User's Manual

605-0000-595 Subscriber Terminal Installation and Commissioning
24
The specific impedance of the NTU allows tests to be performed by the SIU to detect the
presence of any attached CPE.
Packet Data
Packet Data using 10/100baseT Ethernet links
The Type 42 P1 and iST offer an Ethernet service, which allows applications such as home
Internet access and Virtual Private Networks (VPN) for business users. It is designed to
operate with downlink speeds of up to 2Mbit/s and uplink up to 1Mbit/s, although the typical
configured uplink rates will depend on the number of STs on the system.
The system uses Ethernet bridging, which has the advantage of relaying frames based on
their MAC address, and so allows higher level protocols such as TCP/IP and IPX to pass
transparently across the system. In this manner, the system is easy to configure, and
provides a link that is transparent to devices on the LAN at each end of the bridge.
The system links Ethernets using self learning MAC bridging and supports the following
features:
• Ethernet IEEE 802.3 10baseT RJ45 connector
• Transparent Bridging allows the use of TCP/IP, IPX and other protocols over the link.
• Supports up to 480 P1V2 Subscriber Terminals per RF channel
• RF packet throughput capacity up to 8.5Mbit/s downstream, 5.7 Mbit/s upstream
IEEE 802.1q VLAN s
The 802.1Q standard (VLAN tagging) is also supported by the system, which is a secure
means of segmenting a network. The traffic between VLAN's is restricted, thereby providing
secure boundaries and limiting the propagation of broadcast and multicast traffic. This means
that any equipment supporting VLAN tagging will be able to connect to the Type 42 P1 , and
present each VLAN id on a separate Ethernet segment for connection into the appropriate
network.
IEEE 802.1q VLAN support on the AS4020 and Router provides security isolation is required
between these corporate customers by creating Corporate Virtual Private Networking and
allows independent LAN traffic to be carried over a single physical interface. 802.1q VLAN
adds an identifier to each ethernet packet to identify which VLAN it belongs to.
A router supporting 802.1q provides multiple VLAN subinterfaces (and IP addresses) on a
single physical Ethernet interface. VLAN security allows independent assignment (including
duplication) of IP addresses between VLAN groups.
VLAN security is used together to provide total security isolation of grouped Ethernets.
Ethernet linking is via MAC bridging providing protocol transparency. The user interface is
10baseT on RJ45 socket.
Overview of ST operation working on AS4020
Block Data Mode
BDM is used on the radio interface and transmits blocks of data using a connectionless
protocol
BDM transfers data across the air interface in discrete sized blocks. The payload for a given
destination may be contained within a single block (size permitting), or across multiple blocks.
The data field spreading factor, modulation and coding rate may be allocated by the system
on a per block basis to match the signal to noise ratio of the channel.
In the uplink an ST is allocated up to 4 RWs for voice and up to 4RWs for packet to transmit
on by the CT on a per slot basis.
The block duration is fixed throughout the system.