Allied Telesis AT-S82 - Manual (Page 32)

Chapter 4: Trunking
32
Trunking Overview
A port trunk is an economical way for you to increase the bandwidth
between the Ethernet switch and another networking device, such as a
network server, router, workstation, or another Ethernet switch. A port
trunk is a group of ports that have been grouped together to function as
one logical path. A port trunk, therefore, increases the bandwidth between
the switch and the other network device and is useful in situations where a
single physical link between the devices is insufficient to handle the traffic
load. The AT-S82 management software provides for four trunks with a
maximum of two ports each.
Because network vendors employ different techniques to implement
trunking, a trunk on one device might not be compatible with the same
feature on a device from another manufacturer. Therefore, trunks are
typically made only between devices from the same vendor.
If a port in a static trunk loses its link, the trunk’s total bandwidth is
reduced until the lost link is reconfigured.
Trunking
Guidelines
The following are guidelines for setting up trunking:
ˆ To ensure compatibility, set up trunks only between AT-GS950/8
devices.
ˆ The trunk always contains two ports, one of which is designated the
master port.
ˆ The AT-S82 management software is preconfigured for you to select
trunks 1, 2, 3, or 4, with ports preassigned to each trunk. Trunk 1 has
ports 1 and 2, trunk 2 has ports 3 and 4, and so forth. You cannot alter
either setting.
ˆ Before you create a trunk, examine the speed, duplex mode, and flow
control settings of all the ports that will be in the trunk. Verify that the
port settings are identical.
ˆ After you create a trunk, do not change the speed, duplex mode, or
flow control setting of any port in the trunk without making the same
changes to the other ports.
ˆ The ports of the trunk must be members of the same VLAN.
ˆ The switch selects the lowest numbered port in the trunk to handle
broadcast packets and packets of unknown destination. For example,
in trunk 2 containing ports 3 and 4, port 3 is used for broadcast
packets.
Trunking
Algorithm
One of the steps in creating a trunk is the selection of a load distribution
method, also known as the trunking (or load distribution) algorithm. This
algorithm determines how the switch distributes the traffic load across the
ports of the trunk. The AT-S82 management software provides three load