Flexible Intermediate GTT Load Sharing

Flexible Intermediate GTT Load Sharing provides more flexible GTT load sharing arrangements for GTT traffic requiring intermediate global title translation (the routing indicator in the message is GT) than the load sharing arrangements provided by the Intermediate GTT Load Sharing feature. For the EAGLE to perform Flexible Intermediate GTT Load Sharing, the Flexible GTT Load Sharing and Intermediate GTT Load Sharing features must be enabled and turned on.

Intermediate Load Sharing Feature Only

With the Intermediate GTT Load Sharing feature enabled and turned on and the Flexible GTT Load Sharing feature not enabled, the EAGLE load shares post-GTT destinations when intermediate global title translation is being performed through the use of the MRN table. The destination point codes in the MRN table can appear in the MRN table only once. The MRN table contains groups of point codes with a maximum of 100 point codes in each group. This arrangement allows only one set of relationships to be defined between a given point code and any other point codes in the MRN group. All global title addresses in the GTT table that translate to a point code in the given MRN group will have the same set of load sharing rules applied.

For example, the following point codes and relative cost values are provisioned in the MRN table.

PC             RC
   005-005-005    10
   006-001-001    10
   006-001-002    10
   006-001-003    10
   006-001-004    10
   006-001-005    10
   006-001-006    10
   006-001-007    10

When the point code in the intermediate global title translation is translated to 005-005-005, all traffic routed using the global title addresses in the global title translations containing this point code are load shared equally, no matter what the global title address is.

Addition of Flexible GTT Load Sharing Feature

When the Intermediate GTT Load Sharing and the Flexible GTT Load Sharing features are enabled and turned on (thus allowing Flexible Intermediate GTT Load Sharing to be performed), the intermediate GTT load sharing arrangements are determined by the following:

• The MRN set assigned to the global title translation
• The translated point code in the message assigned to the global title translation
• The global title address in the message assigned to the global title translation

When a global title address in a global title translation is translated to a point code, the MRN set assigned to the global title translation and containing the translated point code determines how load sharing is applied to the traffic for this global title translation.

An MRN set is a group of point codes in the MRN table defining the GTT load sharing rules that are applied to a global title translation. The method of load sharing is determined by the relative cost (RC) value assigned to each point code in the MRN set. There are three types of load sharing that can be performed:

• Dominant
• Load shared
• Combined dominant/load shared

Dominant

All the point codes in a dominant MRN set have different relative cost values. The translated point code in the message is the preferred point code that the message is routed on. The relative cost value assigned to the preferred point code does not have to be the lowest value in the MRN set. All traffic is routed to the preferred point code, if it is available. If the preferred point code becomes unavailable, the traffic is routed to next alternate point code. When the preferred point code becomes available again, the traffic is then routed back to the preferred point code.

The following shows sample output from the rtrv-mrn command for a dominant map set.

MRNSET      PC             RC
DFLT        225-200-167    10
            225-200-163    20
            225-200-165    30
            225-200-164    40
            225-200-160    50

For example, if the preferred point code is 225-200-164 (relative cost 40) and it becomes unavailable, the traffic is routed to 225-200-160 (relative cost 50). If that point code is unavailable, the next point code that is attempted is at the top of the list, 225-200-167 (relative cost 10).

Load shared

All the point codes in a load shared MRN set have the same relative cost value. Traffic is shared equally between the point codes in this type of MRN set.

The following shows sample output from the rtrv-mrn command for a load shared map set.

MRNSET      PCN            RC
DFLT        15608          10
            15728          10
            15720          10
            15712          10
            15704          10
            15696          10
            15688          10
            15680          10
            15672          10
            15664          10
            15656          10
            15648          10
            15640          10
            15632          10
            15624          10
            15616          10

Combined dominant/load shared

A combined dominant/load shared MRN set is a combination of the dominant and load sharing MRN sets. At least two of the point codes in the MRN set have the same relative cost value, and at least one other point code has a different relative cost. The traffic is shared equally among the point codes with the same relative cost values. If the point codes with the same relative cost as the preferred point code all become unavailable, the traffic is routed to the next set of point codes in the MRN set and shared equally between them.

The following shows sample output from the rtrv-mrn command for a combined dominant/load shared map set.

MRNSET      PC             RC
DFLT        225-200-175    10
            225-200-174    20
            225-200-171    20
            225-200-173    30
            225-200-170    30
            225-200-172    40
            225-200-169    40
            225-200-168    50

In this example, if the preferred point code is 225-200-173, the traffic is shared between the two point codes with a relative cost of 30. If those become unavailable, the traffic is routed to the point codes with a relative cost of 40. If those become unavailable, the traffic gets routed to the point code with a relative cost of 50. If that point code becomes unavailable, the traffic is routed back of the top of the list to the primary point code that has a relative cost of 10.

Point Code Assigned to Multiple MRN Sets

With the Flexible GTT Load Sharing feature enabled, the same point code can be assigned to multiple MRN sets. The relative cost value of this point code in each MRN set can be different.

In the following example, the point code 002-002-002 is assigned to three MRN sets.

MRNSET      PC             RC
1           225-200-999     5
            002-002-002    10
            225-200-174    20
            225-200-171    30
            225-200-173    40

MRNSET      PC             RC
2           225-200-173    20
            225-200-174    20
            225-200-171    20
            002-002-002    20
            225-200-170    20
            225-200-172    20
            225-200-169    20
            225-200-168    20

MRNSET      PC             RC
3           004-004-004    20
            225-200-174    20
            225-200-170    30
            002-002-002    30
            225-200-172    30
            225-200-169    40
            225-200-168    40

In MRN set 1, point code 002-002-002 is in a dominant MRN set and has a relative cost value of 10. In MRN set 2, point code 002-002-002 is one of eight point codes in a load shared MRN set, each with a relative cost value of 20. In MRN set 3, point code 002-002-002 is assigned the relative cost value of 30 in a combined dominant/load shared MRN set whose primary (first) point code is 004-004-004 with a relative cost value of 20.

MRN set 1 is assigned to a global title translation containing the global title address of 9195551212. When the point code in this intermediate global title translation is translated to 002-002-002, point code 002-002-002 handles all the traffic for this intermediate global title translation until this point code becomes unavailable. When point code 002-002-002 becomes unavailable, the next point code (225-200-174) in this dominant MRN set handles the traffic until this point code becomes unavailable, or until point code 002-002-002 becomes available again.

MRN set 2 is assigned to a global title translation containing the global title address of 8285551212. When the point code in this intermediate global title translation is translated to 002-002-002, the traffic for this intermediate global title translation is shared equally among all members of the MRN set.

MRN set 3 is assigned to a global title translation containing the global title address of 3365551212. When the point code in this intermediate global title translation is translated to 002-002-002, the traffic for this intermediate global title translation is shared equally among all members of the MRN set with the relative cost value of 30, including 002-002-002. When all of these point codes become unavailable, the traffic is shared equally among all the point codes with the relative cost value of 40. If these point codes become unavailable, the traffic is shared equally among the point codes with the relative cost of 20.

By allowing a point code to be assigned to multiple MRN sets, and by assigning an MRN set to a specific global title address, different load sharing arrangements can be made based on the global title address of the global title translation and the translated point code.

The same MRN set can be assigned to multiple global title translations.

For the EAGLE to perform Flexible Intermediate GTT Load Sharing, the Flexible GTT Load Sharing feature must be enabled with the enable-ctrl-feat command, and turned on with the chg-ctrl-feat command. Perform the Activating the Flexible GTT Load Sharing Feature procedure to enable and turn on the Flexible GTT Load Sharing feature. The Intermediate GTT Load Sharing feature must also be enabled with the enable-ctrl-feat command, and turned on with the chg-ctrl-feat command. Perform the Activating the IGTTLS feature procedure to enable and turn on the Intermediate GTT Load Sharing feature.

The Flexible GTT Load Sharing feature can also be turned off with the chg-ctrl-feat command. If the Flexible GTT Load Sharing feature is turned off, and the Intermediate GTT Load Sharing feature enabled and turned on, provisioning for Flexible Intermediate GTT Load Sharing can be performed with the ent-mrn, dlt-mrn, chg-mrn, and rtrv-mrn commands. The EAGLE will not perform Flexible Intermediate GTT Load Sharing on GTT traffic requiring intermediate global title translation. Perform the Turning Off the Flexible GTT Load Sharing Feature procedure to turn off the Flexible GTT Load Sharing feature.