Cabletron Systems MMAC-Plus 9F116-01, User Manual, Page: 232 / 420

12-4 FRX/FRM 3. 3 User G uide, Rev 04
Figure 12-2 IPX SAP Filter Record
[A], [A],[E], [F],[B] from Main Menu
How Filter Masks Work
Each IPX filter parameter except
Filter Name
and
Server Name
is assigned a value and
an associated mask. The mask determines (by the process described below) whether
the filter will be applied to the packet.
The binary bits of the mask will be "ANDed" (0+0=0, 0+1=0, 1+1=1) to the value, as
in this example:
Assume the value (hex) is
1234
and the mask is
5678
. The binary "ANDing" is as
follows:
Value: 0001001000110100
Mask: 0101011001111000
AND Result: 0001001000110000
The mask will also be ANDed to its corresponding field in each IPX packet as deter-
mined by IPX Filter Applications (described later in this chapter). This result will be
compared to the AND result of the configured value and mask. If the two results
match, the filter will be applied. This process allows a number of packet field values
to match the AND result of the mask and value; for example:
Packet field =
1233
, Mask =
5678
:Packet field =
1237
, Mask =
5678
:
Binary value:
0001001000110011
Value:
0001001000110111
Mask:
0101011001111000
Mask:
0101011001111000
AND Result:
0001001000110000
AND Result:
0001001000110000
IPX Filter Defin itions
* Filter C ategory 1–SAP
* Filter I D 1
A Filter N ame filter_zxy
B S ervice Type Value 0004
C S ervice Type Mask 000f
D S erver Name server_123
E N etw ork A ddress Value ff00ac00
F N etw ork A ddress Mas k ffff0000
G N ode A ddress Value 10ac45000001
H N ode A ddress Mas k ffffff000000
I S ock et Ad dres s V alu e 4000
J S ock et Ad dres s Mask f000
Option: