Tried doing a cutover last night to new the Cisco FTD2110 HA firewall pair ether channeled to an EXOS stack. Channel came up and vlan interfaces on Extreme Stack could ping the firewall IPs. The only caveat was vlan 1 on EXOS Switch. I couldn't get it to pass traffic if I added it to the etherchannel trunk as tagged, only untagged. Unfortunately this makes it a native vlanand FTD doesn't accept native vlans.
Our goal is to make the entire network L2 and use the firewall as the gateway, so all vlan IP's and routes on extreme core will be removed (minus our mgmt vlan). AS soon as we removed the IP from the core's interface vlan 1 and changed DHCP gateways to use the firewall, traffic was dead in the water.
Another hiccup in this network is the fact they have 2 subnets assigned to vlan 1 and we want to break those apart and move them onto new vlans 101 and 102. Attempted that as well and traffic would not pass up to firewall.