15 Allowed ISUP Message Type Screen Configuration
Chapter 15, Allowed ISUP Message Type Screen Configuration, contains the procedures necessary to configure allowed ISUP message type screens.
Introduction
The ISUP Message Type screen identifies which ISUP messages, using the ISUP message type, that are allowed into the EAGLE. The gray shaded areas in Figure 15-4 shows the fields of the SS7 message that are checked by the ISUP Message Type screening function.
Gateway Screening Actions
The Gateway Screening process stops with this screen. The nsfi parameter value can only be stop.
If a match is not found, the message is discarded.
actname parameter value, the message is processed according to the gateway screening stop actions that are assigned to the gateway screening stop action set.
- If the
rdct(redirect) gateway screening stop action is specified, the message is diverted from the original destination and sent to another destination with the Database Transport Access feature, specified by global title translation, for further processing. - If the
cncfgateway screening stop action is specified, the PIP parameter in the incoming ISUP IAM message is converted to the GN parameter. The GN parameter in the incoming ISUP IAM message is converted to the PIP parameter. The message is then sent to the node specified by the DPC in the routing label in the message. For more information on the Calling Name Conversion Facility feature, see Calling Name Conversion Facility (CNCF) Configuration. - If the
tlnpgateway screening stop action is specified, ISUP IAMs that pass gateway screening are processed either by the ISUP NP with EPAP feature (if the ISUP NP with EPAP feature is enabled and turned on) or by the Triggerless LNP feature (if the Triggerless LNP feature is turned on). The ISUP NP with EPAP feature is discussed in more detail in G-Port User's Guide. The Triggerless LNP feature is discussed in more detail in ELAP Administration and LNP Feature Activation Guide. - If the
tinpgateway screening stop action is specified, ISUP IAMs that pass gateway screening are intercepted by the Triggerless ISUP based Number Portability (TINP) feature and converted to include the routing number (RN) if the call is to a ported number. The TINP feature is discussed in more detail in G-Port User's Guide. - If the
tif,tif2, ortif3gateway screening stop actions are specified, TIF processing is applied to the message. - If the
sccpgateway screening stop action is specified, MTP routed SCCP UDT/XUDT are forwarded to the service modules for further processing.
TUP Message Screening
TUP messages are screened using the Allowed ISUP Message
Type screen. The TUP protocol is an obsolete predecessor to the ISUP protocol
that remains in use in some areas. To screen for TUP messages, a screen set
must be defined to screen for messages containing the service indicator value
of 4. This is accomplished by defining an allowed SIO screen in the screen set
containing the
si=4 parameter.
Since both ISUP and TUP messages are screened using the allowed ISUP message type screen, it is recommended that the screen set contain an allowed SIO screen to screen for ISUP messages, messages containing the service indicator value of 5. Each of these entries in the allowed SIO screen should have separate next screening functions. This allows the screening rules after the allowed SIO screen to have two separate streams, one that ends with screening ISUP messages, the other that ends with screening TUP messages.
The TUP messages can be screened for point codes before the allowed SIO screen with the allowed and blocked OPC screens, and after the SIO screen with the allowed and blocked DPC screens. However, if the screen set does not contain an allowed SIO screen that screens for TUP messages (messages with the service indicator value of 4), the message will be treated by the allowed ISUP message type screen as an ISUP message.
The following commands show how a screen set can be provisioned to screen for TUP and ISUP messages.
ent-scr-isup:sr=is01:isupmt=10:nsfi=stop
ent-scr-isup:sr=tu01:tupmt=1:nsfi=stop
ent-scr-dpc:sr=dpc4:ni=1:nc=2:ncm=3:nsfi=isup:nsr=tu01
ent-scr-dpc:sr=dpc5:ni=7:nc=1:ncm=0:nsfi=isup:nsr=is01
ent-scr-sio:sr=si02:nic=2:pri=0:si=4:nsfi=dpc:nsr=dpc4
ent-scr-sio:sr=si02:nic=2:pri=0:si=5:nsfi=dpc:nsr=dpc5
ent-scrset:scrn=ist2:nsr=si02:nsfi=sio
In this example screen set configuration, messages are
screened by the allowed SIO screen
si02 for either ISUP or TUP messages.
ISUP messages are further screened by the allowed DPC screen
dpc5 and TUP messages are screened by
the allowed DPC screen
dpc4. The ISUP messages containing the
ANSI point code 001-002-003 are passed onto the allowed ISUP screen
is01. The TUP messages containing the
ANSI point code 007-001-000 are passed onto the allowed ISUP screen
tu01.
Note:
The gateway screening rules are entered in reverse of the order that the screening process takes place.Allowed ISUP Message Type Screening Actions
Figure 15-1 through Figure 15-3 show the screening actions of the allowed ISUP message type screen.
Figure 15-1 Allowed ISUP Message Type Screening Actions - Sheet 1 of 3
Figure 15-2 Allowed ISUP Message Type Screening Actions - Sheet 2 of 3
Figure 15-3 Allowed ISUP Message Type Screening Actions - Sheet 3 of 3
Figure 15-4 Allowed ISUP Message Type Screening Function
Adding an Allowed ISUP Message Type Screen
This procedure is used to add an allowed ISUP message
type (ISUP) screen to the database using the
ent-scr-isup command. The parameters
used by the
ent-scr-isup command are shown in the
Gateway Screening Attributes
section. The general rules that apply to configuring gateway screening entities
are shown in the
Gateway Screening Configuration
section.
Since both ISUP and TUP messages are
screened by the allowed ISUP message type screen, the
ent-scr-isup command contains a
parameter for the ISUP message type (isupmt)
and a parameter for the TUP message type (tupmt). Only one of these parameters can be specified
for the allowed ISUP screen being entered into the database. The
isupmt parameter should be specified
in screen sets that contain allowed SIO screens that are screening messages for
the service indicator value of 5 (SI=5). The
tupmt parameter should be specified in
screen sets that contain allowed SIO screens that are screening messages for
the service indicator value of 4 (SI=4). If you wish to screen for TUP
messages, make sure that the screen set being configured contains an allowed
SIO screen that screens messages for the service indicator value of 4 (SI=4).
If you do not do this, the EAGLE will treat the message as an ISUP message,
even if the message contains the service indicator value of 4.
Table 15-1 Example Gateway Screening Allowed ISUP Configuration Table
| Screening Reference | ISUPMT | NSFI | ACTNAME |
|---|---|---|---|
| isp1 | 135 | stop | CR |
| isp2 | 139 | stop | CR |
| Screening Reference | TUPMT | NSFI | ACTNAME |
| tup1 | 100 | stop | CR |
Figure 15-5 Add an Allowed ISUP Message Type Screen - Sheet 1 of 3
Figure 15-6 Add an Allowed ISUP Message Type Screen - Sheet 2 of 3
Figure 15-7 Add an Allowed ISUP Message Type Screen - Sheet 3 of 3
Removing an Allowed ISUP Message Type Screen
This procedure is used to remove an allowed ISUP message
type (ISUP) screen from the database using the
dlt-scr-isup command. The parameters
used by the
dlt-scr-isup command are shown in the
Gateway Screening Attributes
section. The general rules that apply to configuring gateway screening entities
are shown in the
Gateway Screening Configuration
section.
Since both ISUP and TUP messages are screened by the
allowed ISUP message type screen, the
dlt-scr-isup command contains a
parameter for the ISUP message type (isupmt)
and a parameter for the TUP message type (tupmt). Only one of these parameters can be specified
for the allowed ISUP screen being removed from the database.
The example in this procedure removes the allowed ISUP
screen
isp2 from the database.
The allowed ISUP screen can be referenced by one of the following screens.
- Allowed SIO
- Allowed DPC
- Blocked DPC
Verifying the Gateway Screening Configuration
Enter the following commands to verify that none of these screens reference the allowed ISUP screen being removed from the database.
-
rtrv-scr-sio:nsfi=isup -
rtrv-scr-dpc:nsfi=isup -
rtrv-scr-blkdpc:nsfi=isup
Gateway Screening Configuration Procedures
To change the NSFI of any of these screens, perform to one of these procedures.
Figure 15-8 Remove an Allowed ISUP Message Type Screen
Changing an Allowed ISUP Message Type Screen
This procedure is used to change the attributes of an
allowed ISUP message type (ISUP) screen in the database using the
chg-scr-isup command. The parameters
used by the
chg-scr-isup command are shown in the
Gateway Screening Attributes
section. The general rules that apply to configuring gateway screening entities
are shown in the
Gateway Screening Configuration
section.
The example in this procedure is used to change the ISUP
message type 135 for the allowed ISUP screen
isp1 to 075 and to redirect the MSU
for the DTA feature.
Figure 15-9 Change an Allowed ISUP Message Type Screen - Sheet 1 of 2
Figure 15-10 Change an Allowed ISUP Message Type Screen - Sheet 2 of 2