How to Set Up... International Frame Relay Services

Frame Relay is a link level data networking service that is particularly

well-suited to handling "bursty" traffic. It was designed primarily to

provide efficient LAN-to-LAN interconnection, but is also highly effective at

supporting other types of data such as SNA, and more recently, voice, video and

complete multimedia traffic.

Structurally, frame relay packets transmit data in much the same way as X.25,

but because of the widespread digital facilities and smarter end-devices, there

is no necessity for X.25 facilities such as error correction and flow control,

with the overheads that these incur. This means that frame relay technology

utilizes the robustness of today’s digital transmission media to obviate

transmission overheads, and still maintains the quality of the transmission by

relying on the smartness and intelligence of devices at the network ‘end-points’

Frame relay, by operating at Level 2 rather than Level 3, does not rely on

the wide area network to provide error correction. The intelligent CPE and

application software which use higher level protocols provide this error

correction at the end points. Consequently, the protocol requires much less

processing in the network switches and offers higher throughput rates than is

typically supportable with public X.25 services.

Step1: Frame Relay Technology

The frame relay protocol provides increased efficiency by allowing multiple

logical connections to take place over one physical access line into the

network. This provides significant savings over private lines by:

• minimizing the number of leased
  
  lines required to connect sites

• minimizing the
  
  CPE requirements

The frame relay links mentioned above are referred to as

Permanent Virtual Circuits (PVCs). Each PVC is a logically defined path through

the network that interconnects two end-points just as a private (leased) line

would, except that network bandwidth is not dedicated solely for the use of that

PVC. Bandwidth can be allocated dynamically "on demand", allowing a

user to increase its bandwidth, as needed. Because of this, it is necessary to

define a service parameter for data throughput to ensure that all users can both

take advantage of additional bandwidth when this is available, but also have a

set amount of throughput on which they can depend. This parameter is known as

the Committed Information Rate (CIR), and represents the minimum throughput

which the network will deliver on a PVC regardless of how busy the network is.

Data sent in excess of this rate is known as "excess data" or burst,

and the ability to deliver this will be determined by the overall network

traffic at the same instant.

The way a network handles excess data is as important as how

it handles committed data. If a network rejects significant proportions of

excess data, the overall performance on a PVC can be greatly reduced.

While most global service providers worldwide support traffic

burst for predefined slice of time (a few mili seconds or so), a few carriers

have designed their network to carry traffic bursts for much longer periods of

time depending on the network utilization during those times. Notable amongst

these is Global One, which has branded its committed throughput as Enhanced CIR

(E-CIR). E-CIR remains available to the user/customer for as long as the

bursting demands, depending on the network availability. The network doesn’t

automatically withdraw the burst support after pre-determined periods of time.

Step 2: Frame Relay Providers in India

It was in early 1998 that international frame relay services

were launched in India. Global One was the first international carrier to launch

international frame relay services in India. However, there are other players

besides Global One today, including Equent,Concert,TMI and C&W.

To comply with the regulatory framework, all these carriers

have partnered with VSNL to provide the services in India. All the international

frame relay service providers have commercial sharing arrangements on the port

at India end and PVC/CIR.

Step 3: Frame Relay Components

The individual components that comprise frame relay services

include the access line, the port and PVC. It is important to understand the

functionality of these components as they are the basis for implementing frame

relay service. The figure entitled "Frame Relay Components",

illustrates how these components fit into a frame relay network.

Access line: The access line is the physical connection

(leased line) between the frame relay service providers Point-of-Presence (PoP)

and the customer location. The access line speed must be equal to, or greater

than, the port speed.

Port: The port is the physical connection to a frame relay

switch. Each port is capable of supporting multiple PVCs. Proper sizing

(determining the speed) of the port is therefore, very important. In most of the

networks, each site only needs one port connection, even though many different

users, applications and protocol, may need network access.

In addition to taking into account the number of PVCs and CIR

speeds, service provider will advise customers on the speed ports that are

recommended for certain locations.

Permanent Virtual Circuit (PVC): PVC is the logical

connection between two frame relay ports. Each end of the PVC is defined by the

port address and a Data Link Connection Identifier (DLCI).

Frames are routed through the network via each PVC. The DLCI

is an address which is carried in the frame header. The DLCI identifies a

logical connection between the user and the local network access node. The DLCI

has local significance only and may change as the PVC is routed through the

network. Overall, DLCI addresses ensure that the integrity of the PVC is

maintained.

The service provider needs to assign each PVC a Committed

Information Rate (CIR). The CIR is the speed of transmission for a particular

logical connection.

Customer Premise Equipment (CPE): Frame relay service

requires that every customer location connected to the network, has two types of

equipment on its premise:

• DSU/CSUs or NTUs, channel banks
  
  and/or channel bank cards

• Routers and/or multiplexers

In India, DoT provides only leased line connectivity to the

PoP of the service provides, so the customer has to buy router and CSU/DSU from

the service providers or the local market. Mostly, VSNL provides the CSU/DSU for

international frame relay services, which has a partnership with all the

international service providers in India like Global One.

Step 4: Implementation of Frame Relay Services

Frame relay can be used for connecting the offices of an

organization for running any business.

Applications, like ERP, LAN-to-LAN connectivity for messaging

and other data transfer or for any specific customized application that an

organization is already using, which needs to talk to the mail/central server at

the HO or vice a versa.

Depending on the kind of application and the amount of data

transfer requirement, customers can decide on the CIR options like 16 K to 1 MB

and port speed up to 2 MB. For customers wanting to connect their HO to multiple

locations, they can go for a port with higher speed at HO, and then multiple PVC

between all the locations to the HO server.

Future of FR services

In future we can see a major development happening in Frame

Relay technology like:

• Higher Access Speed: Looking at
  
  the improvement in the telecom infrastructure and the fiber optic cable
  
  deployment, in future, service providers will be able to offer higher access
  
  speed of E1 and more as there will not be any last mile problem.

• Shadow PVC: Major FR services
  
  providers like Global One, have started offering shadow PVC as a part of the
  
  product for companies running mission critical business applications. In
  
  case the main PVC that you are working on is down due to international cable
  
  fault or any other reason, the Shadow PVC (an alternate PVC is defined,
  
  which is used when the main PVC is down) is used, and so, your operations
  
  are not disturbed.

• Classes of Services: Prioritize
  
  your traffic internationally based on application needs, like Priority
  
  class( High transfer priority for time-sensitive applications like SAP, SNA),
  
  LAN class ( Normal transfer priority for volume-sensitive applications like
  
  email) and Multimedia class ( highest transfer priority for real time
  
  applications, high disgard priority, CIR 8k to 384k).

• Lower Cost: As the infrastructure
  
  is getting ready for higher bandwidth requirement, the cost per unit will go
  
  down and so, the rates for Frame Relay services will also be reduced.

• Improved SLAs: With a better
  
  infrastructure, customers can expect improvement in the quality of services,
  
  like last mile, and will thus, be able to sign an improved SLA (Service
  
  Level Agreement).

• Provide end to end Solution: For
  
  customer convenience, major plays like Global One have already started
  
  offering end-to-end transport solutions (router, loop, infrastructure etc).

Kamlesh Raval

marketing manager Global One India Pvt Ltd.