Cabletron Systems 1800 - Manual (Page 236)

15-4 SmartSwitch 1800 4. 0 User G uide, Rev 01
Figure 15-2 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 F000 . The binary "ANDing" is as
follows:
Value: 0001001000110100
Mask: 1111000000000000
AND Result: 0001000000000000
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 , Mask = F000 : Packet field = 1237 , Mask = F000 :
Binary value: 0001001000110011 Value: 0001001000110111
Mask: 1111000000000000 Mask: 1111000000000000
AND Result: 0001000000000000 AND Result: 0001000000000000
IPX Filter D efinitions
* Filter Category 1–S AP
* Filter ID 1
A Filter Name filter_zxy
B Service Typ e Value 0004
C Service Typ e Mas k 000f
D Server Name s erver_123
E Network Ad dres s V alu e ff00ac00
F Network Ad dres s Mask ffff0000
G Nod e Ad dres s V alu e 10ac45000001
H Nod e Ad dres s Mask ffffff000000
I Socket Add ress Value 4000
J Socket Add ress Mask f000
Op tion :