TN2185B

DEFINITY Made Easy Tools
Issue 2, November 2000

DEFINITY Hardware

TN2185B

The TN2185 supports 8 4-wire ISDN BRI line S interfaces, each operating at 192 Kbps, with 2 B-channels (64 Kbps) and 1 D-channel (16 Kbps). The TN2185 interfaces to the DEFINITY LAN bus and the TDM bus to provide the TE side of the BRI interface.

The TN2185 is similar to the TN2198 except the TN2185 is a 4-wire S interface instead of a 2-wire U interface. Another difference is the function of the SCOTCH/NPE and SAKI are replaced by the network control element (NCE).

For each port, information communicates over two 64 Kbps bearer channels called B1 and B2, and over a 16 Kbps channel called the demand channel, or D channel. The D channel is used for signaling. Channels B1 and B2 can be circuit switched simultaneously, or either of them may be packet switched, but not both at once. The D channel is always packet switched. The circuit switched connections have a µ-Law or A-Law option (on a per-board basis) for voice operation and operate as 64 kbps clear channels when in the data mode. The packet switched channels support the LAPD protocol, however, the TN2185 does not terminate on LAPD protocol. The S interface does not support switching of both B channels together as a 128 Kb/s wideband channel.

The TN2185 has a long range up to 18,000 feet (5486 m) maximum from the system to the NT1 device. In a multiple terminal environment, the B channels are shared only on a per-call basis. For example, if the B2 channel is for data, then the B2 by 1 terminal excludes the others from having access to it. When a used device communicates over the D channel to access B1 or B2, that channel is owned until the call is taken down (no party on line). The D channel is always shared among the terminals. Replaces the TN-PRI/BRI PRI to BRI converter (ETSI-BRI) and the TN464F.

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