AL103 Revision 1.0
3.7.5 MAC Based Load Balancing
For MAC address based load balancing, there is no need to assign a port to a trunk port. The AL103
dynamically assigns MAC addresses to the trunk port. MAC address based trunks can consist of
two, three, or four trunk ports. The bits are chosen for their randomness. The statistically random
bits will ensure good load balancing among all trunk-ports.
The following is a procedure to set up the MAC based load trunk.
1. Select MAC address load trunking by setting bit 00.3 to “1.”
2. Select the trunk ports using Port Configuration Register I bit 9.
3. Assign the ports and the trunk port to the same VLAN using register 1E to 2C.
4. When the number of trunk ports is four, the following steps are not required. If the
number of trunk ports are two or three, set register bit 2D.8 (L2MAP) to “1.”
5. Set the TrunkMap1 or TrunkMap0 in register bits 7 through 0. These bits indicate
the mapping of trunk ports. For example, if ports 0 and 1 are used as trunk ports,
then set the bits 2D.0 and 2D.1 to “1.” If ports 5 and 7 are used as trunk ports, set
bits 2D.5 and 2D.7. The trunk port mapping and the trunk member bits set in Port
Configuration I register must match.
6. Finally, select the algorithm for MAC based loading. Set register 2D.10 to “1” for
source address only, and “0” for the combination of source and destination
addresses.
The port VLAN grouping should include all the trunk ports. Since the AL103 will assign the port
by MAC addresses, frames from any single port may be routed to any trunk ports.
MAC Based Load Balancing Example
The desired trunk port is 4, 5, 6, and 7. Therefore, the port configuration register bits 15.9, 17.9,
19.9, and 1B.9 are set to “1.” Select MAC address loading by setting bit 00.3 to “1.”
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