Allied Telesis AT-S39 - Manual (Page 87)

AT-S39 User’s Guide
87
So now let’s look at the SA/DA method. A switch using the SA/DA
method creates a matrix of the source and destination MAC addresses
and then uses the matrix to determine which port in the trunk a frame is
to be transmitted. With this method, packets from a particular source
node might be sent over different data links in a trunk when sent to
different destination addresses.
So let’s take a look at how this might look in practice. Assume that you
configured Switch #2 in our example for SA/DA. The result might be
something similar to that shown in Table 2.
Even though there is only one source, all the data links in the trunk are
used. For instance, if the server needed to send a packet to Workstation
C, by referring to the matrix Switch #2 would use Port 3 of the trunk to
transmit the packet from that particular source MAC address to Switch
#1.
As you can see, the SA/DA method is useful when a port trunk needs to
send packets from one source node to many destination nodes,
something that the SA method is not suited for. Additionally, the SA/DA
method is also valid when sending from many source nodes to one
destination node, or from many sources to many destinations.
The table below shows a possible matrix for a port trunk of three data
links using the SA/DA method, handling traffic from four sources to four
destinations.
Table 2 Trunk Port Assignments in an SA/DA Matrix
Destinations MAC Addresses
Source MAC Address
Workstation
A
00A0EE 2313A3
Workstation
B
00A134 1A9032
Workstation
C
00A301 9083B2
Workstation
D
001B21 87C6D6
Server
00B012 DA0231 2 1 3 1