Mixing 100mb and 1Gb ethernet

Nothing to do with Linodes, or even particularly Linux.

If I plug a 1Gb/s fileserving system into a cheapo (non-managed, etc.) 1Gb/s switch, and also a few 100Mb/s client systems, will each client be able to pull 100Mb/s from the fileserver, or will the fact that the clients are 100Mb/s cause the switch to downgrade the 1Gb/s connection to 100Mb/s? (Yeah, I know I'm ignoring things like ethernet/ip/tcpp overhead, and whether or not the NAS can actually fill a !Gb/s pipe, and so-on. I'm just concerned with whether I'll get any benefit at all from the 1Gb interface.)

If, as I suspect, the answer is "it depends on the switch", what magic phrase/number should I look for on the switch?

4 Replies


If your switch is 1Gbit, chances are very good that it also support 100Mbit and 10Mbit connections.

If your fileserver has a Gbit NIC, you should theoretically be able to service multiple clients at 100Mbit. The switch will only "downgrade" the clients connected at 100Mbit, not the whole switch.

Having said that - your fileserver must be fairly powerful to serve up a sustained feed of 1Gbit/sec to multiple clients, especially if your clients are accessing different sets of data which will cause your disks to seek more than just read.

Also, most NAS systems out there simply can't serve up more than about 120Mbit/sec. See ~~[http://www.smallnetbuilder.com/content/view/26378/75/1/10/" target="_blank">](http://www.smallnetbuilder.com/content/ … 8/75/1/10/">http://www.smallnetbuilder.com/content/view/26378/75/1/10/]( for more info on several NAS boxes' throughput.


Yes, the switch supports 10/100/1000 on each port. So "The switch will only "downgrade" the clients connected at 100Mbit, not the whole switch." is exactly what I hoped to hear. Thanks.

And no, I don't expect that any home NAS/Server system that I can afford to buy or build will fill a 1Gb pipe. But I was hoping to avoid the need/desire to upgrade the existing clients to 1Gb, and it sounds like I don't need to.

Smallnetbuilder is very informative site. The guy seems to have a good handle on reality and what's actually useful, unlike some of the fanboy-type sites.

One other thing to keep in mind - gigabit will indeed provide a noticeable improvement in speed, but unless you can use "jumbo" ethernet frames (very large MTU values) you'll see maybe a doubling of speed at best. I don't think jumbo frames can be used though, unless your network is 100% gigabit and all switches, routers, and clients support it.

Ah, thanks. I was aware of the concept and importance of jumbo frames, but didn't realized they were unique to the 1Gb standard. I guess I can live with that until I transition to all-1Gb clients.


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