3Com 4510G Configuration Manual page 1143

Figure 26-6 Correspondence in non-aggregate mode for two interface modules
When two dual-port interface modules are installed, if the correspondence is not in the aggregate
mode, you can bind an IRF port to any physical IRF port
However, you must ensure that the serial number of the physical IRF port bound to IRF-port 1 is
smaller than that of the physical IRF port bound to IRF-port 2, namely, the physical IRF port bound to
IRF-port 2 should be located on the right side of the physical IRF port bound to IRF-port 1. The two
physical IRF ports bound to the IRF ports can be located either on one interface module or on different
interface modules.
If two single-port interface modules are installed, you need to bind IRF-port 1 to physical IRF port
1, and IRF-port 2 to physical IRF port 3.
If one dual-port interface module and one single-port interface module are installed, the
correspondence is the same with that when you install two dual-port interface modules. In this
situation, IRF-port 2 or IRF-port 1 can be bound to any physical port on the device, because only
one IRF port is needed on Switch B or Switch C.
Correspondence in aggregate mode
Figure 26-7 Correspondence in aggregate mode for two interface modules
Because the two physical IRF ports bound to an aggregate IRF port must be located on the same
interface module, two IRF ports (that is, two aggregate IRF ports) can only be bound to the two
physical IRF ports on each of the two interface modules respectively (as shown in
(Figure 26-6
25-6
only shows one possibility).
Figure 26-7). In