Networks multiple NICs and load balancing?

Would it be possible to install multiple NICs in the same computer, connect them to the same Ethernet switch, and increase the bandwidth?
The switch is a Cisco Catalyst 2900 XL.

 

I would think so, but you would have to be getting that data from a source capable of providing it.

Are you pulling stuff from 2 servers or something and will they actually saturate the 100mbps on each line? But the real question is will windows see it as 1 network or as 2 identical but seperate networks?

 

2 networks

you'd need some way to bond the connections, and I have no idea how to do that

 

no i don't think that would work. Becuase untimatly, each connection to a switch isn't 100mbps, it's 100 mbps divided among all the computers connected to that switch and only a single computer can be sending data through that switch at a given time. If you had 2 100mbps cards each in 2 computers and used a crossover cable for each connection, then it might work, provided you were sending 2 differnt files (1 over each connection). The only real use for dual nic cards is in a server that is acting as a gateway/firewall or just bridgeing 2 subnets. Ultimatly having 2 network cards connected to the same network is just asking for problems, windows will probably go haywire and if you bridge the connections and don't do it perfect, your switch may not work. Also it would probably register each connection as a seperate computer and say that theres another computer on the network with the same computer name.

Sorry to rain on your parade

^^ everything above is to the best of my knowlege, im only about 70% sure on this one.

 

i have done this using windows, and here is what i find.

1. the computer that has the two nic's has two IP's (given from my DHCP router)
2. Windows did NOT go "haywire"
3. when accessing the network it does NOT show up as two Computers
4. I cant get it to work (within windows) as one nic to Transfer and the other to receive. but sometime then moving files to the pc, i get a faster speed than Normal, the only thing i can see that causes this is some times one of the nic is only receive my file and the other is being use for the P2P program (that runs on this server).

 

there are several ways to do it depending on your hardware and your drivers for the network cards.

An early way I came across with compaq kit was an adaptor teaming option which esentially disabled the receive channel on one network card whilst enabling the transmit on both. The effect was that whilst you had a 100Mb receive channel you could deliver data into the network at 200Mb which was good for a filre server - not so good for a print server.

Other options have involved things like DNS round robni to load balance which isn't overly reliable.

In your case you can use a cisco technology called EtherChannel. effectively you will create a bonded set of ports on the 2900 [up to 8 using the default method] and then run compatible drivers on your PC and you get a logical interface which equates to the ethernet bundle of 2-8 connections and acts like a single interface.

To configure this on your 2900 you would need to issue the command

port group 1

on each interface you wish to participate in the channel.

HTH

J

 

wonder if you can to this within windows, will try it this eventing when im off work.

 

This is wrong.

The whole point of a switch is to provide a dedicated port to port path across the switch that can run at full speed - subject to the limitations of the switching fabric and these only tend to come into play on the very high density switches as most small switches provide a fabric capable of non-blocking operation. A hub, on the other hand, does provide shared bandwidth.

So on an average switch, at any given point in time you can have n/2 connections all running at full speed where n is the number of ports on the switch. Where bottlenecks do begin to exist, however, is where you have multiple devices all talking to a single server in which case obviously the path into the server becomes the limiting factor. It is for this kind of reason that technologies like Port Aggregation, Etherchannel and the like exist, so you can increase the bandwidth into the server and remove/alleiviate the bottleneck. Obviously these days you could also use things like Gigabit to get around the problem but only if you have gigabit capable switches and devices.

J

 

IIRC it was just a function of the compaq network drivers that came with the hardware - the platform was NT4 so I'd imagine you can still do it with the right drivers/nics under 2K/XP

J

 

i know intell offer the same thing with some of there cards, (the card i got in the server are 3com) but as i said will try it tonight

 

In a simple answer: No..


But you can, however it requires a NIC that supports load balancing also known as NIC teaming..

Ever see a 4 port nic for a server (64 bit slot)? Those generally come with the software to load balance.

-scoob8000

 

yep he's right

 

sorry i should have worded my post quite differently then i did. I was thinking along the lines of it would be the 100mbps spread across the switch from the uplink port (unless its gigabit uplink). I was presumeing that it was a larger network and any traffic would be going though the uplink port. Unless you had 2 networkcards in each of the computers or had 2 seperate computers that you were exchangeing data with. But for all the trouble its worth, id just reccomend going gigabit.

 

Theres some software called NIC Express which lets you bond network cards in 2000 and XP. I've used it to bond 3 NICs for 300meg send and receive.

 

i demand a linky

 

NicExpress at FalconStor. .......Only $495.00 US

 

Jake pretty much nailed it (unsurprisingly). You need a switch that supports some method of channel bonding, port aggregation, or whatever else the switch manufacturer wants to call it. Cisco call theirs etherchannel. Then you need network cards whose drivers support NIC teaming. Again, there's several names depending on what vendor you purchase them from. Most of these NICs are server-class (read: expensive).

The NIC driver creates a single virtual NIC with a virtual MAC address, which is used by all of the NICs in the team. The switch needs to be told that the ports are teamed, and away you go.

These days, it's often more cost effective to buy a gigabit NIC and a switch with a couple of gig ports than to buy 4 100Mbps NICs which support teaming and a switch that also supports it. Of course, if you want to team multiple gigabit NICs, then you're talking serious money for the hardware, and you have to start worrying about PCI bus bottlenecks and such.

Cheers
Buzzy

 

buzzy hit the nail on the head there, as to how one would do it if the switch supports it.

But there are other ways of doing it.

if say you wanted one NIC to use purely for the internet, the other LAN, so you could game, whilst people where pulling files off you (if u have a sweet as dual machine, with a nice scsi hdd or 2) then the simplest way would be to set up the ROUTES. this is done in NT by cmd -> ROUTE /?

simps.

This means you can set some IPs over one route, and others over the other route, each route has an interface.

 

You could do that as a cheap'n'cheerful solution. If you connected to the machine by name it'd involve having a DNS server and doing round robin or having multiple hostnames, otherwise you'd have to get people to connect by IP, and you'd probably find that the people leeching from the box would use up all the bandwidth on one NIC while the other was underutilised.

Also, you wouldn't have to define routes if you had both of the addresses on the same subnet