Pro-tip time. Brocade MLXe's by default won't pass an non-routed L2 VLAN across ports even if the VLAN configuration is correct on the box. This is because MLXe's operate in "pure router mode" and won't switch packets between ports. Routing packets is fine, switching is not. The key to make them switch packets is the command "no route-only". This will enable L2 VLAN switching of packets. I know I am not the only person to hit this "feature" when working on an MLXe router.
Now I know. And knowing is half the battle.