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How Filter Masks Work
14-4
I PX Filter Definition s
* Filter Category
* Filter ID
A Filter Name
B Service Type V alu e
C Service Type Mask
D Server N ame
E Network Add ress Value
F Network Add ress Mask
G Node Add ress Value
H Node Add ress Mask
I
Socket A ddress Value
J Socket A ddress Mas k
Option:
Figure 14-2 IPX SAP Filter Record
Each IPX filter parameter except
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
follows:
Value:
Mask:
AND Result:
The mask will also be ANDed to its corresponding field in each IPX packet as deter-
mined by
IPX Filter
Applications. 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
Binary value:
0001001000110011
Mask:
1111000000000000
AND Result:
0001000000000000
1–S AP
1
filter_zxy
0004
000f
s erver_123
ff00ac00
ffff0000
10ac45000001
ffffff000000
4000
f000
[A],[A],[E],[F],[B]
and
Filter Name
and the mask is
1234
0001001000110100
1111000000000000
0001000000000000
, Mask =
:
Packet field =
F000
Value:
Mask:
AND Result:
from Main Menu
is assigned a value and
Server Name
. The binary "ANDing" is as
F000
, Mask =
1237
F000
0001001000110111
1111000000000000
0001000000000000
Frame Relay Module 4.0 User Guide, Rev 01
:
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