Figure 16: Invalid Trunk With Different Ethernet Line Card Models - Allied Telesis AT-SB*908 GEN2 Installation Manual

 A trunk cannot have ports from different line card models. The
trunk for the three switches in Figure 16 is invalid because it has
ports from AT-XEM2-4QS and AT-XEM2-12XT Line Cards.
Figure 16. Invalid Trunk with Different Ethernet Line Card Models

The AT-XEM2-12XS Line Card supports both 1Gbps SFP and
10Gbps SFP+ transceivers. However, trunk links require 10Gbps
SFP+ transceivers. Trunks are not supported with 1Gbps SFP
transceivers.
AT-SBx908 GEN2 Installation Guide for Virtual Chassis Stacking
Chassis 1
Chassis 2
Chassis 3
49