DB2 digital branching in networks of small capacity
DB2 digital 2 Mbit/s branching equipment Digital branching equipment the DB2 is a member of the Nokia Dynanet family of access network products. The DB2 performs the functions of branching equipment that can be controlled dynamically, using the Dynanet channel unit selection. Applications The DB2 equipment family offers a wide range of different branching and drop/insert functions. Typically, the DB2 is used in private chain, tree or ringshaped networks. In these applications a small number of channels are used at inter-mediate stations, where different channel types are often needed. The 2 Mbit/s or individual channels must be protected when availability is a strong requirement. In applications where dynamic network structure is the
optimum solution, the DB2 is the key component. In public networks, dynamic branching can be used to establish semi-permanent or leased speech and data lines. The DB2 is also wellsuited for data network applications, and for arranging line signal and individual channel protection. Channels from small exchanges, concentrators and remote subscriber stages can be collected to one 2 Mbit/s stream to save radio frequencies, line equipment, and exchange interface lines.
Digital branching principles
Various functional alternatives
The DB2 branching equipment forms a 2 Mbit/s bi-directional branch to the main line signal. The branch and the main line signal have the same speed and frame structure. Individual channels are connected through or branched and the operation is completely digital. Thanks to the digital cross-connect matrix, very flexible timeslot rearrangements are possible. The channel-associated signalling is branched together with the corresponding channels. Dropping and inserting is achieved by plugging in VF or data interface units to the DB2 equipment. The Dynanet interface units have access to all timeslots of the signals passing through.
The DB2 branching equipment consists of two plug-in units for branching and a wide range of VF and data interface units for dropping and inserting individual channels. Programming and combining the units in various ways offers an almost unlimited number of different functional alternatives.
Digital branching Dynamic branching makes it possible to change branching configurations during normal operations. This unique feature makes it possible to fully and flexibly use the transmission network capacity. The various branching alternatives are stored in each DB2 in the network. The network reconfiguration can be done manually through the service interface or it can be triggered automatically, based on e.g. alarms or the time of day. Changes in branching configurations do not disturb traffic on those channels that remain unchanged.
The four main DB2 configurations are: • DB2B, basic branching equipment • DB2P, protected branching equipment • DB2T, terminal (change-over) equipment • DB2B-LP loop-protected branching equipment The protected branching equipment, DB2P, has duplicated interfaces for the line signals from both directions. The built-in logic automatically selects the better 2Mbit/s input signals to be branched. It is therefore possible to use the DB2P when 2Mbit/s signals need to be protected by using two alternative paths to the branching point. Likewise, the DB2T can be used as a protective hitless switch at the end of a protected branching chain. The DB2T selects the faultless signal in the receive direction and duplicates the signal in the transmit direction. In ringshaped networks, the DB2B-LP protects the individual channels (nx32/64k) and the synchronisation.
Flexible installation The Dynanet installation concept offers flexible installation options in wallmounting cases (4-and 8-slot subracks) and 19”racks. The units can be placed freely in any vacant unit space, also of other applicable Dynanet units, so flexibility of the configuration can be increased.
Channel units Dynanet channel units can be connected to all DB2 configurations. The VF and data interface units are connected directly to the internal 2 Mbit/s bus of the equipment. Each unit and channel can be programmed for any time-slot. The DB2, the DM2 multiplex equipment and the DN2 cross-connect equipment all use the same Dynanet channel units, described in separate brochures.
Common channels The DB2 supports both VF and digital common channels. The VF-type common channel is based on the summing of PCMcoded signals, typically used for: • polling data connections • base station systems for mobile phones • service telephone systems
Integrated maintenance and versatile programming The DB2, like all Nokia transmission equipment, has an intelligent service interface for maintenance operations and configuring equipment. Locally, the service interface is accessed either with the handheld Nokia Service Terminal or with a PC which is equipped with the Macro Service Terminal Emulator (MSTE) or the DB2 Manager program. The DB2 service interface offers: • programming of branching configurations • programming of operational modeand settings • detailed alarm monitoring • test point and alarm output programming • signal quality measurements • supervision and control of channel units Centralised network management is offered by the Nokia NMS network management system.
The digital common channel is based on bit-by-bit summing, used in digital multipoint data connections, where Dynanet data interface units are used, for example.
VF of Data
DM2 VF of Data
Technical data Product codes 24001 24002 24010 24011 24060.04 24060.05 24060.1 24060.2 24060.3 24060 24061.04 24061.05 24061.1 24061.2 24061.3 24061
Branching Unit, B2 2x2 Mb/s 75/120 ohm Branching Unit, B2 2x2 Mb/s 75 ohm 2 Mb/s Switching Unit, X2 75/120 ohm 2 Mb/s Switching Unit, X2 75 ohm PROGRAM FOR B2-UNIT, DB 2B-BP/ENG PROGRAM FOR B2-UNIT, DB 2B-CD/ENG Program for B2-unit /DB 2B-LP/E Program for B2-unit /DB2 T/E Program for B2-unit /DB2 P/E Program for B2-unit /DB2 B/E PROGRAM FOR X2-UNIT, DB 2B-BP/ENG PROGRAM FOR X2-UNIT, DB 2B-CD/ENG Program for X2-unit /DB2 B-LP/E Program for X2-unit /DB2 T/E Program for X2-unit /DB2 P/E Program for X2-unit /DB2 B/E
ITU-T Recommendations Bit rate Bits per time-slot Time-slots per frame Time-slots for VF and Data Frames per multiframe Multiplexing
G.703, G.704, G.706, G.732, G.823, G.821 2048 kbit/s 8 32 30 (31 without CAS) 16 Synchronous 32 kbit/s time-slot interchanging
Branched time-slots VF (PCM) omnibus channels Digital omnibus channels Bit rate of each branched channel Control of branching
0-30 (31) time-slots 0-30 (31) time-slots 0-30 (31) time-slots 32...1920 kbit/s (n x 32 kbit/s) via the service interface
ITU-T Recommendations Bit rate Code Pulse shape Peak voltage/impedance Peak voltage tolerance Input signal attenuation VF and data Number of VF and Data units Other interfaces Service interface Auxiliary data channel
G.703, G.823 2048 kbit/s ±50 ppm HDB3 rectangular 3V/120 ohm, 2.37V/75 ohm 10% 0 to 6 dB/1 MHz Interface units of the Dynanet family are detailed in separate leaflets Limited by subrack space only
Central battery voltage Power consumption without channel units
20...72 VDC DB 2B DB 2P 5W 10 W
NDM 19” subrack (16 plug-in units) NDM 8-slot subrack (7 plug-in units) NDM 4-slot subrack (4 plug-in-units)
297 mm 297 mm 322 mm
Operation Electromagnetic compatibility (EMC)
ETS 300 019, Class 3.1E ETS 300 086 (2000)
75-9600 bit/s, V.11 ITU-T 600-2400 bit/s, V.11 ITU-T
Copyright © 2007 Nokia Siemens Networks. All rights reserved. SURPASS is a trademark or a registered trademark of Nokia Siemens Networks. Other company and product names mentioned herein may be trademarks or trade names of their respective owners.
DB 2T 5W
450 mm 225 mm 112 mm
DB 2B-LP 5W
Depth 222 mm 214 mm 218 mm