Configuring the Restricted Linkset Option

This procedure is used to configure the restricted linkset option using the chg-ss7opts command with the lsrestrict parameter. The lsrestrict parameter has two values:

on – enables the lsrestrict option
off – disables the lsrestrict option.

When a large linkset (a linkset containing more than three links) first becomes available, there may not be enough available links to carry the normal amount of traffic on the linkset. The EAGLE sends response method TFA/TFRs when the number of links within a linkset, specified by the tfatcabmlq parameter for that linkset, are active and available to carry traffic. This was designed to prevent congestion on the newly available linksets. Internally in the EAGLE, if a single link within a lower cost route is active, the EAGLE attempts to route traffic over the lower cost route. If no traffic or small amounts of traffic are arriving due to the issuance of a TFR, then no congestion should occur.

However, this behavior applies only to traffic destined for remote nodes and not to traffic destined for the EAGLE itself. Typically, messages that are global title routed are destined for the EAGLE's true, secondary or capability point code. The existing congestion prevention mechanism does not prevent traffic destined for EAGLE to be controlled by the linkset’s tfatcabmlq parameter. This is because TFx messages have an affected point code field that is the far end destination point code and not the EAGLE's point code, so traffic destined for EAGLE continues to arrive for the restricted destination. It is not feasible to place EAGLE's point code in the affected destination field as this would affect all traffic destined for EAGLE and not just traffic over a specific route.

With the lsrestrict=off option, the EAGLE continues to route traffic in this manner.

The lsrestrict=on option enhances the EAGLE’s existing behavior of the linkset’s tfatcabmlq parameter and allow the state of the route combined with the cost value of the route to determine the preferred route to use.

Turning the lsrestrict option on changes the way the EAGLE routes messages by using the state of the route along with the cost of the route to determine the preferred route to use. With this option on, the preferred route is not the absolute lowest cost available route in the routeset. A route is considered available if its status is either Allowed or Restricted. If the state of the absolute lowest cost route in the routeset is Restricted, the preferred route is the lowest cost route in the routeset whose status is Allowed. Make sure that you wish to have the EAGLE route messages in this manner before turning the lsrestrict option on.

In previous releases, a C linkset's tfatcabmlq parameter is not configurable and set to 1 (the linkset is allowed when the first link is available). This is because the C linkset is designed for message trafficking between the mate STP's and would allow these messages to be transferred as soon as the first link in the C linkset was available. The lsrestrict=on option allows the tfatcabmlq parameter value for a C linkset to be from 0 to 16, just as any other linkset.

With the lsrestrict=off option, the tfatcabmlq parameter value for a C linkset is set to 1 and cannot be changed.

When a linkset that was previously prohibited becomes restricted (that is, the number of links that became available is less than the required number of links as specified by the linkset’s tfatcabmlq parameter) the following events occur when the lsrestrict option is on:

The EAGLE 5 ISS does not broadcast TFAs.
Point codes that were previously prohibited and use the linkset as a lower cost route are marked restricted. The EAGLE continues to broadcast TFRs.
Point codes that were previously restricted and use the linkset as a least cost route remain restricted. The EAGLE does not broadcast any TFx message. For these point codes, RSRT will respond to RSP messages with a TFR, and will not respond to RSR messages.
The EAGLE marks the linkset as restricted.
If a higher cost route is available, the EAGLE routes the traffic over the higher cost route.

Once the required number of links are available for the linkset, the following events occur when the lsrestrict option is on:

The EAGLE marks the previously prohibited/restricted point codes as allowed that use the linkset as a lower cost route (unless the point code's nonadjacent status is prohibited).
The EAGLE does not broadcast TFAs for the newly allowed point codes, but responds to RSR/RSP messages with a TFA.
The EAGLE marks the linkset as allowed. The appropriate changeback procedures are performed and traffic is processed normally.

Canceling the RTRV-LS Command

Because the rtrv-ls command used in this procedure can output information for a long period of time, the rtrv-ls command can be canceled and the output to the terminal stopped. There are three ways that the rtrv-ls command can be canceled.

Press the F9 function key on the keyboard at the terminal where the rtrv-ls command was entered.
Enter the canc-cmd without the trm parameter at the terminal where the rtrv-ls command was entered.
Enter the canc-cmd:trm=<xx>, where <xx> is the terminal where the rtrv-ls command was entered, from another terminal other that the terminal where the rtrv-ls command was entered. To enter the canc-cmd:trm=<xx> command, the terminal must allow Security Administration commands to be entered from it and the user must be allowed to enter Security Administration commands. The terminal’s permissions can be verified with the rtrv-secu-trm command. The user’s permissions can be verified with the rtrv-user or rtrv-secu-user commands.

For more information about the canc-cmd command, go to Commands User's Guide.

Display the existing value for the lsrestrict parameter by entering the rtrv-ss7opts command. This is an example of the possible output.
```
rlghncxa03w 06-10-17 16:02:05 GMT  EAGLE5 36.0.0

SS7 OPTIONS
-----------------------
LSRESTRICT          off
```
Note:
The rtrv-ss7opts command output contains other fields that are not used by this procedure. If you wish to see all the fields displayed by the rtrv-ss7opts command, see the rtrv-ss7opts command description in Commands User's Guide.

Note:
If the lsrestrict parameter value in step 1 is off, skip steps 2 and 3, and go to step 4.

Display the linksets in the database by entering the rtrv-ls command. This is an example of the possible output.

rlghncxa03w 06-10-10 11:43:04 GMT EAGLE5 36.0.0
                                 L3T SLT              GWS GWS GWS
LSN          APCA   (SS7)  SCRN  SET SET BEI LST LNKS ACT MES DIS SLSCI NIS
e1e2         001-207-000   none  1   1   no  B   6    off off off no    off
ls05         002-009-003   scr2  1   1   no  C   4    on  off on  no    off
ls1305       000-005-000   none  1   1   no  A   1    off off off no    off
ls1307       000-007-000   none  1   1   no  A   1    off off off no    off
e1m1s1       001-001-001   none  1   1   no  A   7    off off off no    off
e1m1s2       001-001-002   none  1   1   no  A   7    off off off no    off

                                 L3T SLT              GWS GWS GWS
LSN          APCI   (SS7)  SCRN  SET SET BEI LST LNKS ACT MES DIS SLSCI NIS
e1e2i        1-207-0       none  1   1   no  B   4    off off off ---   on
ls1315       0-015-0       none  1   1   no  A   1    off off off ---   off
ls1317       0-017-0       none  1   1   no  A   1    off off off ---   on
e1m2s1       1-011-1       none  1   1   no  A   7    off off off ---   off
e1m2s2       1-011-2       none  1   1   no  A   7    off off off ---   off

Link set table is (11 of 1024) 1% full.

Note:

If there are no C linksets (linksets with the value C in the LST column) shown in the rtrv-ls output in step 2, skip step 3 and go to step 4.

Change the tfatcabmlq parameter value for one of the C linksets shown in step 2 to 0 using the chg-ls command. For this example, enter this command.
chg-ls:lsn=ls05:tfatcabmlq=0

When this command has successfully completed, this message should appear.
```
rlghncxa03w 06-10-07  08:38:45 GMT  EAGLE5 36.0.0
Link set table is ( 11 of 1024)  1% full
CHG-LS:  MASP A - COMPLTD
```
After the chg-ls command has been performed, repeat step 3 with the name of another C linkset shown in step 2.
When all the C linksets have been changed, go to step 4.

Note:
When the tfatcabmlq parameter is set to 0, its value in the rtrv-ls:lsn=<linkset name> output is shown as 1/2 of the number of signaling links contained in the linkset.
Change the value of the lsrestrict parameter.

If the current value of the lsrestrict parameter is off, enter this command.
chg-ss7opts:lsrestrict=on

If the current value of the lsrestrict parameter is on, enter this command.

chg-ss7opts:lsrestrict=off

When this command has successfully completed, this message should appear.
```
rlghncxa03w 06-10-07 00:22:57 GMT  EAGLE5 36.0.0
CHG-SS7OPTS: MASP A - COMPLTD
```
Caution:
Turning the lsrestrict option on changes the way the EAGLE routes messages by using the state of the route along with the cost of the route to determine the preferred route to use. With this option on, the preferred route is not the absolute lowest cost available route in the routeset. A route is considered available if its status is either Allowed or Restricted. If the state of the absolute lowest cost route in the routeset is Restricted, the preferred route is the lowest cost route in the routeset whose status is Allowed. Make sure that you wish to have the EAGLE route messages in this manner before turning the lsrestrict option on.
Verify the changes using the rtrv-ss7opts command. This is an example of the possible output.
```
rlghncxa03w 06-10-17 16:02:05 GMT  EAGLE5 36.0.0

SS7 OPTIONS
-----------------------
LSRESTRICT          on
```
Note:
The rtrv-ss7opts command output contains other fields that are not used by this procedure. If you wish to see all the fields displayed by the rtrv-ss7opts command, see the rtrv-ss7opts command description in Commands User's Guide.

Back up the new changes using the chg-db:action=backup:dest=fixed command. These messages should appear, the active Maintenance and Administration Subsystem Processor (MASP) appears first.

BACKUP (FIXED) : MASP A - Backup starts on active MASP.
BACKUP (FIXED) : MASP A - Backup on active MASP to fixed disk complete.
BACKUP (FIXED) : MASP A - Backup starts on standby MASP.
BACKUP (FIXED) : MASP A - Backup on standby MASP to fixed disk complete.

Figure 3-36 Configuring the Restricted Linkset Option

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