4.7.4 IPX HEADER FILTERS
There is a single IPX header filter that can control the forwarding of packets from each port. The user can select if this filter is applied to packets received from either or both ports.
The filter can have up to 128 entries. If IPX filtering is active, then any packets received are checked against the filter table before processing by the Router. The operation of the IPX filter does not effect RIP and SAP packets as they are processed directly by the Router.
It should be noted that the filter table is sequentially searched for each IPX packet received until a match is found. A filter table with multiple entries will impose a significant processor loading and a corresponding drop in performance.
In most cases IPX conversations require packets to be passed in both directions. Stopping packet flow in one direction will stop any conversation taking place. It may not be necessary to use filters in both directions.
The filter table is configured depending upon which networks, nodes and sockets are expected to be found connected to each port. The actual comparison of the packet source or destination address in the IPX Header to the filter table changes depending upon which port the packet is received from. If network 45 is set by the filter as connected to Port A then packets received from Port A would have the IPX header source network number compared to the entry for network 45. Packets received from Port B would have the IPX header destination network number compared to 45.
Each of the seven fields can be set to pass ALL. The result of any entry can be set to PASS or FAIL. If the search reaches the end of the table with no match then the result is an automatic FAIL.
MENU SELECTION | DESCRIPTION |
ADD | A new entry may be added to the end |
| of the Table or after an entry |
EDIT | To edit an entry, selecting the |
| relevant line number entering |
| required amendments. |
DELETE | Enter the line number to delete. |
CLEAR | To delete the entire table. |
NAME | Define a name for this filter table |
LIST PARAMETER | DESCRIPTION |
LINE | The Line Number of the Filter Table |
| entry used to specify an entry to be |
| changed or deleted. |
Echo LANlink Router Option User Manual | Issue 1.0 04 December 1997 Page 40 of 59 |