C H A P T E R 1 I N T R O D U C I N G T H E V 1 0 0
V100 Versatile Multiplexer Technical Manual Version 2.2
Page 12 of 231
1.2.8
TDM Link Card
A TDM Link card may be fitted in the Special Option slot to provide an additional aggregate interface port.
This port allows tributary data channels to be selected as Time-Division Multiplexed (TDM) ports, which
are then carried over the new aggregate, not in a packetised manner but over fixed timeslots. The benefit
of this feature is that such data does not then suffer the error-extension phenomenon associated with all
packetised protocols, where a single bit error affecting a packet causes the whole packet to be rejected.
When a TDM Link card is fitted, the network must provide the master clock and the bit rate is restricted to
512Kbps
1.2.9
Expansion – The High Speed Channel
The V100 has a unique High-Speed serial Channel (HSC) dedicated to the interconnection of units. This
port allows data and control information to pass between two chassis, so as to form a concatenated unit.
Such a combination can then operate as one cohesive unit, a feature which not only gives expansion
capability but also allows units to be decommissioned and replaced without disruption.
A 9-way D-type connector presents the 4-wire RS485 serial bus, which runs a proprietary protocol at
4Mbps. This allows up to 2Mbps of full-duplex data to pass between linked units and also carries receive
and transmit clock signals to all units. In this way, any data port on either unit may be used as an
aggregate WAN port and the demultiplexed data routed to a tributary channel on either chassis via the
HSC. Full flexibility of clock sourcing via the HSC permits the network clock to be onward-linked to any
other unit.
1.2.10
10/100base-T Integrated Router
Revision D of the V100 chassis introduces the integrated IP Router, presented on an RJ45 connector on
the front panel. The majority of applications now demand IP connectivity in the field, as well as the
established voice and data facilities. The V100 presents an integrated 10/100base-T port capable of
supporting IPV4 bridging and routing functions over a satellite link. IP traffic is carried over the proprietary
V100 link structure alongside other media. This confers a number of benefits such as improved
fragmentation, efficiency and low latency.
The V100 IP port offers bridging and static routing capability with DHCP Server/Relay functions built in. A
UDP relay function enhances this by allowing communication between a remote client and a server on the
home network. Users can now plug their laptop into the remote V100 and log in to their home network,
surf the internet and pick up E-mail.
The V100 IP port may also be used to provide IP aggregate connectivity between V100s over an
intermediate IP network thus enabling data and voice to be carried over IP. The technology is not Voice
over IP but Voice and IP.