What determines the speed of a LAN that consists of both 10 Mbps and 100 Mbps devices?

Answer 1

It can be any number of settings. By "Default" most network cards auto-negotiate speed. This is normally done by the card drivers by default, but the settings can be manually changed as well. You can force a 10/100 card to only talk at 100, or only at 10, etc.

For the sake of the discussion let's say you have have a 10/100mb Full Duplex switch and 5 computers connected to it. Computers #1-#4 have 10/100 cards, computer #5 has only a 10mb card.

Computer #1 talks to Computer #4, it's going to be at 100mb. That's because the switch has negotiated that both of it, and the cards are capable of talking at that speed. Same as if computer #2 talks to computer #3, or any number of combination of those 4.

Computer #1 talks to Computer #5, the switch will negotiate it at 10mb rate because that's all computer #5 can handle. It has negotiated with the switch that it is only capable of 10mbs.

I hope this helps clear things up a bit.

Answer 2

If all devices are 10 and 100 Mbps than the LAN would work at 100 Mbps.

- But if a device is working only at 10 Mbps, then the LAN would work at the slowest speed of 10 Mbps for that certain device.

Answer 3

100baseT LANs can support slower 10baseT devices but only on a switched network, not a hub, where the bandwidth is shared. On a hub the entire network will slow to near 10baseT data rates.

Answer 4

There is a proverb: the system is as strong as its weakest element. The slowest speed device.

Answer 5

If you are only talking about a LAN then it is the slowest network card on the Intranet which would be 10mbps.