you watch a graph of bandwidth usage. For 802.11g you should be able to pull down 20mbps, but every minute or so it might drop down to 10mbps for a very short period of time. With a file transfer you would never notice this. But, even very short hiccups while streaming HD will empty buffers and cause a blip in playback.
Still, I think it's a great idea to switch from a wireless-g to a wireless-n bridge. You probably wouldn't notice any problems unless you stream blu-ray rips or other very high bit-rate videos (possibly including 1080i mpeg2 files). I'm not sure what kind of files you'd be dealing with, but I'm guessing they would be lower bit-rate mpeg4/H.264 files. Those shouldn't give you any problems. |
Yup, I'm sure I'll have some glitches now and again, but then again, I just put a 320GB hard drive in my PS3, so in most cases, I'll probably just download stuff to the hard drive before watching. This way, I just won't have to wait as long for the download. |
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reggie14
EVDO User
Joined: 09 Aug 2008
Posts: 29
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| Posted: Wed Feb 18, 2009 9:03 pm Post subject: |
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| Parja wrote: |
Yup, even in the best of cases, 54mbps is the maximum bandwidth of the connection, not the actual data transfer rate. A chunk of that bandwidth is going to get eaten up with network protocol data...a particularly significant chunk if you're running any kind of security (and who isn't?).
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Since I work in the security field (in cryptography, specifically), I want to clarify something here. WPA encryption (and I won't mention WEP, since you better not be using it), doesn't add any significant amount of overhead. Encrypted information typically isn't (much) bigger than the unencrypted data. There is some overhead to establish a key when you first connect to an AP, and a little overhead to rekey every once in a while, but isn't not very much. Years ago turning on encryption used to limit throughput because of the extra computations. This was a problem with WEP and WPA-TKIP because encryption was performed on the router's main processor. Now processors on routers are faster, so it's less of a problem. And, everyone should really be using WPA2-AES. As far as I know, AES is always performed on a special chip off the main processor, because it's a much more taxing (and secure) encryption algorithm than the one used in TKIP. So, turning on WPA2-AES encryption shouldn't have a terribly noticeable effect on newer wifi routers.
As far as I know, the speed limitations in wifi are due to the way the protocol works. There is some overhead in the form of packet headers, but it's not that much. I think its ~40 bytes for each packet, which can have ~1500 bytes of payload data. I think the bandwidth limitation is mainly from the way wifi works. Before you send a packet, first your wifi card listens for a while to make sure someone else isn't transmitting. Once it's "safe", it transmits one packet, then waits again before sending the next. Unlike ethernet, where the network card can detect if two computers talk at the same time and interfere with each other, wifi cards can't tell until they notice the receiving device never confirms it received a particular packet. And, of course, lost packets can drag down bandwidth quite a bit due to retransmission costs. |
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im_electronic
EVDO Junkie
Joined: 27 Aug 2009
Posts: 191
Location: Covina, CA
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| Posted: Fri Oct 02, 2009 6:30 pm Post subject: |
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A WRT350 or WRT310 from linksys flashed with DD-WRT can be put into a client bridge mode and will have gigabit available, in this mode you can also assign the WAN port to the switch, making it a 5 port gigabit wifi N bridge.
I have both and have been there, done that, btw. and can walk you through it. |
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