integrated services LAN (ISDN, 802.3) (ISLAN)
ISLAN (Integrated Services LAN) technology pursues the integration of IEEE 802 and ISDN protocols. This will enable parallel processing of data, voice and video from personalcomputers. This function should become possible without changing the current network infrastructure. Therefore, this standard provides for the use of existing transmission media. The transmission speeds vary depending on the distance to be covered: 4.096 Mbit/s up to 450 m or 20.48 Mbit/s up to 135 m.
The ISLAN service offer
Isochronous and asynchronous services are offered, as is necessary for data, voice and video. Standardization was started in the IEEE 802.9 working group in 1987 and has reached a stable state today with Draft 19, so that the first implementations are appearing on the market. The standard provides the user with a number of channels that he can use for his applications: The P, D, B and C channels.
The P channel (Packet Channel) provides the user with a MAC layer service according to IEEE 802. It is a full- duplex channel that can optionally also be used for setting up connections according to ITU Q.93x. In this case, it is referred to as the PD channel.
As with ISDN, the D channel is responsible for setting up connections according to the Q.93x protocols. It has a transmission rate of 16 or 64 kbit/s. Data transmission takes place in duplex mode and is packet-oriented. B channel: Two 64 kbit/s channels are also provided for use as voice channels( isochronous transmission).
There are several C channels for circuit switching, each of which has a transmission speed of a multiple of 64 kbit/s: C1 has a transmission rate of 64 kbit/s and thus corresponds to the ISDN B channel. C6 has a transmission rate of 384 kbit/s, C24 of 1,536 kbit/s and C30 of 1,920 kbit/s.
The configuration of ISLAN
In ISLAN technology, the terminals are coupled to the various networks via access units. These access units have to ensure that the respective channel is served with the appropriate quality of service.
To make these configurations possible, a three-part protocol structure is proposed in IEEE 802.9. The P channel represents the direct access to the IEEE 802.1 layer. The D channel handles the Link Access Procedure D/LAPD as known from ISDN. The activities of the IEEE 802.9 working group and thus of ISLAN were discontinued, and the standard was withdrawn.