uplinking icx8200 to fortinet

[Nate]

so, i have existing ICX8200’s in this infrastructure and older ICX6450’s.  we’re replacing the 6450’s with 124F-FPOE switches, but i’m having trouble getting the 124’s to talk to the 8200’s.  the 124’s are running 8.0.0(47).  the 124’s will uplink to the 6450’s with no trouble, but will not pass traffic to/from the 8200’s.  the link and activity lights come on, and in the gui the link and speed/duplex are correct, but both switches claim they are sending but not receiving.  neither have errors in the log.  

so,

fn124 → icx6450 → icx8200 works fine

fn124 → icx8200 link but no stp/lldp/traffic

no cdp/fdp/lldp neighbors listed on that port when the 8200 is plugged into the fortinet.  on either switch.  when the 6450 is plugged in the middle everybody sees the directly connected neighbors.  i’ve tried this with 2 separate icx8200’s and 2 separate fn124f-fpoe’s.  i’ve pulled one set and experienced the same behavior on my bench using fiber patch cables.  the ports on both ends are set to native vlan 1 and tagged on the rest.

i’m out of ideas at this point.