2700 switches do not support dynamic link aggregation (LACP).  They support static link aggregation.

You can use the 2700 switches, you just have to configure linux to use static link aggregation.

Dell switches that support LACP (dynamic link aggregation) are the 3000, 5000, and 6000 series switches.

Here's a link:

http://www.cyberciti.biz/howto/question/static/linux-ethernet-bonding-driver-howto.php

Look at Bonding Driver Options.  Set the 'mode' to 'balance-xor'

802.3ad or 4

                IEEE 802.3ad Dynamic link aggregation.  Creates
                aggregation groups that share the same speed and
                duplex settings.  Utilizes all slaves in the active
                aggregator according to the 802.3ad specification.

                Slave selection for outgoing traffic is done according
                to the transmit hash policy, which may be changed from
                the default simple XOR policy via the xmit_hash_policy
                option, documented below.  Note that not all transmit
                policies may be 802.3ad compliant, particularly in
                regards to the packet mis-ordering requirements of
                section 43.2.4 of the 802.3ad standard.  Differing
                peer implementations will have varying tolerances for
                noncompliance.

                Prerequisites:

                1. Ethtool support in the base drivers for retrieving
                the speed and duplex of each slave.

                2. A switch that supports IEEE 802.3ad Dynamic link
                aggregation.

                Most switches will require some type of configuration
                to enable 802.3ad mode.

You have to create the group on the LAG membership page.

I have ordered the 2724!

Well, i have ordered two of them :)

I have understand that I can't use the "Mode 4" and you suggested me to use "mode 2".

Are there other "modes" I can use with this switch?

What's the most performant mode I can use with that switch?

Because of my bad english, I didn't uderstand exactly what "mode 2" does, I have only understand that provdes load balancing and fault tolerance. How does it work? I mean, there's a server with 4 port bonded in mode 2 with the switch.

If 2 computer attached to the switch ask 2 different files from the server, what happens? One file is sent through one interface of the server and the other file via the other interface of the server?   

Thanks again :) 

thanks for replying!

What about the "reverse street", i mean some clients that puts things on the server? Does it work on the same way of the "server to client street? 

So what about a situation of a server with 4 port bonded in mode 2 to the switch, and 15 computer attached to the switch asking files from the server? 

Do you think it would be a good configuration?

So, the only mode I can use is mode 2?