3Com 4007, Руководство по внедрению, Страница: 343 / 684

Long Custom Filter Example 343
Name “IP XNS ticker bcast filter”
# Assign this filter in the multicast path
# of a port only--this is very important.
#
# XNS FILTERING SECTION
#
pushField.a
0 # Apply
pushLiteral.a 0xffffffffffff# filter
ne # only on broadcast traffic
accept #
pushField.w
12 # Get the type field of the packet and
# place it on top of the stack.
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
#
# IP FILTERING SECTION
#
pushField.w 12 # Get the type field of the packet and
# place it on top of the stack.
pushLiteral.w 0x0800 # Put the type value for IP 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 (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.
and # Compare if IP and in range.
or # Determine if the type field is either
# XNS or IP.
not # Discard if (IP & in range) and (XNS & in
# range).