gigabit nic advice

[Rutkus]

i am thinking about buying a gigabit NIC to upgrade my network card, i'm currently running a built in 10/100 nic on my abit nf7-s motherboard and i have a cable modem connection. i also have a small network in my house. however before i do this i had a couple of questions to see if it is worthwhile.

i have 4 computers connected to a linksys befsr41 router and that is connected to my cable modem.

#1 what is the best quality gigabit nic?


#2 will i see an increase in speed surfing the web?


#3 will i see an increase in speed exchanging files between computers?


#4 will i need to upgrade my rounter to get the full benefit of the upgrade?

thanks in advance

 

[larva]

i am thinking about buying a gigabit NIC to upgrade my network card, i'm currently running a built in 10/100 nic on my abit nf7-s motherboard and i have a cable modem connection. i also have a small network in my house. however before i do this i had a couple of questions to see if it is worthwhile.

i have 4 computers connected to a linksys befsr41 router and that is connected to my cable modem.

#1 what is the best quality gigabit nic?

Doesn't much matter if you are going to place it on the regular 32bit 33MHz PCI bus.

#2 will i see an increase in speed surfing the web?

No.

#3 will i see an increase in speed exchanging files between computers?

No.

#4 will i need to upgrade my rounter to get the full benefit of the upgrade?

No, you will need to upgrade the router to see any benefit. And as gigabyte switches are still wicked expensive, the limited benefits that buying such a device for your application don't make the expenditure make a lot of sense.

 

[PAWO]

All your PC's would have to be Gigabit equipped as well as your router (or switch), the advantage would only become present with VERY large file transfers, and then the hard drive speed becomes a limiting factor as well as the 32 bit PCI bus, it would provide essentially no advantage at all.

 

[Rutkus]

i see, so its not worth it. ok just caught a bit of an upgrading bug and thought that would help. thanks for the info!

 

[NiTrO bOiE]

On the screensavers they actualy did a side by side test of 100 vs gigabit. The gigabit was only about 4 seconds faster.

 

[su root]

No or very little benefit? I think not...

Currently, network transfers are capped at about 8-10megabytes/s out of a possible 12.5 that 100Mbit gives you.

With gigabit, it's 120Megabytes/s that's the cap.
Your PCI bus, at 32 bits wide * 33 MHz = around 132Mbytes/s.
Your IDE bus, assuming it's ATA/66, is 66Megabytes/second.
If you have a board with ATA/100 or 133, they're 100Mbytes and 133Mbytes/s.
Most harddrives bench around 20+Megabytes/second sequential read, and sequential write

Those are the numbers behind it. Assuming both systems are running those minimum specs with ATA/66, then in a fully gigabit network (CAT6 cables, gigabit NICs, and a gigabit switch) your speeds would only be limited by the speed of your harddrives.

That's theoretical. In practice, you'll get about a 100% increase, to 20Mbytes/second, on average. If you have RAID in one or both systems, or faster harddrives than the average, then you'll get better speeds. The highest I've seen over copper is 500Mbits/second, (62.5Mbytes/s) pushed/pulled from several clients. After that, your looking at fibre because copper sucks for attenuation.

 

[DaBigJ]

No or very little benefit? I think not...

Currently, network transfers are capped at about 8-10megabytes/s out of a possible 12.5 that 100Mbit gives you.

With gigabit, it's 120Megabytes/s that's the cap.
Your PCI bus, at 32 bits wide * 33 MHz = around 132Mbytes/s.
Your IDE bus, assuming it's ATA/66, is 66Megabytes/second.
If you have a board with ATA/100 or 133, they're 100Mbytes and 133Mbytes/s.
Most harddrives bench around 20+Megabytes/second sequential read, and sequential write

Those are the numbers behind it. Assuming both systems are running those minimum specs with ATA/66, then in a fully gigabit network (CAT6 cables, gigabit NICs, and a gigabit switch) your speeds would only be limited by the speed of your harddrives.

That's theoretical. In practice, you'll get about a 100% increase, to 20Mbytes/second, on average. If you have RAID in one or both systems, or faster harddrives than the average, then you'll get better speeds. The highest I've seen over copper is 500Mbits/second, (62.5Mbytes/s) pushed/pulled from several clients. After that, your looking at fibre because copper sucks for attenuation.

rgr.

 

[larva]

No or very little benefit? I think not...

Currently, network transfers are capped at about 8-10megabytes/s out of a possible 12.5 that 100Mbit gives you.

With gigabit, it's 120Megabytes/s that's the cap.
Your PCI bus, at 32 bits wide * 33 MHz = around 132Mbytes/s.
Your IDE bus, assuming it's ATA/66, is 66Megabytes/second.
If you have a board with ATA/100 or 133, they're 100Mbytes and 133Mbytes/s.
Most harddrives bench around 20+Megabytes/second sequential read, and sequential write

Those are the numbers behind it. Assuming both systems are running those minimum specs with ATA/66, then in a fully gigabit network (CAT6 cables, gigabit NICs, and a gigabit switch) your speeds would only be limited by the speed of your harddrives.

That's theoretical. In practice, you'll get about a 100% increase, to 20Mbytes/second, on average. If you have RAID in one or both systems, or faster harddrives than the average, then you'll get better speeds. The highest I've seen over copper is 500Mbits/second, (62.5Mbytes/s) pushed/pulled from several clients. After that, your looking at fibre because copper sucks for attenuation.

My point was that an effective increase in transfer speed from ~10MB/s to ~20MB/s for a home network in no way competes with the cost of implementing a gigabit architecture. Perhaps if you got an order of magnitude improvement, or if you were actually seriously constrained by 100Mbit performance levels the expense would make sense, but for the type of home use this poster inquired about it makes absolutely none.

 

[cphastings]

Gigabit ethernet won't help your Internet Speeds either because your Cable Modem is probably capped off at 10 mb/s going in and out anyway. If you had a Cable Modem that did 100 mb/s in and out and your whole network is 100 mb/s than that would probably help. However I do think that Cable companies are charging an arm and a leg for that service.

 

[Albuquerque]

A lot of people talk about bandwidth as if the only thing you're transferring is a file. You don't transfer a single file, you transfer hundreds of thousands of individual data packets. Each packet holds a very small amount of your data, and also has a VERY small amount of header information.

In a TCP/IP setup, each packet that is sent must ALSO be acknowledged by a "receipt" packet. Until your machine gets the receipt back, it doesn't send the next one. You aren't "streaming" data on your home network, you are establishing a two-way session with the remote computer (even if it's sitting on the same desk plugged into a crossover cable to your own computer). Computer A sends a small data packet (1534 bytes or something like that if I recall correctly), Computer B sends an acknowledge packet, Computer A then sends the next data packet, which again is acknowledged by B. Continue et al.

The problem here is that Gigabit ethernet doesn't reduce latency, it only increases the transmission rate. Yeah, you can transmit something (theroetically) 10x faster, but the latency of sending that acknowledge packet and then sending out the next data packet still exists.

A 30ms ping on E10BT is the same 30ms ping on E1000BT. There's your latency, and faster ethernet doesn't always solve that. It's more a reference of how many hops it has to go through and how busy the source and destination machines are.

The net result is that gigabit ethernet, even in a perfect environment, will never saturate the 32bit 33mhz PCI bus by itself. It will never saturate your ATA channels. It will never saturate your disk throughput even on a single hard disk (as long as you have a harddisk manufactured in the last five years)

There are uses for gigabit ethernet, home is most certainly not one of them.

 

[su root]

The net result is that gigabit ethernet, even in a perfect environment, will never saturate the 32bit 33mhz PCI bus by itself. It will never saturate your ATA channels. It will never saturate your disk throughput even on a single hard disk (as long as you have a harddisk manufactured in the last five years)

In the home, a harddrive can be completely saturated by a 100Mbit network transfer. I have disks running in servers that can stay completely busy while transferring stuff over the network. I have a 30Gig drive in my P2 300 linux box, which, if I'm transferring large stuff over to it for backup, makes any other operation on the harddrive very slow. "Completely Saturate" is a difficult goal, because of kernel priorities but I believe it can be achieved through a regular 100Mbit transfer to a machine less than 5 years old.

For a home environment, there are very few protocols that you can use that have little overhead. Microsoft removed NetBEUI from 2k and XP, which was the defacto low-overhead protocol. Everything's done using TCP/IP nowadays anyway. Until FastTCP comes out, we're stuck with it, and there's no use in running a mixed protocol network for the tiny bit of improvement you'd get.

Outside of the home, in a perfect environment, it's easy to saturate a PCI bus. Add a SCSI card, and 15 drives in a single raid volume of your choice. A PCI bus of 132MB/s can't compete with a 160MB SCSI 3 bus... if all of the harddrives benched at half of their regular speed, 10MB/s, that would be a total of 150MB/s, much more than the bus can handle.

With a nice RAID setup, a gigabit connection would work great. The problem with gigabit is that it's faster than single harddrives, so therefore it's not great for home use, but still provides an improvement.

 

[Albuquerque]

In the home, a harddrive can be completely saturated by a 100Mbit network transfer. I have disks running in servers that can stay completely busy while transferring stuff over the network. I have a 30Gig drive in my P2 300 linux box, which, if I'm transferring large stuff over to it for backup, makes any other operation on the harddrive very slow. "Completely Saturate" is a difficult goal, because of kernel priorities but I believe it can be achieved through a regular 100Mbit transfer to a machine less than 5 years old.

100 megabit, at exactly 100% full throughput (ignoring TCP overhead, ignoring acknowledge packets, figuring ONLY on true 100mbit stream to your machine) will be 11.9mb/sec. That's probably enough to saturate a disk, but that's in an absolute perfect situation that will never exist. After TCP overhead, you're gonna net about 70% of that figure. Basically all 7200RPM disks and most 5400 RPM disks can sustain 7mb/sec without issue.

Now, what you MAY be referring to is seek time. Multiple machines requesting multiple small files that are scattered all over the disk is going to result in a lot of seek time. Combine that with a machine that's set up as a "server" caching role that doesn't have a lot of memory, and you now get seek time as well as paging time.

That's not your network saturating the bandwidth of your drive, that's all the requests saturating your HD's physical head movement limitations.

Unless you're running a really nice RAID at home with fast-seeking drives while also serving files to multiple machines making multiple different requests, gigabit really isn't going to do anything at home.

Honestly, if you DID have that situation, the best thing would be to find a single gigabit nic for your "server", and a 10/100/1000E switch to plug everything into. There's no need for all your boxes to have gig nics in them, just the one that's going to handle the major traffic. Put a gig nic in your high-capacity server, plug it into a good 10/100/1000 switch, and leave everything else 100mbit. You'll never saturate the link to the server, and you likely will never saturate the individual links to your other machines.

Problem solved

 

[su root]

Actually I was referring to the average sequential read and average sequential write speeds of a 7200rpm ide harddrive on an ATA/66 bus.

The average is about 20MBytes/s, from what I've seen. Buffered squential reads are in the 45MBytes/second range, or higher, cached ones are super quick, and random reads/writes are very low (like 10MBytes/s).

On a 100Mbit lan, your top theoretical speed is 12.5MBytes/s, however, in an average network, with overheads, attenuation, and all that jazz, you see less than 80% of that, at 8-10MBytes/s.

My idea here was not to completely saturate the drive on 100Mbit (that's easy to do), but to show that a regular drive is underused by 100Mbit, and that it can be better used by gigabit.

Using the average number of 45MBytes/s buffered sequential read, that's 360Mbits... that's 3.6 times faster than 100Mbits on average conditions, with a lot of room to grow for overheads. You don't need a RAID setup to take advantage of a gigabit network, only if you want to get blown away by the speeds.

 

[Perre]

Gigabit isn't THAT expensive, is it?

Me and a couple of friends bought a gigaswitch (all of us have giga nics) and as long as you're just playing it makes no difference, but once you start to copy large files..damn...

I get atleast 30MB/sek instead of 10MB/sek (over ftp)

I tought that might contribute with some simple facts to this more comlicated discussion