Wireless and Gigabit

[futureal]

Hi,

I am, among other things, hosting a LAN party here at my house, and need to pick up one or more switches. Given that, I'm thinking now would be a good time to upgrade the home LAN to gigabit, since some of the larger switches (16/24 port) do not seem to be *that* much more expensive in gigabit than in normal 10/100.

Right now, things are configured via a cable modem -> wireless router/switch, with three computers connected directly to the switch and a couple more in other places in the house on 802.11g. What I would like to do is set it up so my 3 hard-wired computers are now on gigabit, but maintain internet through the wireless router.

I am assuming that I can take a gigabit switch, plug the computers into that, then plug that into the wireless router and everything will work as desired: the computers will communicate at 1000Mbps but (of course) internet traffic will be limited to 100Mbps as it is coming through the slower (10/100) switch.

Am I correct? Anything else I should think about in the process?

Thanks!

 

[SaigonK]

Originally posted by: futureal
Hi, I am, among other things, hosting a LAN party here at my house, and need to pick up one or more switches. Given that, I'm thinking now would be a good time to upgrade the home LAN to gigabit, since some of the larger switches (16/24 port) do not seem to be *that* much more expensive in gigabit than in normal 10/100. Right now, things are configured via a cable modem -> wireless router/switch, with three computers connected directly to the switch and a couple more in other places in the house on 802.11g. What I would like to do is set it up so my 3 hard-wired computers are now on gigabit, but maintain internet through the wireless router. I am assuming that I can take a gigabit switch, plug the computers into that, then plug that into the wireless router and everything will work as desired: the computers will communicate at 1000Mbps but (of course) internet traffic will be limited to 100Mbps as it is coming through the slower (10/100) switch. Am I correct? Anything else I should think about in the process? Thanks!

You are correct except that your cable modem is reall7y only 10mb or less...normally like 1-3mb.
Your 3 PC's on the Gig switch (and any others you add) would communicate at 1000MB, providing they are 1000MB client cards.
Going to the router, they would all funnel down to 100MB then out to the real world they would funnel down again to 1-3MB or so....

 

[gunrunnerjohn]

I think you also should look more closely at those gigabit 16-24 port switches. I think you'll find, unless you spend quite a lot more money, that they only have one or two gigabit ports, the rest being 10/100 ports.

 

[futureal]

I should have clarified that I was looking at 5/8 port gigabit switches versus 16/24 port regular switches. And I meant that those were comparable in price with each other.

Anyway, thanks for the advice. I ordered an 8 port switch from Newegg and I'm going to run with that for now.

 

[Cleaner]

Just my .02 but I recently upgraded my work's network backbone to gigabit and here is my experience with such. Unless the machines have massively fast RAID 5 arrays that can support sending 50-80MBps transmissions you won't get more than a spike over the regular speeds of 100Mbps. Only my fastest servers can run at the 1000Mbps speed for very long. The older servers just poke along at around 10/100Mbps speeds. The burst transfer rate is very good but the sustained rate of transfer is just average. Unless you have amazing hard drives and such the move to gigabit isn't worth it.

 

[gunrunnerjohn]

I agree. While I can read at around 25mbyte/sec vs. 9mb/sec with 100mbit, that's about the only speed boost I've seen with my gigabit NICs. Writing speed has hardly changed, maybe 15-20% faster, not nearly what I was looking for. All the machines are at least 2ghz with 7200RPM 8mb cache drives, and I'm kinda' disappointed.

 

[futureal]

The two main computers I transfer between here have 10K WD Raptor drives, so I am hoping to see a little bit of a performance boost between them. I transfer large files rather often. It's not that I couldn't get by with 100Mbps, I just figure if I am going to buy something, it might as well be newer technology rather than older.

Thanks for the input, though. It will be interesting to run some benchmarks on the network performance. Do you guys know of any such benchmarking tool?

 

[gunrunnerjohn]

I think you're going to find that the disk speed isn't the limiting factor, but rather the protocol overhead. When I benchmark my local disk drives, say a gigabyte copy from one to the other, I get between 35-40 mb/sec transfer speed. When I do the same function from another similar computer over the gigabit LAN, I get about 9 mb/sec writing to the remote system, and 20-25mb/sec reading from the remote system. I'm assuming that the SMB overhead in writing is causing the slow response when sending the file to the other side. I've tried this with TCP/IP only, NETBEUI only, and both protocols enabled, no significant change. I suspect you'll find that gigabit isn't going to buy you nearly what you think it will...

 

[BlitzRommel]

I notice a good difference from my fileserver ever since I got a switch with gigabit ports. And be sure to have a switch with jumbo frames support.

 

[Sideswipe001]

That's odd. I just upgraded my LAN to gigabit - mainly because I regularlly move up to 44GB of files inbetween computers for various reasons. It cut the time needed to transfer those 44GB between my two fastest computers from approx 3 hours to about 30 mins. Just for kicks I logged into my FTP over the LAN using download accelerator and watched it hit 800Mb/s download speed.

I'm very satisified with the move.

Oh, and Sisoft Sandra does have a network benchmark tool.

 

[gunrunnerjohn]

Tell me more about your systems, I'd love to see some real speed gains from the gigabit link...

 

[Sideswipe001]

Lets see -

System #1 is a Dual 2.8 GHz Xeon box with 2 GB of RAM. Asus PC-DL Deluxe is the motherboard, with onboard Gigabit (CSA based). That computer has 2 IDE 7200 RPM 8MB cache disks, in RAID 0.

System #2 isn't nearly as nice, but not bad. It's an AMD 2200+ on a Biostar M7NCD nForce2 chipset. It's got 3 GB of RAM. That computer is using a Linksys Gigabit ethernet card. Standard Maxtor 7200 RPM drive in that one, no RAID.

They are both hooked to a Netgear 5 port Gigabit switch by Cat-6 cabling.

Any other questions?

 

[gunrunnerjohn]

Originally posted by: Sideswipe001
Lets see - System #1 is a Dual 2.8 GHz Xeon box with 2 GB of RAM. Asus PC-DL Deluxe is the motherboard, with onboard Gigabit (CSA based). That computer has 2 IDE 7200 RPM 8MB cache disks, in RAID 0. System #2 isn't nearly as nice, but not bad. It's an AMD 2200+ on a Biostar M7NCD nForce2 chipset. It's got 3 GB of RAM. That computer is using a Linksys Gigabit ethernet card. Standard Maxtor 7200 RPM drive in that one, no RAID. They are both hooked to a Netgear 5 port Gigabit switch by Cat-6 cabling. Any other questions?

Well, I can't imagine why I have no significant performance gains. I have a 2.4ghz P4 with 7200RPM 8mb drives on this system, and an AMD 2400+ EPOX 8RDA with 7200RPM 8mb drives on the other system, W2K on both. I have the Intel gigabit cards, and an Edimax 5 port gigabit switch. The transfer speed is the same with or without the switch.

 

[Sideswipe001]

That's odd. I am using a different OS - XP on the Xeon machine and 2003 Server on the other - but I can't see that making much of a difference. The switch does report them both running at Gigabit, correct? I don't understand it either.

 

[gunrunnerjohn]

The difference here is you're running Windows Server on one end, that may well handle the write requests better than workstation. There has to be some basic difference...

 

[sxr7171]

Originally posted by: gunrunnerjohn

Originally posted by: Sideswipe001 Lets see - System #1 is a Dual 2.8 GHz Xeon box with 2 GB of RAM. Asus PC-DL Deluxe is the motherboard, with onboard Gigabit (CSA based). That computer has 2 IDE 7200 RPM 8MB cache disks, in RAID 0. System #2 isn't nearly as nice, but not bad. It's an AMD 2200+ on a Biostar M7NCD nForce2 chipset. It's got 3 GB of RAM. That computer is using a Linksys Gigabit ethernet card. Standard Maxtor 7200 RPM drive in that one, no RAID. They are both hooked to a Netgear 5 port Gigabit switch by Cat-6 cabling. Any other questions?

Well, I can't imagine why I have no significant performance gains. I have a 2.4ghz P4 with 7200RPM 8mb drives on this system, and an AMD 2400+ EPOX 8RDA with 7200RPM 8mb drives on the other system, W2K on both. I have the Intel gigabit cards, and an Edimax 5 port gigabit switch. The transfer speed is the same with or without the switch.

I'm not really sure but I remember reading that beyond the HD being a limiting factor the PCI bus becomes a limiting factor with PCI cards. I believe they are going to have to move to PCI express to fully support PCI gigabit cards. I believe that some of the motherboards with built-in gigabit ethernet use some sort of proprietary connection directly to the chipset, but I'm not sure.

I think the problem results from the Hard Drives taking PCI bus bandwidth (assuming that even motherboard mounted IDE controllers use PCI bandwidth) and that bandwidth needs to be shared with the Gigabit card also. Add overhead on all the information flow on the PCI bus and I guess that might explain the performance you're seeing. However this hypothesis is based on certain premises that I'm not sure are true (IDE takes PCI bandwidth etc.).

 

[gunrunnerjohn]

All I know is performance is disappointing.

I don't think it's a bus bandwidth issue, but rather a protocol or handshake issue. If I read from the remote machine and write to my local machine, I get 25mb/sec file transfers. If I "push" the same file to the remote machine, the speed drops to around 10mb/sec. There is obviously some protocol issue I don't fully understand that limits my remote writing speed. I'm guessing it's some overhead in the SMB protocol, but I don't know the internals nearly well enough to figure it out.