I've got this weird issue with Link-Agg right now and I'm seriously confounded by it. I have Link-Agg setup for two HP StoreOnce (D2D 2504i) devices. One device sits at site A and another at site B.
Little background:
Site A has 4 HP A5800-48Gs. The 48Gs are configured in a single IRF domain with forward and backward redundancy (read daisy chained). Site B has 2 HP A5800-24Gs. the 24Gs are configured in a single IRF domain with forward redundancy (read a single link between the switches). The StoreOnce device has a port on alternating switches.
In site a the LAG is working optimally. Everything is up and going and testing so far has yeilded good behaviors. My problem is in site B. The StoreOnce device only works when one member of the LAG is administratively down. If you bring up both ports of the LAG, I am unable to ping it from any other host on the network. Interesting part: The switch can ping the StoreOnce device when both of the LAG links are up.
Here is an example of the config (both sites are configured identically with exception to the design of the cores):
interface Bridge-Aggregation1
description Uplink for HP D2D Device
port access vlan 7
interface GigabitEthernet1/0/11
port link-mode bridge
description HPD2D Port 1
port access vlan 7
port link-aggregation group 1
interface GigabitEthernet2/0/11
port link-mode bridge
description HPD2D Port 2
port access vlan 7
port link-aggregation group 1