AL103 Revision 1.0
3.7.3 Trunk Port Assignment
The maximum number of trunks for the AL103 is two. The Port Configuration I registers provide
the ability to designate a port to be a member of a trunk. The trunk can consist of up to four trunk
ports. A trunk group must consist of either the top four ports or the bottom four ports, for example a
trunk can consist of port 0 through port 3 or port 4 through port 7. Each trunk port’s number is in
sequence of 00, 01, 10, and 11 corresponding to the order of port of the devices. For example, port
1 and 5 are 01 (See Figure 4).
AL103
Ports
1
2
3
4
5
6
7
0
Trunk Port 1
Trunk Port 0
Figure 4
Trunk Port Numbering
3.7.4 Port Based Trunk Load Balancing
For port-based load balancing, a trunk port must be assigned to each port for all defined trunks. The
port assignment is done by programming Port to Trunk Port Registers (2E to 35). A port assignment
worksheet is provided at the back of the data sheet. It is recommended that ports be evenly
distributed among all trunk ports to prevent overloading any single trunk port.
Port Based Load Balancing Set up Example
Note: Register bits are reference by X.Y, where “X” is the register number and “Y” is the bit
number. Appendix I and II provide a worksheet for port to trunk port and VLAN assignment.
The example is designing an 8-port switch with a 3-port based loading trunk. The desired trunk
ports are 5, 6, and 7. We want to assign port 0 to trunk port 5, port 1 and 3 to trunk port 6, and port
2 and 4 to trunk port 7.
1. The Port Configuration I register bits 15.9, 16.9, and 17.9 are set to 1. This assigns
ports 5, 6, and 7 as a trunk port.
2. Assign port 0 to trunk port 5, port 1 and 3 to trunk port 6, and port 2 and 4 to trunk
port 7. Therefore, set port to trunk port register bits.
2E.2= 0, 2E.3 =1
2F.2= 1, 2F.3 =0
30.2= 1, 30.3 =1
31.2= 1, 31.3 =0
32.2= 1, 32.3 =1
9/00
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