Gigabit Ethernet switch under Megabit router

Question

Suppose I am very poor, which I am, I can only afford a 10/100 router and a gigabit switch.

If I am to connect everything under my router which runs at 10/100M, everything will of course runs at 100M.

Now my problem is, if I am to connect my stuff like this:

router w/ Internet connection

- Gigabit Switch

    - Computer 0

    - Computer 1

And both of those computers have NIC capable of doing gigabit Ethernet.

My problem is,

a) Will they get DHCP IP from my router?

b) Will they communicate at gigabit speed?

(I am quite poor as it comes to knowledge about Internet switch and what they do, if anyone is to elaborate that further. It's much appreciated.)

Answer 1

Link speed is selected per port.

This means that your gigabyte speed capable switch will communicate at Gbit speeds with "computer 0" and with "computer 1", and will communicate at 100 Mbit with the router.

It will accept data from any port, store it internally, and retransmit it on the other port.

This means that if a computer send data at Gbit speeds that the switch will happily accept the data, store it, and transmit it to the router at 100mbit speed. So, yes, communication is not a problem and it will work. You will get a DHCP lease from the router and your computers will be able to reach the internet.

Not asked, but note that both computers can communicate with each other at sustained Gbit speeds. Unless you need this speed or unless your router has insufficient ports you might as well connect both computers to the ports on the router, saving a device, desk clutter, some power and the price of a Gbit switch.

Answer 2

I use exactly the same setup. Works fine.

a) A switch does not alter the network traffic, it just mixes it up and buffers it sometimes. Therefore both computers will talk to the router for DHCP.

b) The computers will communicate using 1 GbE between each other but use 100 MbE talking to the router.