Allied Telesis AT-S62 - Manual (Page 145)

AT-S62 Management Software Menus Interface User’s Guide
Section I: Basic Operations 145
As an example, assume you created a static or LACP aggregate trunk of
Ports 7 to 14 on a switch. The table below shows the mappings of the
switch ports to the possible values of the last three bits of a MAC or IP
address.
Now assume you selected source MAC address as the load distribution
method and that the switch needed to transmit over the trunk a packet with
a source MAC address that ended in 9. The binary equivalent of 9 is 1001,
making the last three bits of the address 001. An examination of the table
above indicates that the switch would use Port 8 to transmit the frame
because that port is mapped to the matching bits.
The same method is used for the two load distribution methods that
employ both the source and destination addresses. Only here the last
three bits of both addresses are combined by an XOR process to derive a
single value which is then compared against the mappings of bits to ports.
The XOR rules are as follows:
0 XOR 0 = 0
0 XOR 1 = 1
1 XOR 0 = 1
1 XOR 1 = 0
As an example, assume that you had selected source and destination
MAC addresses for the load distribution method in our previous example,
and that a packet for transmission over the trunk had a source MAC
address that ended in 9 and a destination address that ended in 3.
The binary values would be:
9 = 1001
3 = 0011
Applying the XOR rules above on the last three bits would result in 010. A
examination of the table above shows that the packet would be transmitted
from port 9.
Port trunk mappings on an AT-8500 Series switch can consist of up to
eight ports. This corresponds to the maximum number of ports allowed in
a static trunk and the maximum number of active ports in an LACP trunk.
(Inactive ports in an LACP trunk are not applied to the mappings until they
transition to the active status.)
Last 3 Bits 000
(0) 001
(1) 010
(2) 011
(3) 100
(4) 101
(5) 110
(6) 111
(7)
Trunk Ports 7 8 9 10 11 12 13 14