Cabletron Systems SmartSwitch 6000 User Manual - Packet Distribution
Introduction
1-2
Packet Distribution
Packet distribution is based on hardware family type:
SmartSwitch 6000
Packet distribution among the ports in the group is accomplished by adding the
last two bytes of the
destination
and
source
MAC addresses and then applying
the modulus operator to the sum using the number of active ports in the group.
The remainder, which falls into the range of the number of ports in the group, will
dictate which port will be used by the address. This gives a random distribution
of the packet load, but insures that the same destination-source flow always goes
out the same port. This alleviates the possibility of out-of-order packets.
SmartSwitch 9000
Packet distribution is accomplished by applying the modulus operator to the last
four bytes of the
destination
MAC addresses using the number of active ports in
the group. The remainder, which falls into the range of the number of ports in the
group, will dictate which port will be used by the address.
Modulus Examples
Ports contained in the trunk are labeled from zero (0) to one less than the number
of ports in the group. For example, if the physical ports in the group are
1 3 5 7 9, packet distribution would be based on the trunking port number
assigned. Trunking port numbers are 0 1 2 3 4.
The modulus operator divides the first number by the second number and yields
a whole number remainder:
(sum of addresses) modulus (number of trunk ports) = remainder
For example:
5 mod 4 = 1
(Four goes into five once with a remainder of one)
4 mod 5 = 4
(Five goes into four no times with a remainder of four)
The remainder is the useful number that will fall between zero (0) and one less
than the number of trunk ports. This remainder will dictate which trunk port is
used to send the traffic by matching it to the trunking port number.