Gigabit vs Aggregated NICs

[bry74]

I'm looking at upgrading a small business network (~40 clients). Right now we are on a few 24-port hubs. We are going to get rid of them, and go with 3com switches.

We also want to improve the backbone to the server, our inital thought was gigabit over copper but I have a few concerns. Based on my basic knowledge of Ethernet technology, only one packet can be transmited at a single time by a NIC. Even though we would have gigabit to the server, the packet isn't going to move much faster than the client can support. (I guess some buffering would occur at the switch, but really how much?). But if this was really the case, then what would the point of gigabit technology be except if you have gigabit clients or more bigger backbone stuff?

Based on this, wouldn't aggregated NICs be a better solution? I've been looking at the 3Com SLB (Smart Load Balancing) technology. I was thinking 2 subnets with aggregated NICs (maybe 2 each) to each subnet.

The server should be able to handle a lot more than it is right now. It is RAID 5 with 10k RPM drives and dual PIIIs.

Is my logic flawed here?

Thanks for any suggestions you may have
Bryan

 

[Xanathar]

Keep It Simple Silly... 1 Nic will handle it just as well as 4. You will also not need to worry about subnetting, or a cumbersome design.

 

[Agamar]

Yes, if only 1 client is using the server, then 1 gig is overkill. But if 24 clients (@100BT) are using the server, and they are attached to a switch, at full duplex they could theoretically be using 200Mbs apiece. Now if your server was running 1 100Mbs nic, you would have a problem. Get the Gig over Cu, you will save yourself some problems later. Aggregating was the way things used to be done if you wanted higher bandwidth. Gig over Cu is the cheapest way to go.

 

[bry74]

I'm still a little confused about this Agamar.

If i have 5 clients @ 100BaseT trying to communicate with the server at the same time, only one packet is sent to/from the server at any particular moment. So what advantage is gained by going to Gigabit?

Or is the architecture of Gigabit Ethernet such that it allows multiple simultaneous packets to be transmitted?

Does the switch perform some buffering such that the server can quickly move the packets onto the switch and get onto the next client request?

Bryan

 

[SocrPlyr]

it can send more data at one time there by finishing it's work w/ each client more quickly

 

[wlee]

Get the HP ProCurve 4000 switch. It has 40 10/100 ports as standard and 5 open expansion bays that you can put Gigabit ports or 10/100 ( 5 ports per ) You do need the second power supply if you add cards though. This switch has very low latency. Seems to work much better than the 3Com stuff. Gigabit should work much better than channel bonding, and won't have any of the probs associated with that trickery. One exception is *IF* your server is WinNT4 *AND* you use one of the Alercritich 4Port Ethernet cards. This config has better performance than a single Gigabit card, but is *VERY* proprietary. Overall, cost and maintenance issues should be less using a single Intel Gigabit card. One warning though, Gig over copper is VERY finicky about wiring. If your server is not in the same rack or room as your switch, Then you MUST have PERFECT Cat5E wiring *AND* NOT have a lot of RF noise in the environment. E.G., air conditioner, electric service panel in close proximity to wiring. In that case you would require Optical Cable.

 

[L3Guy]

A couple of quick comments.

NIC throughput will be limited on a 32 bit 33 MHZ pci bus. I think that the absolute max
would be 250 Mbps, assuming everything else is blazing fast, especially the HD. If you have need for more speed, definitely a 64 bit 66Mhz PCI bus in a server class machine is in order.

Link aggregation ( the generic term for using multiple Ethernets as one pipe) usually allows one conversation to use only one of the Ethernets. In other words, there is a 100 Mbps limit
on any Link aggregated transfer, even if both machines had multiple nics. Probably not a big deal in a home setup.

I have access to a smartbits and had the opportunity to test the 3Com switches. I have tested the Switch 1000, 1100, 3300, and 3900. Their latency and throughput numbers were very competitive with the other switches I have tested. In a small office setup, it would be unlikely
that Latency would be a noticeable factor between switch vendors.

HTH

Doug

 

[Ender78]

Bry,

What type of traffic are you running. How heavy is the utilization of the server at this time. Chances are that the upgrade to a switched 100 Mbps Full Duplex topology will solve all your speed problems.