Linux and either Dual Port NICS or 2 NICS

[bookem dano]

Is there a dual port nic or 2 nics + software that allows a server to have 1 IP and merge the bandwidth? We have a cisco switch that enables 2 ports to share one IP and become virtually one port which will double the bandwidth to the server.

Thanks!

 

[Russ]

I think the Intel Pro/100 Dual Server NIC will do this, although I don't know if it will do it in Linux.

Russ, NCNE

 

[bookem dano]

Yeah, I came across that, and I think it does support Linux, but I couldn't find if it will do what I wanted it to do.

 

[spidey07]

i'll second russ. but don't know about driver for linux. Really the only nics i've seen that do this very well are intel and sun.

but even then you get into how the switch and card actually load balance...Based on MAC or IP. Both options work well depending on the topology.

In a small lan where most of the traffic is local then balance on MAC. On campus or medium sized networks+ balance on IP since almost all traffic to or from the server is going to a router. The algorithym is controlled by the switch for trasmission out of the port, and the receive portion of the port (TX from NIC) is controlled by the driver.

btw...i've never heard of a router doing layer 2 load balancing, do you mean a switch?

 

[bookem dano]

Yeah..it is a switch...brainfarts suck.

 

[spidey07]

 

[fivepesos]

to load balance under linux with a single ip under linux, id recommend a different approach. all incoming data arrives on eth0, then the linux box sends data out on eth0 and eth1 (or whatever eth# they are).

this may be useful if u SEND more data then u recieve. this may work for a webserver where requests are rather small compared to data, but most likely not for database where they are fairly similarly sized data.

under linux, this is called equal cost multipath routing. there are very few documentation of this feature. i have gotten this too work with dual cable modems, under 2.2.16 and ipchains (although other kernels support it, ive never tried). u need to do the following:

1)compile kernel to support equal cost multipath routing (under networking sections, advanced router i believe).
2)load your new kernel, gotta restart your linux box : (
3)add two default routes, route add default gw XXX.XXX.XXX.XXX, for each device.
4)this should be all

under load, you should now see the devices blinking alternately as they route data. for the client connections, they would appear to be coming from different IP addresses. i used this for IP Masq to my internal lan and it worked great (18 person lan party on dual cables). but the inside client machines didnt care what interface they went through (they were oblivious to my outside ip address anyway).

this may work if your client machines don't care where the data comes from (but must do). if the data is returning from your box to the clients and passess through a firewall/nat/whatever that flags connections by IP addresses then this wont work. i dont even think most client connections will accept incoming data from sources it hasnt requested.

as a wrote this i kindve awnsered to myself why this setup wont work. its still interesting in situations where client machines are oblivious to external IPs (ipmasq).

 

[Damaged]

Funny, I was just looking into whether or not the Intel Pro 100+ Server NICs could be teamed under Linux, this was kind of the original question. As it turns out it can be done. Here's a link to the drivers:

Intel Forums

That's a reply to someone who asked the question and it has a couple of links there.