3Com 4007, Implementation Manual, Page: 349 / 684

Long Custom Filter Example 349
Name “Optimized IP XNS ticker bcast filter”
# Assign this filter in the multicast path
# of a port only--this is very important.
#
# XNS FILTERING SECTION (Assuming more XNS traffic)
pushField.a 0 #
pushLiteral.a 0xffffffffffff#
ne #
accept #
pushField.w
12 # Get the type field of the packet and
# place it on top of the stack.
pushTop # push copy of type
pushLiteral.w
0x0600 # Put the type value for XNS on top of
# the stack.
eq # If the two values on the top of the
# stack are equal, then return a non-zero
# value.
pushLiteral.w 0x76c # Put the lowest socket value on top of
# the stack.
pushField.w 30 # Put the value of the socket from the
# packet on top of the stack.
ge # Compare if the value of the socket is
# greater than or equal to lower bound.
pushLiteral.w 0x0898 # Put the highest socket value on top of
# the stack.
pushField.w 30 # Put the value of the socket from the
# packet on top of the stack.
lt # Compare if the value of the socket is
# less than the upper bound
and # “and” together with “ge” and “lt” test
# to determine if the socket value is
# “within” the range. If it is, place a
# “one” on the stack
#
and # Compare if XNS & in range
reject # reject if XNS and in range
#
# IP FILTERING SECTION
#
# The type field of the packet was
# place on top of the stack by the PushTop command.
#
pushLiteral.w
0x0800 # Put the type value for IP on top of
# the stack.
ne # not IP
accept # go no further
#
pushLiteral.w 0x76c # Put the lowest socket value on top of
# the stack (1900).
pushField.w 24 # Put the value of the socket from the
# packet on top of the stack.
ge # Compare if the value of the socket is
# greater than or equal to lower bound.
pushLiteral.w 0x0898 # Put the highest socket value on top of
# the stack (2200).
pushField.w 24 # Put the value of the socket from the
# packet on top of the stack.
lt # Compare if the value of the socket is
# less than the upper bound
and # “and” together with “ge” and “lt”.
# Test to determine if the socket value is
# “within” the range. If it is in range,
# place a “one” will on the stack.
not # Discard (IP & in range)