3Com LANPLEX 2500 Operation Manual page 71

7-14 C 7: U - P F
HAPTER SER DEFINED ACKET ILTERING
table in Figure 7-9 on page 7-75 is for LANplex 2500 system Engineering
Group A.
2 After setting up the address groups, generate the following filter:
if (source address group mask AND destination address group
mask) = 0 then discard packet
The expressions used in this example filter can be separated as follows:
Expression 1: source address group mask AND destination address group
mask
Operand 1 is the source address group mask.
Operand 2 is the destination address group mask.
Operator is bit-wise AND.
Expression 2: Expression 1 result = 0
Operand 1 is the result of Expression 1.
Operand 2 is the value 0.
Operator is equal.
The filter would be installed on the receive paths of the user group ports as
shown in Figure 7-10. The packet is examined as soon as it is received by
the port and discarded if the destination address of the packet is not in the
same address group as the source address of the packet.