Trunking is a term that encompass several link aggregation technologies. These are in order from most desirable (and highest requirements) to generally least desirable (but least requirements too). trunking may also be called Bonding, EtherChannel, Port Groups, or other names. Be careful not to confuse these technologies with vLAN Trunking (802.1q/802.1ad).
802.3ad LACP is probably the "best" of the bunch. The NIC talks to the Switch, sets up the trunk and data is load balanced for both transmit and receive over all available links. It's common for managed switches (L2 or higher) to support this; most/cheaper models are limited to the one switch.
Splitting ports over multiple switches are called Inter-Switch Trunks. It's common for "stacked" or modular switches to support this. Some switches use a form of shared management and call it stacking, these generally do not support IST. Check for technologies like Cisco VSL, Brocade/Dell ISL, or SMLT/DSMLT (the industry standard extension to 802.3ad).
SLB (Swich-Assisted load balancing) is the predecessor to LACP. You manually configure the trunk at both ends. You get load balancing of transmit and receive, and redundancy; but it's all manually configured, and you have to have switches and NICs that support it. IST is generally support as in LACP above.
TLB (Transmit load balancing) is technology that does not need the switch to speak any particular protocol to coordinate the trunk. You simply plug the NICs into the switch, configure the trunking on the computer and it's good to go. The drawback: data will be load balanced for transmitting only. Receiving will be assigned to one "primary" NIC. if the Primary goes down, one of the secondaries will be promoted. This may confuse some really old switches because multiple ports are sending from the same MAC address. This protocol can span multiple switches without IST support or additional configuration.
This method is sometimes called Round Robin. There are multiple ways to schedule the sending of packets on the trunked NICs, RR being one that simple puts one packet to each port in succession. Some NICs also support more complicated schemes like Lease Queue Depth, Weight Round Robin, and Primarily with Spilover.
NFT (Network Fault Tolerance) just uses one NIC at a time. There's no load balancing at all. This is the only one that works with hubs and some really ancient switches that don't support multiple links with the same MAC Addy. The server will use the primary NIC for everything, if it goes down, it'll switch all traffic to a secondary NIC seamlessly.
Depending on what brand NIC you have, these may be named slightly differently. If you read the descriptions in the NIC's manual however, all of it's options should match up to one of these.
Best Answer
Save for a few very specific exceptions, a switch that supports LACP will have a management interface (at the very least a mostly garbage command line). You need to be able to define what ports are bonded, create static bonds instead of negotiating ones, as well as a slew of other settings.
If you're not saturating your link, LACP can provide failover capabilities so it's still worth it if you want to keep whatever's connected to it up more of the time. Keep in mind that LACP doesn't increase the performance of single node-to-node connections; an example being an iSCSI LUN from iSCSI target to a client initiator. This is the same for CIFS and NFS traffic.
So if you're looking to increase the speed of your backups on a single node, this solution won't help you. It will make your connection more fault tolerant. It WILL balance traffic from multiple clients to a server.