Aggregation is better than failover in the fact that it provides two or more datapaths, effectively doubling/tripling/etc... bandwidth between the server and the switch. Failover is still enabled, as if any network cable is removed the system will continue to function correctly.
To setup Aggregation:
Make sure the ports to be added to the aggregated port are unplumbed, create the aggregation thus:
dladm create-aggr -d e1000g0 -d e1000g1 1
This will create an aggregated port "aggr1" that comprises e1000g0 and e1000g1, to show the the contents of the aggregated port:
key: 1 (0x0001) policy: L4 address: 0:14:4f:1:9c:98 (auto)
device address speed duplex link state
e1000g0 0:14:4f:1:9c:98 100 Mbps full up attached
e1000g1 0:14:4f:1:9c:99 100 Mbps full up attached
Bring up and configure the new port:
ifconfig aggr1 plumb 10.0.0.10 netmask 255.255.255.0 up
and display it:
mtu 1500 index 6
inet 10.0.0.10 netmask ffffff00 broadcast 10.0.0.255
Edit the /etc/hosts and hostname.aggr1 file to make changes persistent.