Networks Routers and switches

[Zener Diode]

Hi. I'll start by saying I have a lot to learn about networking

So I want to have the capability to transfer files between two computers as quickly as possible. My modem/router is only 100Mb and it is in a different room so I'd like to avoid running two cables to it if possible. I have one Ethernet cable connected to my PC. So I was thinking, would it be possible to connect that cable to a switch, then connect the other machine to the switch and be able to receive internet from the modem/router and also transfer files between the two PC's via the switch? I have tried to make a diagram of what I mean below.



If the above configuration is possible, could I transfer at gigabit speeds between the two machines, and still get internet as normal?

Thanks

[debs3759]

That's how I have my network set up (well, not quite - I also have a hub between the switch and PCs).

Yes, you will be able to transfer between computers and use the internet at the same time. The maximum TOTAL transfer speed is the speed of the switch (so you could, for example, have 990 Mb transferring between the PCs and 10Mb off the internet). It is likely that you will get full internet speeds, with PC to PC transfers being reduced by whatever the speed of your internet is.

[Zener Diode]

Perfect, thanks

[jamesn]

dont be suprised if you dont max out the potential speed of gigabit connections. i often find that transfer speeds average out at about 90MB/s

[Zener Diode]

I hear you jamesn, I could live with 90MB/s though, it's probably ten times what I'm getting at the moment.

[GoodBytes]

I have similar setup. In my case, I disabled the router of my modem/router combo unit as, like all combo units, the router usually is total crap. And use my own router.

So modem -> router, and computers (and wireless computer/device) all connects to my router.

[Zener Diode]

Yeah, my modem/router is a crappy one provided by my ISP. Some day I plan on upgrading to a separate modem and router setup, or at least a better quality combo. Thanks for the input.

[stevenrlp]

Just so you know that when host A sends frames to host B the router will not get involved at all with the transfer as both hosts are on the same network segment.

To get the best speed you need to ensure that you are using 1gbps full duplex NICs in both hosts and that you are running at least category 5e straight through cable between the hosts and the switch. So theoretically you can run at 1000mbps transmit and receive, but realistically its a lot less.

[leslie]

The router coordinates traffic, but once set up, the switch handles the flow.

As for speeds, it depends on drivers, hardware and the method of transport.

The theoretical limit of gigabit is around 125MB (bit vs byte)or so, but very few get above 100MB in my experience (I can manage 114 on large files, but average closer to 80), if you think that is bad, some small NAS boxes transfer at a max of 40MB.

[stevenrlp]

Originally Posted by leslie

The router coordinates traffic, but once set up, the switch handles the flow.

Sorry dude that's wrong, when two devices are on the same network segment then there is no need for a layer 3 device to get involved.

1. Host A will use ARP to get the MAC for Host B,
2. Host A will transmit its segments to the port on the switch
3. the switch will then lookup its MAC table and see if the source address is in there, if not it will add it as well as the port number.
4. the switch will then look up the destination address in its MAC table, if it don't find it then it floods the frame out every port except the one it received it on, if it does find it will forward the frame out the port host b is on.

so as you see the router is not involved in this process.

[leslie]

Originally Posted by stevenrlp

Sorry dude that's wrong, when two devices are on the same network segment then there is no need for a layer 3 device to get involved.

1. Host A will use ARP to get the MAC for Host B,
2. Host A will transmit its segments to the port on the switch
3. the switch will then lookup its MAC table and see if the source address is in there, if not it will add it as well as the port number.
4. the switch will then look up the destination address in its MAC table, if it don't find it then it floods the frame out every port except the one it received it on, if it does find it will forward the frame out the port host b is on.

so as you see the router is not involved in this process.

So set up two dhcp computers to only switch and see what happens.

Yes, a switch will take over, but the router still has to deal with initial addressing, unless you are running on static IP's, which is something most home users are not doing.

[stevenrlp]

Originally Posted by leslie

So set up two dhcp computers to only switch and see what happens.

Yes, a switch will take over, but the router still has to deal with initial addressing, unless you are running on static IP's, which is something most home users are not doing.

Yes the router is responsible for DHCP and forwarding DNS requests but in this situation we are discussing they are not used. DHCP is used when the hosts are first turned on as they go through broadcasting and uni-casting their dhcpdiscover, offer, request, acknowledgement messages, once they have their information they do not need to communicate until the lease has expired.

DNS is only used when the host needs to resolve a name to an IP address, in this case you may get an initial request of Host B's IP when the computer starts up and then this information is then retained on Host A's arp table until it times-out.

[MSHunter]

CAT 6 is so cheap these days there is no reason to buy Cat 5e.
Ebuyer has good prices on long lengths of CAT cables.

[Zener Diode]

Thanks everyone
I'll probably run CAT5e from the router to the switch (because that's what I have in place already), and then run CAT6 from the switch to each PC.

[MSHunter]

That would be fine the shorter the distance the less of a difference there is between CAT 5e and 6

[leslie]

Originally Posted by stevenrlp

DNS is only used when the host needs to resolve a name to an IP address, in this case you may get an initial request of Host B's IP when the computer starts up and then this information is then retained on Host A's arp table until it times-out.

Exactly what I was getting at.