All components must support gigabit ethernet to get gigabit speeds?

Given the following:

I have a D-Link DIR615 router (with DD-WRT firmware) that I use to connect to internet with PPPoE protocol. The router does not support gigabit ethernet.
I have 3 computers in the local network connected to router, all of them have gigabit ethernet cards
I want to switch to gigabit network.

In order to do that, all components must support gigabit ethernet. So I thought of buying a gigabit switch and connecting all computers with it. The switch will be connected to router (that is not gigabit). The router will only be used for internet access and won’t have computers connected directly to it.

My question is: If I'm copying files between two computers, will I get a gigabit speed? Or will the router spoils the gigabit speed? In my opinion it shouldn't spoil anything since all the traffic is on the switch. If possible, I want to know if someone has tried it.

marisxanis

Posted 2014-09-14T19:30:01.800

Reputation: 11

1If both ends can supports the same speeds then both ends will transfer at those speeds – Ramhound – 2014-09-14T19:34:19.383

Answers

No, your router will not affect internal transfers, because it won’t be participating. After buying that switch, of course.

If you want to know whether a component will slow down a network transmission, ask yourself this question: Will the transmission still work when I disconnect the suspected bottleneck? If that’s the case, it probably won’t affect the transmission anyway. Granted, there are many scenarios when this isn’t true, but these shouldn’t apply to home use.

Daniel B

Posted 2014-09-14T19:30:01.800

Reputation: 40 502

Correct enough... but the router is participating, it has 2 gigabit ports which the two computers are connected to and transferring over (it is the first hop). You should fix that. – Keltari – 2014-09-14T19:40:14.157

@Keltari No it doesn’t, because the OP wants to buy a separate Gigabit switch. – Daniel B – 2014-09-14T19:41:15.157

oh i misread his quesiton. I though he already bought the switch – Keltari – 2014-09-14T19:41:56.277

1tks for the answers, comp1 and comp2 will be connected in the gigabit Switch. does the router have anything to do with it?I mean... I'm having the DHCP server on the router... is this server used only for acquire IPs and then the packages and not directed to it? – marisxanis – 2014-09-14T20:00:20.543

@marisxanis The DHCP server is only responsible for assigning IP addresses. If we disregard the fact that leases have a lifetime, computers only contact the DHCP server once after booting. After that, its work is done. It does not participate in internal transfers or internet transfers in any way. – Daniel B – 2014-09-15T05:32:32.113

Yes, a gigabit switch will give you gigabit speeds. The only time you won't get gigabit speeds is if the data must cross a link that does not have gigabit. In the case of a gigabit switch, and both computers are plugged into it, then it does not have to cross a low-speed link to get from point A to point B. Even if you were to plug a non-gigabit computer (C) into that switch you'd still get gigabit speeds between A and B.

If, however, you plug a gigabit computer into one of the router's other ports, then you would slow down the speeds because that computer would have to cross a low-speed link (the router) to get to the high-speed computer on the switch. Note that even in this case, computers A and B would still get gigabit between each other even in this scenario, since they're on the same switch.

Wes Sayeed

Posted 2014-09-14T19:30:01.800

Reputation: 12 024

even if the router is used as a DHCP server? will not influence the flow of the packages? – marisxanis – 2014-09-14T20:01:36.750

1Nope. Because once the computer has an address it doesn't need to talk to the DHCP server again until the lease is up. – Wes Sayeed – 2014-09-14T20:04:33.600

ok, that's clear , tks – marisxanis – 2014-09-14T20:06:04.643

hmm...what if... from comp1 I'm downloading from internet... a big file, meanwhile I'm copying a big file to comp2? In this case my ethernet card would have to switch between 100 and 1000, or will choose 100? – marisxanis – 2014-09-14T21:04:38.757

The ethernet card does not "switch" speeds. The connection between the switch and the computer is always gigabit. Data on computer networks travels in packets. A low speed link takes longer to assemble and transmit those packets. The switch simply transmits those packets -- at gigabit speeds -- to the computer in question. There will just be fewer of them in a given unit of time because they are coming from a slower device. – Wes Sayeed – 2014-09-14T21:14:58.190