Allied Telesis AT-S25 - Manual (Page 80)

Section II: Local and Telnet Mangement
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As an example of a port trunk on an AT-8324 Switch, you could use Ports
4 and 5 as one port trunk, since the ports are members of the same
group. However, you could not use Ports 7, 8, 9, and 10 because they
belong to different groups.
Creating Only One Trunk Per Group
Each port group can support one port trunk. For example, the AT-8324
Ethernet switch, which has three port groups, assuming no expansion
modules, can support three port trunks, one port trunk for each port
group. The addition of two expansion modules would enable the switch
to support two more port trunks, one for each module.
Cabling Based on Port Number
When cabling a trunk, the order of the connections must be the same on
both nodes. The lowest numbered port in a trunk must be connected to
the lowest numbered port of the trunk on the other device, the next
lowest numbered port must be connected to the next lowest numbered
port on the other device, and so on.
For example, assume that you are connecting a trunk between two
AT-8324 Switches. On the first AT-8324 Switch you had chosen Ports 12,
13, 14, 15 from port group 2 for the trunk. On the second AT-8324 Switch
you had chosen Ports 21, 22, 23, and 24 from port group 3. To maintain
the order of the port connections, you connect Port 12 on the first AT-
8324 Switch to Port 21 on the second AT-8324, Port 13 to Port 22, and so
on.
Configuring the Port Parameters of a Port Trunk
The ports of a trunk automatically assume the speed and duplex mode
of the lowest numbered port in the trunk. For example, if you create a
trunk consisting of Ports 4, 5, 6, and 7, Port 4’s configuration is
automatically propagated to Ports 5, 6, and 7. You cannot configure the
ports of a trunk individually. They can be configured only as a unit.
Configuring VLANs
All ports in a trunk must belong to the same VLAN.