Allied Telesis AT-S79, User Manual, Page: 58 / 210

Chapter 5: Port Trunking
58 Section I: Using the Menus Interface
Port Trunking Overview
Port trunking is an economical way for you to increase the bandwidth
between two Ethernet switches. A port trunk is 2 to 8 ports that have been
grouped together to function as one logical path. A port trunk increases
the bandwidth between switches and is useful in situations where a single
physical data link between switches is insufficient to handle the traffic
load.
A port trunk always sends packets from a particular source to a particular
destination over the same link within the trunk. A single link is designated
for flooding broadcasts and packets of unknown destination.
Port Trunking
Guidelines
Observe the following guidelines when creating a port trunk:
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A port trunk can consist of up to 8 ports.
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The switch can support up to 7 trunks.
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A port can belong to only one trunk at a time.
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The ports of a trunk must be of the same medium type. For example,
they can be all twisted pair ports or all fiber optic ports.
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The speed, duplex mode, and flow control settings must be the same
on all the ports in a trunk.
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The ports of a trunk must be members of the same VLAN. A port trunk
cannot consist of ports from different VLANs.
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The ports of a trunk do not have to be consecutive.
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When you cable a trunk, the order of the connection should be
maintained on both nodes. The lowest numbered port in a trunk on the
switch should be connected to the lowest numbered port of the trunk
on the other device, the next lowest numbered port on the switch
should 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-GS950 switches. On the first AT-GS950 switch you select ports 1
through 4 for a trunk. On the second AT-GS950 switch you select ports
6 through 9. To maintain the order of the port connections, connect
port 1 on the first AT-GS950 switch to port 6 on the second AT-GS950
switch, port 2 to port 7, and so on.
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To avoid compatibility problems, Allied Telesyn recommends creating a
port trunk only between AT-GS950 Series switches. A port trunk
between an AT-GS950 Series switch and a device from another
manufacturer might result in undesirable trunk behavior.