ITU National Duplicate Point Codes

Note:

This feature applies only to 14-bit ITU national spare and non-spare point codes.

This feature allows an EAGLE mated pair to route traffic for two or more countries that may have overlapping point code values. For example, in the network shown in Figure 2-3, both Country 1 and Country 2 have SSPs with a PC value of 2047.

Figure 2-3 Network Example #1

Group Codes

Users must divide their ITU-National destinations into groups. These groups will likely be based on Country. However, one group could have multiple countries within it, or a single country could be divided into multiple groups. The requirements for these groups are:

• No duplicate point codes are allowed within a group.
• ITU-National traffic from a group must be destined for a PC within the same group.
• The user must assign a unique two-letter group code to each group.

For example, in the network shown in Figure 2-4, Country 1 can only have 1 point code with a value of 2047. Traffic coming from SSP 2047 in Country 1 can only be destined to other nodes within Country 1. In this example, the user assigns a group code of 1 to Country 1, and a group code of 2 to Country 2.

When the user enters an ITU-National point code, they must also enter the group code, using the format “point code - group code”. This group code must be used for any command that uses an ITU-N point code.

For example, to provision the EAGLE for the network shown in Figure 2-4, the user would enter these commands:

ent-dstn:dpcn=2047-aa

ent-dstn:dpcn=2048-aa

ent-dstn:dpcn=2047-ab

ent-dstn:dpcn=2049-ab

ent-ls:lsn=LS1:apcn=2047-aa

ent-ls:lsn=LS2:apcn=2047-ab

ent-ls:lsn=LS3:apcn=2048-aa

ent-ls:lsn=LS4:apcn=2049-ab

Group Code aa

The following special rules apply to group code aa:

• ITU-N MSUs received on an ITU-I linkset are assigned group code of aa.
• ITU-N destinations entered before this feature is turned on are assigned group code of aa when the ITUDUPPC feature bit is turned on.

Normal Operation

When an ITU-N message arrives at the EAGLE, the EAGLE creates an internal point code based on the 14 bit PC in the message, and the group code assigned to the incoming linkset.

For example, when a message arrives on LS3 with DPC of 2047, the EAGLE maps that to an internal point code of 2047-aa, because LS3 has a group code of aa. The EAGLE then routes the message to LS1, which is the route for 2047-aa.

When a message arrives on LS4 with DPC of 2047, the EAGLE maps that to an internal point code of 2047-ab, because LS4 uses group code ab. The EAGLE then routes the message to LS2, which is the route for 2047-ab.

C Linksets

For each group defined, a separate C-linkset must be defined. This C-linkset is used as the alternate route for point codes in the group.

For example, in Figure 2-4, LSC1 is used for point codes in Group fr. Its adjacent point code is 6201-fr, and is used as the alternate route for 6217-fr, 6218-fr, and 6223-fr.

LSC2 is used for point codes in Group ge. Its adjacent point code is group 4169-ge, and is used as the alternate route for 6200-ge, 6209-ge, and 6217-ge.

Figure 2-4 Network Example #2

For example, to provision the EAGLE for the network shown in Figure 2-5, the user would enter these commands:

ent-dstn:dpcn=6201-fr (Mate's true PC)

ent-dstn:dpcn=4169-ge (Mate's secondary PC)

ent-dstn:dpcn=6217-fr (Group fr destinations)

ent-dstn:dpcn=6218-fr

ent-dstn:dpcn=6223-fr

ent-dstn:dpcn=6200-ge (Group ge destinations)

ent-dstn:dpcn=6217-ge

ent-dstn:dpcn=6209-ge

ent-ls:lsn=LSC1:apcn=6201-fr:lst=C (C linkset used by Group fr)

ent-ls:lsn=LSC2:apcn=4169-ge:lst=C (C linkset used by Group ge)

ent-ls:lsn=LSB1:apcn=6217-fr:lst=B

ent-ls:lsn=LSB2:apcn=6200-ge:lst=B

ent-rte:dpcn=6217-fr:lsn=LSB1:rc=10 (primary route for a Group fr destination)

ent-rte:dpcn=6217-fr:lsn=LSC1:rc=20 (alternate route for a Group fr destination)

ent-rte:dpcn=6217-ge:lsn=LSB2:rc=10 (primary route for a Group ge destination)

ent-rte:dpcn=6217-ge:lsn=LSC2:rc=20 (alternate route for a Group ge destination)

Receiving an ITU-National MSU on an ITU-International Linkset

It is possible for the EAGLE to receive ITU-National MSUs on an ITU-International linkset. A linkset is considered an ITU-International linkset if it's adjacent point code is an ITU-International PC. An MSU is ITU-National if it is received on an ITU linkset (National or International), and the NIC field in the SIO is set to 2 (National).

ITU-International linksets do not have a group code. ITU-National MSUs received on ITU-International linksets will be assigned a group code of aa.

Existing ITU National Destinations

Any ITU-National destinations that were entered before Release 26.05 or before the ITU National Duplicate Point Codes feature was turned on will be assigned the group code of aa.

Interaction with Other Features

Gateway Screening

For example, in the network in Figure 2-4, if the user wanted to screen out MSU coming from 6217 in Group ge, but allow MSUs coming from 6217 in Group fr, he or she could assign different screensets to LSB1 and LSB2. The screenset assigned to LSB1 would allow MSUs from OPC 6217. The screenset assigned to LSB2 would block MSUs from OPC 6217.

Multiple Point Codes

The Multiple Point Codes feature (see “Multiple Point Code Support”) must be on in order to turn on the ITU National Duplicate Point Codes feature. For every group that is used, the user must provision either a True PC or Secondary Point Code, using the chg-sid command.

For example, in the network in Figure 2-4, two groups are used having group codes of fr and ge. An ITU-National True Point Code is entered for group fr, and an ITU-National Secondary Point code is entered for group ge.

Conversion between ITU-N and ITU-I or ANSI

Each ITU-N destination and group code can have its own ITU-I or ANSI alias PC. Each ITU-I or ANSI node can be assigned one ITU-N destination. For conversion from ITU-I or ANSI to ITU-N to succeed, the ITU-N alias of the sending node must have the same group code as the destination's group code. So each ITU-I or ANSI node can only send and receive messages from one ITU-N group.

Figure 2-5 Network for Conversion

In Figure 2-5, SSP-N1 (2045-bd) is assigned ITU-I alias 1-6-1, and SSP-N2 (2045-xy) is assigned ITU-I alias 1-7-1. SSP-I1 is assigned ITU-N alias 2130-bd and SSP-I2 is assigned ITU-N alias 2131-xy. In this example, SSP-I1 can exchange traffic with nodes in group bd, but not nodes in group xy. SSP-I2 can exchange traffic with nodes in group xy, but not nodes in group bd.

SSP-I1 (1-5-1) can send to SSP-N1 by using the ITU-I alias 1-6-1, But if SSP-I1 tries to send to 2045-xy by using the ITU-I alias 1-7-1, conversion will fail, and the EAGLE will generate UIM 1091 (Indicating OPC conversion failed).

SSP-N1 can send traffic to SSP-I1, but SSP-N2 cannot send traffic to SSP-I1. SSP-N1 sends an ITU-N MSU with DPC set to 2130. The EAGLE assigns a group code of bd to the MSU based on the incoming linkset. The EAGLE then looks up 2130-bd, determines that this is an alias for ITU-I 1-5-1, and routes the MSU to SSP-I1.

If SSP-N2 sends an ITU-N MSU with DPC set to 2130, the EAGLE assigns a group code of xy to the MSU based on the incoming linkset. The EAGLE then looks up 2130-xy, does not find a match, and discards the MSU.

To provision the SSP-N1, SSP-N2, SSP-I1, and SSP-I2 in the network shown in Figure 2-5, the following commands are used:

ent-dstn:dpcn=2045-bd:aliasi=1-6-1

ent-dstn:dpcn=2045-xy:aliasi=1-7-1

ent-dstn:dpci=1-5-1:aliasn=2130-bd

ent-dstn:dpci=1-5-2:aliasn=2131-xy

ent-rte:dpcn=2045-bd:lsn=LSB1:rc=10

ent-rte:dpcn=2045-xy:lsn=LSB2:rc=10

ent-rte:dpci=1-5-1:lsn=LSB3:rc=10

ent-rte:dpci=1-5-2:lsn=LSB3:rc=10

Limitations

The ITU National Duplicate Point Code feature has the following limitations:

• Duplicate Point Codes are only supported for ITU-National Destinations.
• ITU-National traffic from a group must be destined for a PC within the same group.
• No duplicate point codes are allowed within a group.
• For each group that is provisioned, a separate ITU-N C-linkset must be provisioned.
• It is not possible to change a destination's group code. If the user wants to move a destination from one group to another, the user must provision a new destination that uses the new group code and delete the old destination.
• If conversion between ITU-N and ITU-I or ANSI is used, only 1 ITU-N group can send traffic to a specific ANSI or ITU-I node.