The Guide had this to say about traffic distribution:
Table 12-3. General Operating Rules for Port Trunks
Traffic Distribution: All of the switch trunk protocols use the SA/DA (Source Address/Destination Address) method of distributing traffic across the trunked links. See “Outbound Traffic Distribution Across Trunked Links” on page 12-26.
Outbound Traffic Distribution Across Trunked Links
All three trunk group options (LACP, Trunk, and FEC) use source-destination address pairs (SA/DA) for distributing outbound traffic over trunked links. SA/DA (source address/destination address) causes the switch to distribute outbound traffic to the links within the trunk group on the basis of source/destination address pairs. That is, the switch sends traffic from the same source address to the same destination address through the same trunked link, and sends traffic from the same source address to a different destination address through a different link, depending on the rotation of path assignments among the links in the trunk. Likewise, the switch distributes traffic for the same destination address but from different source addresses through different links. Because the amount of traffic coming from or going to various nodes in a network can vary widely, it is possible for one link in a trunk group to be fully utilized while others in the same trunk have unused bandwidth capacity even though the address assignments are evenly distributed across the links in a trunk. In actual networking environments, this is rarely a problem.
However, regardless of which mode I use to configure the bonding interface...
balance-rr (mode=0)
active-backup (mode=1)
balance-xor (mode=2)
broadcast (mode=3)
802.3ad (mode=4)
balance-tlb (mode=5)
balance-alb (mode=6)
...the combined throughput never exceeds 1 Gbps. In fact, in balance-rr mode (mode=0) throughput averages ~600 Mbps. And in broadcast mode (mode=3) throughput averages ~160 Mbps!Is there some host configuration that needs tweeking here? e.g., xmit_hash_policy
REFERENCE
http://www.linuxfoundation.org/collaborate/workgroups/networking/bonding