Allied Telesis AT-S39 - Manual (Page 84)

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❑ When cabling a trunk, the order of the connections 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-8024 switches. On the first AT-8024 switch you had
chosen ports 12, 13, 14, 15 for the trunk. On the second AT-
8024 switch you had chosen ports 21, 22, 23, and 24. To
maintain the order of the port connections, you would
connect port 12 on the first AT-8024 switch to port 21 on the
second AT-8024, port 13 to port 22, and so on.
❑ You can create a port trunk of optional GBIC modules installed in
Port 25 and Port 26 of an AT-8024GB switch.
❑ You can create a port trunk of the fiber optic ports in an
AT-8026FC switch.
❑ You can create a port trunk of the ports in two expansion modules
in an AT-8016F switch, providing that the ports are of the same
medium type and have the same operating specifications.
Load
Distribution
Methods
There are two steps to creating a port trunk. The first is to identify the
ports on the switch that are to function as the port trunk. The second is
to select a load distribution method. This second step is important
because unless you select the correct distribution method for your
configuration, the switch might not evenly distribute the load across all
the links of a trunk. Naturally, this could greatly diminish the value and
purpose of the port trunk.
The AT-S39 management software offers two load distribution methods.
They are:
❑ Source Address (SA) Trunking
❑ Source Address / Destination Address (SA/DA) Trunking
Let’s first take a look at the SA method. When a switch receives a packet
from a network node, it examines the destination address to determine
on which switch port, if any, the packet should be transmitted. If the
packet is destined for a port trunk, the switch then examines the source
address of the packet. If this is the first packet from the source node to
be transmitted over a port trunk, the switch assigns the source address
to one of the trunk links. All subsequent packets from the source node
are sent out the assigned data link of the trunk.