NTA functions; IP switching structure

Functions and duties of NTA

The Nepal Telecommunications Authority (NTA), set up under the Telecommunications Act, 2053 (1997), has these main functions and duties:

1. Issue, renew and regulate licences for telecom services.
2. Allocate and monitor radio frequencies.
3. Approve tariffs and regulate interconnection between operators.
4. Ensure fair competition and prevent monopoly.
5. Prepare and manage the national numbering plan.
6. Set and monitor quality of service standards.
7. Protect consumer interests and settle disputes.
8. Manage the Rural Telecommunication Development Fund to extend services to rural areas.
9. Type approval of equipment and adoption of standards.
10. Advise the Government on telecom policy.

IP switching

IP switching combines fast Layer-2 (ATM or label) switching with Layer-3 IP routing. In plain IP routing every packet is examined and routed hop by hop in software, which is slow. In IP switching the switch identifies a flow (a long sequence of packets between the same source and destination). The first few packets are routed normally; then a label/VC is assigned to the flow and later packets are switched in hardware without full IP lookup. Ipsilon's IP switching used this idea, and it was later developed into MPLS.

IP switch structure

        +-----------------------------+
        |  IP switch controller       |
        |  (IP routing software,      |
        |   flow classifier, IFMP,    |
        |   routing protocols)        |
        +--------------+--------------+
                       | GSMP (control)
        +--------------+--------------+
 in --->|   ATM / label switching     |---> out
 in --->|   hardware (fabric)         |---> out
        +-----------------------------+

• Switching hardware: an ATM switch fabric (or label switch) that forwards cells at high speed.
• IP switch controller: a router-like processor running IP routing protocols (OSPF, BGP) and flow classification.
• GSMP (General Switch Management Protocol): the controller uses it to set up and release connections in the fabric.
• IFMP (Ipsilon Flow Management Protocol): tells neighbouring switches to attach a label/VC to a flow.

Operation

1. Packets arrive on a default channel and are routed by the controller.
2. The controller classifies traffic; short flows (DNS, single packets) continue to be routed.
3. For a long flow, it asks the upstream node (IFMP) to send that flow on a new VC/label.
4. A connection is set across the fabric (GSMP), and later packets are switched at hardware speed.
5. Idle flows are timed out and their labels released.

Advantages: high throughput, lower delay, QoS support, and scalability; this idea led to MPLS used in today's ISP backbones.