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Data networks and open system communications
BY BERIT SVENDSEN AND METTE RØHNE
Introduction
The most widespread data communication service offered today
by public network operators is the X.25 packet mode service.
Frame Relay is a high speed data service (64 kbit/s–2 Mbit/s) and
is especially suited for interconnection of local area networks.
Frame Relay is a simplified data service compared to X.25 and
requires less processing in the network. Frame Relay is transferring
data transparent in layer 2 frames without functions for
sequence control, retransmission and error correction inside the
network.
In this summary the latest results in the following three organisations
are presented:
- International Telecommunication Union – Telecommunication
Standardisation Sector (ITU-T)
- European Telecommunication Standards Institute (ETSI)
- European Institute for Research and Strategic Studies in
Telecommunication (EURESCOM).
ETSI
NA 2, NA 5 and SPS 5 are the main sub technical committees
doing standardisation work on data networks and data services.
NA 2 is responsible for network standards required to introduce
a European Frame Relay service. NA 2 has also been responsi-
Table 2 Standards in the area of Frame Relay in NA2 and NA5
ID Organisation Name
ETS 300 007 ETSI NA 2 Support of packet mode terminal
equipment by an ISDN
ETS 300 099 ETSI NA 2 Specification of the Packet Handler
Access Point Interface (PHI)
Draft RFHI ETSI NA 2 Specifications of the Remote Frame
Handler Interface
ETSI/STC ETSI NA 2 Frame Relay Service – General
NA2(93)07 description
ETSI/STC ETSI NA 2 ISDN – Frame Relay Bearer Service
NA2(93)08 – Service Definition
ETSI/STC ETSI NA 2 Frame Relay Data Transmission
NA2(93)09 Service – Service Definition
Draft ETS ETSI NA 5 Support of Frame Relaying Bearer
DE/NA-53204 Service in B-ISDN and Frame Relay
interworking between B-ISDN and
other networks
Draft ETS ETSI NA5 B-ISDN - Frame Relay Bearer
DE/NA-53207 Service – Service Definition
ble for packet mode service in ISDN. NA 2 has finalised the
Packet Handler Interface (PHI) specifications and the packet
mode service in ISDN. NA2 is currently working with service
descriptions for Frame Relay service in ISDN and dedicated
Frame Relay networks. The study is also focused on a Remote
Frame Handler Interface (RFHI).
The following list of documents is the most important results:
- ETS 300 007 ‘Integrated Services Digital Network (ISDN);
Support of packet mode terminal equipment by an ISDN’
- ETS 300 099 ‘Integrated Services Digital Network (ISDN),
Specification of the Packet Handler Access Point Interface
(PHI)’
- Draft RFHI ‘Integrated Services Digital Network (ISDN)
specifications of the Remote Frame Handler Interface’.
Three different drafts on service descriptions
- ‘Frame Relay Service – General description’
- ‘ISDN Frame Relay Bearer Service – Service Definition’
- ‘Frame Relay Data Transmission Service – Service Definition’.
The plan is that NA 2 will finish the draft service definitions
and will start to work on Frame Relay Network-to-Network
Interface during 1994.
In NA 2 France Telecom, Alcatel Bell, Siemens and Swiss PTT
have taken an active part.
NA 5 is responsible for the service definition of the Frame
Relay service to be offered in B-ISDN and Frame Relay interworking.
The work is focused on the support of Frame Relay in
B-ISDN and interworking between B-ISDN and other networks.
The following documents are available as drafts:
- ‘Draft B-ISDN – Frame Relay Bearer Service – ServiceDefinition’
- ‘Draft support of Frame Relaying Bearer Service in B-ISDN
and Frame Relay interworking between B-ISDN and other
networks’.
The plan is that NA 5 will finish these drafts in 1994. Nokia,
France Telecom, Swiss PTT and Ellemtel have been the most
active contributors.
The protocols at the User-to-Network interface for Frame Relay
will be standardised by SPS 5. The standardisation will be based
on the corresponding recommendations made by ITU-T.
EURESCOM
There is still one important item of Frame Relay that is not
solved. This is the requirements for network-to-network interface
so that Frame Relay networks from different operators can
interwork. Therefore, in order to assist and enforce these studies
in Europe, Project P301 Frame Relay Network-to-Network Interface
definition was started in April 1993.