Which 8-port gigabit switch to buy?

[gherald]

Right now it's a tossup between these two:

3Com OfficeConnect Gigabit Switch 8
Netgear Copper Gigabit Switch (GS108)

Here's the specs I'm trying to differentiate:

3Com: 1 MB buffer memory; 4K MAC addresses
Netgear: Memory: 32KB Queue buffer per Port; 8K MAC addresses

For the Netgear I figure the 32KB buffer per port means 32*8 = 256kb buffer memory? So the 3Com looks like a better deal... but how do they compare otherwise?

It will be interfacing with a large 100mbps ResNet-style network (~5k college students PCs), so would the 8K MAC actually be useful? How would the 4K fare?

 

[cmetz]

The MAC address table size represents how many active systems the switch can filter traffic for - if you have more than that many active stations, it's going to thrash its filter table and/or blow open, and so it's just bad. But if you seriously have 4,000 active stations on the same Ethernet subnet, you deserve to have problems. Nearly all modern switches have enough MAC table entries for real networks, so this is rarely something to be concerned about.

The packet buffer is needed to deal with transient load, for example, if two gig ports send a short blast of data destined for the same gig port, some data has queued in the buffer waiting to get sent out (can't send 2Gb/s out a 1Gb/s port, so some data has to wait). The size of the buffer tells you how much transient load can be queued before frames just get dropped. More is better. You need to have at least (bandwidth * link delay) bits of buffer available for each port for any IP link to ensure there's no packet loss under normal TCP conditions. On a LAN, the link delay is small, so your buffer requirement is small.

So in practice, I don't think there's a compelling difference between the two. If I were to pick, I'd take the 3Com, because buffer is more likely to matter than MAC table.

 

[gherald]

Yeah thats what I figured so I went ahead an ordered the 3Com. Looks to me like the best option for the money... or does someone know of a better deal?

I decided to shy away from the ~$117 Trendware model, since it only had a 128k buffer plus I wanted something from a major brand.

 

[cmetz]

Folks seem to like the SMC. It does jumbo frames, which is a feature that is important for gigabit in my opinion.