ÀÒÌ Network Application in St. Petersburg

PeterStar, one of the largest telecommunications companies in the Northwest Region, has been offering its communication services on the St. Petersburg market since 1992.

ZAO PeterStar’s shareholders are the holding Telecominvest and the financial corporation PLD Telecom Inc. Main reasons and aims of establishing PeterStar in 1992 consisted in necessity to render up-to-date telecommunication services at the then existing worldwide level, as well as actively participating, and assisting Petersburg Telephone Network (PTN), in modernization of the communication infrastructure of the city. The company was practically founded as a subsidiary of Petersburg Telephone Network, and is still used as an area for testing new technologies and equipment under Russian conditions. PTN applies the company’s experience to the development of its network and services rendered.

PeterStar has invested over USD60 million in the development of the city communication infrastructure. The company constructed in St. Petersburg its own fiber-optics transport network with its own numbering capacity.

Over 800 km of fiber cable is installed within the territory of the city. Data traffic is transmitted over the STM-16 fiber transport network. The digital dedicated channel network is organized as a hierarchical system structure and consists of five rings. The structure provides for 100% redundancy due to automatic channel routing allowing an alternative data transmission rout to be selected in case of any network segment being damaged. By means of a hierarchical system of multiplexers installed at the PeterStar network nodes high-speed channels can be arranged (2 Mbps, 155 Mbps, 622 Mbps, and 2.4 Gbps at the most capacitive nodes), as well as channels with a lower data speed (19.2 Kbps – 2 Mbps).

The network coverage includes the whole territory of the city and the nearest suburbs. The network is constructed in a way allowing the PeterStar services to be available at any city site. The network is being continuously developed. As new technology appears and is implemented the network is updated: new nodes are put into operation, the capacity of the existing nodes increases.

The company’s transport network is built on the SDH digital transmission systems of the STM-16 level (2.4 Gbps) and STM-4 level (622 Mbps) made by Lucent Technologies (USA) and ECI Telecom (Israel); on the PDH copper-cable transmission systems made by Lucent and ADC (USA); multiplexers and transmission system equipment from General DataComm and Newbridge providing data transmission.

Several overlay networks exist within this transport network. Two basic networks are the telephone network and data network. The telephone network is controlled by the 5ESS switches manufactured by Lucent Technologies and consists of the telephone network itself and the ISDN network as a superstructure built over the telephone network. LT switching equipment provides service for over 10,000 customers.

The data network combines the dedicated channel network, the Frame Relay network and the ATM network. And the FR is for the most part an ATM subnetwork.

At the customer level subscriber access to the dedicated digital channel services is provided via digital subscriber terminals arranged over copper or fiber cable. Depending on the channel capacity selected different transmission system equipment is installed at the subscriber’s. The user interface connector is considered the dedicated channel termination.

ÀÒÌ NETWORK CONSTRUCTION

In 1997, based on the analysis of traffic growth on the Frame Relay network and forecasts for its further growth a conclusion was made on necessity of expanding network resources, for the resources of the then existing network would have been exhausted by the end of 1998. As the demand for service grew, a higher information capacity of the network required on the trunks of the network itself, as well as on the interfaces with major information sources such as open trade systems. Having calculated the rate of FR network load growth, the technical department of the company’s planning group came to the conclusion on the expediency of switching the entire RF network stream over to a more powerful backbone base.

SELECTING DATA NETWORK STRUCTURE

Having analyzed functional and pricing characteristics of packet switching equipment the company’s employees revealed that based on the requirement for scalability, expandability, control and cost optimization it would be most reasonably to choose a multilevel network structure with separate access at low and high speeds. The structure should allow the company to fully support those solutions on subscriber access organization having been used at that time.

To implement that network structure two options were suggested. The first solution consisted in arranging internode connections using PDH (SDH) dedicated channels.
The second solution covered the organization of data switching nodes based on ÀÒÌ equipment.

Advantages of the second approach:

• Further network expansion is carried out by just adding nodes and connections, requiring no network reconfiguration;
• Smaller number of control levels, hence a higher network stability;
• Higher network reliability due to developing transport not dependent on the dedicated channel network. Channels can be mutually duplicated;
• Provision of subscribers with expanded services (integrated transmission of video and audio information, data, Ethernet – Ethernet communication);
• Lower cost of routing one kilobit of information;
• Lower expenditure for equipment required to implement the second solution.

CHOOSING NETWORK TOPOLOGY

Network topology was selected considering the necessity of settling the following problems:

• Organization of a reliable main backbone for protocol (Frame Relay) routing;
• Isolation of the existing information streams;
• Transit trunk optimization of backbone multiplexers;
• Service provision for highly probable subscribers.

On the principle that the network must retain serviceability in case of failures not less than three switched combined into a ring should be installed on the network main backbone. Having combined the three switches into a ring at the STM-1 level, the main network’s total information capacity made 456,000 Kbps. Calculations revealed that to meet the requirement of ATM switch reachability in each STM-4 ring it would be necessary to install at least 5 equipment units. The requirement of expanded service provision was met only in case of the subscriber access point being reachable from the network’s main backbone. Considering the time period required for node deploying at a new exchange, due to the ATM switches it would be made possible to arrange access by installing on the network not more than one extra switch. Based on the above requirements six city exchanges were chosen the ATM switches to be installed on, with this allowing the required topology implementation.

NETWORK CONSTRUCTION

At the first stage it was necessary to ensure availability of the main backbone ring and the minimally required number of Frame Relay access equipment. Further development of the main backbone depended on the actual demand for the services and its territorial location.

The entire data network is built on the equipment manufactured by the American company General DataComm, therefore switches of the same company were selected as ATM equipment. Having tested this equipment during half a year PeterStar’s engineers liked it. It’s worth mentioning that equipment of other companies was tested, such as Cisco and Newbridge (a Newbridge make switch is also used on the network constructed by the company).

With almost the same capabilities of one-class switches from different manufacturers the vendor’s financial policy was determinative for choosing certain equipment.

All the above factors in the aggregate resulted in the General DataCom proposal appeared to be the most efficient for the company.

The PeterStar ATM network is built on efficient switches of the APEX NPX family manufactured by General DataComm, connected by fiber-optics trunks. The company purchased the first ATM switch made by General DataComm in the summer of 1995. As of today the network comprises 12 ATM switches (initially there were installed 4 switches).

The switches are interconnected using fiber-optics cable independently of the rest of the transport network. The network depends on neither the company’s telephone network nor the data network (the dedicated channel network).

The ATM network is the main backbone of the PeterStar data network and represents a two-level system, which upper level (base) is ATM switches, and the second level - Frame Relay switches of General DataComm. At present there are 16 of them in place.

Most data services rendered by the company use the ATM network as a high-speed core.

In the beginning of 1997 PeterStar launched the provision of Frame Relay services based on the data network constructed. Permit was obtained from Gossvayznadzor (State Communications Supervision Committee) for commercial operation of the data and telematics services network with the Frame Relay network playing the main role. Digital dedicated channels and Frame Relay network services allow branched corporate networks to be created for subscribers and access to worldwide information resources to be provided.

Based on this network a wider range of services is provided at present:

• The ATM network is used as Backbone for the FR network (main part of FR traffic passes through the ATM network, with this allowing the FR network bottlenecks to be off-loaded);
• Gateways to large information resources are built based on the ATM network. The first interface point was the Russian trading system – one of information systems having been the most popular by the time of constructing the information systems network. We are also interfaced over the ATM network with the WebPlus company - the largest Internet service provider in St. Petersburg. An ATM gateway is used to connect customers to the Internet on a permanent basis;
• Provision of ATM “point-to-point” communication;
• Interconnection of local area networks Ethernet – Ethernet.

Unfortunately, within the scope of city projects there are a small number of customers requiring at present a data rate of 10 Mbps in case of the “point-to-point” connection.

The most practicable application of ATM technology under city conditions is to provide ATM gateways to large information providers.