Solaris

bonding and trunking are dependent on your type of interface they are using.
trunking would be like a qfe and link-aggr would be something like nxge.

they are pretty much the same thing.

anyway, lets see the output of ifconfig -a, dladm show-aggr and netstat -rn . finally, how are you determining that rsync or some other file transfer is only using a single interface? i have to ask if the second link in the bonded pair is up.

obelix:/# ifconfig -a
lo0: flags=2001000849<UP,LOOPBACK,RUNNING,MULTICAST,IPv4,VIRTUAL> mtu 8232 index 1
inet 127.0.0.1 netmask ff000000
aggr1: flags=1000843<UP,BROADCAST,RUNNING,MULTICAST,IPv4> mtu 1500 index 2
inet 192.168.17.8 netmask ffff0000 broadcast 192.168.255.255
ether 0:30:48:8a:c6:ee
obelix:/# dladm show-aggr
Schlüssel: 1 (0x0001) Richtlinie: L4 Adresse: 0:30:48:8a:c6:ee (Auto)
Gerät Adresse Geschwindigkeit Duplex Link Status
e1000g0 0:30:48:8a:c6:ee 1000 Mbps full up attached
e1000g1 0:30:48:8a:c6:ef 1000 Mbps full up attached
obelix:/# netstat -rn

Routing Table: IPv4
Destination Gateway Flags Ref Use Interface
-------------------- -------------------- ----- ----- ---------- ---------
default 192.168.17.1 UG 1 0
192.168.0.0 192.168.17.8 U 1 11 aggr1
224.0.0.0 192.168.17.8 U 1 0 aggr1
127.0.0.1 127.0.0.1 UH 4 76 lo0
obelix:/#


Yes, they are up. I ran an rsync for several hours and checked the statistics for both interfaces:

obelix:/# !375
dladm show-dev --statistics
ipackets rbytes ierrors opackets obytes oerrors
e1000g0 783204 55453484 0 20321 4288909 0
e1000g1 68599 8120481 0 7719021 10998514776 0

See the difference?