Gateway Screening Configuration

Gateway screening can be configured in a variety of ways, depending on the criteria you wish to screen the messages for. The examples used in these procedures are based on seven example configurations (Figure 2-3 through Figure 2-9). Each example configuration shows the screening order used by the EAGLE, with the screening criteria for each screen, and the order that these screens are added to the database to achieve the screening order, with the command entry required to enter the screening criteria into the database.

Each procedure adding a gateway screening entity to the database contains a table showing the parameters and the data used for the command examples.

Note:

The gateway screening rules table can contain a maximum of 362,700 rules.

The EAGLE can contain a maximum of 255 screen sets.

Each screen set can contain a maximum of 4,000 rules, however the total number of rules contained in all the screen sets cannot exceed 362,700.

These general rules apply to configuring gateway screening entities in the database. Each procedure contains any rules that are specific to that procedure.

1. The gateway screening feature must be turned on before gateway screening entities can be added to the database.

   Verify this by entering the rtrv-feat command. If the gateway screening feature is off, it can be turned on by entering the chg-feat:gws=on command.

   Note:

   Once the gateway screening feature is turned on with thechg-feat command, it cannot be turned off
2. A TSM running the GLS application GPL must be configured in the database with the ent-card:type=tsm:appl=gls:loc=<TSM Card Location> command.

   Verify this with the rtrv-card command.

3. Changing or removing an existing gateway screening entity will change the screening order for the messages on the linkset.

   Verify the new screening order before changing or removing any gateway screening entities.

4. If the screen set being added to the database includes existing screening references, messages in the linkset being screened will be screened against all entries in those screening references.

   This could allow a message into the EAGLE that was not supposed to be allowed in, or a message blocked from the EAGLE that is supposed to be allowed in. Verify the contents of existing screening references to make sure that you want all messages in the linkset screened against all entries in the existing screening references.

5. The gateway screening entity specified by the nsfi and nsr parameters must be in the database.
6. If the nsfi and nsr parameters do not reference an existing screening entity, the nsfi parameter must be set to stop and the nsr parameter cannot be specified.

   When the nsfi parameter is set to stop, the gateway screening process stops at the specified screen.

7. The actname parameter, specifying the gateway screening stop action set assigned to the screen, can only be specified with the nsfi=stop parameter.

   Caution:

   When Gateway Screening is in the screen test mode, as defined by the linkset parametersgwsa=off andgwsm=on, any action in the gateway screening stop action set specified by theactname parameter at the end of the gateway screening process will be performed.
8. The word SEAS cannot be used as a value for the scrn parameter of the ent-scrset, dlt-scrset, and chg-scrset commands.

   The word SEAS is used in the rtrv-ls command output, in the SCRN field, to show gateway linksets created on the SEAS interface. A gateway linkset can only be configured from a SEAS terminal and not from an EAGLE terminal. Gateway linksets can only be displayed from the SEAS interface.

9. When removing gateway screening entities from the database, the specified entity cannot be removed if it is referenced by other gateway screening entities.

   If it is referenced by other gateway screening entities, either the nsfi parameter in those gateway screening entities must be changed to stop, or the nsfi and nsr parameters in the those gateway screening entities must be changed to reference other gateway screening entities.

10. Point code values containing all zeros, shown in the following list, cannot be specified for any gateway screening command:
    • ANSI Point Code - 000-000-000
    • ITU-I Point Code - 0-000-0
11. A screening reference may contain both 14-bit and 24-bit ITU national point codes, only if the internal values of these point codes are not the same.

    For example, the 14-bit ITU national point code 1 (npc=1) and the 24-bit ITU national point code 000-000-001 (msa=0, ssa=0, sp=1) cannot be specified for the same screening reference as both of these point codes have the same internal value. This would also apply to using the asterisk as a point code value. The npc=* and the msa=*, ssa=*, sp=* parameters cannot be specified in the same screening reference.

12. If the last entry in the specified screening reference is removed from the database, the screening reference is removed from the database.

    If an attempt is made to display that specified screening reference name (for example, entering the rtrv-scr-opc:sr=iec command after removing the last entry in the allowed OPC screen IEC), the output shows that the specified screening reference name is not in the database, as shown in this example. the following error message is displayed showing that the specified screening reference name could not be found in the database.

    E2573 Cmd Rej: SR or NSR does not reference an existing SR
    

13. The EAGLE screens messages in a hierarchical fashion.

    For example, allowed OPC screens are checked before blocked OPC screens; blocked OPC screens are checked before allowed SIO screens, and so on. The gateway screening entities must be entered in reverse of the order that the screening process takes place (see Figure 2-2). To add gateway screening entities into the database, the first entity to be entered must be the entity that you want to stop screening the message on. The other entities follow in the proper order and the screen set is the last entity to be added into the database. The screen set entity must be in the database for gateway screening to take place. Table 2-8 The following lists shows the order of the MTP gateway screening process and the SCCP gateway screening process and the order that these gateway screening entities must be entered into the database.

    Table 2-8 Gateway Screening Process and Provisioning Order

    MTP Gateway Screening Order		SCCP Gateway Screening Order
    Screening Order	Order of Entry into the Database	Screening Order	Order of Entry into the Database
    1. Screen Set 2. Allowed OPC 3. Blocked OPC 4. Allowed SIO 5. Allowed DPC 6. Blocked DPC 7. Allowed DESTFLD or Allowed ISUP*	1. Allowed DESTFLD or Allowed ISUP* 2. Blocked DPC 3. Allowed DPC 4. Allowed SIO 5. Blocked OPC 6. Allowed OPC 7. Screen Set	1. Screen Set 2. Allowed OPC 3. Blocked OPC 4. Allowed SIO 5. Allowed DPC 6. Blocked DPC 7. Allowed CGPA 8. Allowed TT 9. Allowed CDPA 10. Allowed AFTPC	1. Allowed AFTPC 2. Allowed CDPA 3. Allowed TT 4. Allowed CGPA 5. Blocked DPC 6. Allowed DPC 7. Allowed SIO 8. Blocked OPC 9. Allowed OPC 10. Screen Set
    * The allowed ISUP screen can contain ISUP and TUP message types.

    Using the ent-ls or chg-ls commands, the screen set can then be assigned to a linkset and all messages on that linkset are screened for acceptance into the network.

    When the copy-disk or copy-tbl commands are issued, the database on disk is locked. A DB Timeout alarm is generated due to the LIM cards inability to download GWS data. Once the command completes, the LIM card is able to download the dataset.

Figure 2-2 The Gateway Screening Process