Unit installation

FCD-E1 Introduction E-1
Appendix E
IR-ETH Interface Module
E.1 Introduction
IR-ETH is an interface module for RAD devices, used for converting the Ethernet
(10BaseT) electrical levels to the host device TTL levels. It also converts the
Ethernet protocol to HDLC to enable long-distance transmission and avoid the
Ethernet collision limitation.
IR-ETH includes an internal, self-learning Ethernet bridge, which enables a high
performance link between two Ethernet segments at a low transmission rate. The
low-speed HDLC transmission is sent over the link and then converted back to an
Ethernet signal at the remote unit.
IR-ETH has a 10BaseT interface complying with the IEEE 802.3 standard,
terminated in an RJ-45 shielded connector, which can operate over UTP and STP
media. The Ethernet port with 10BaseT operates in full-duplex mode.
The optional built-in Ethernet Bridge is a high performance remote, self-learning
bridge. It is ideal as a LAN extender or segmenter over E1 link applications. The
bridge operates as a media access (MAC) layer remote bridge with self-learning
capabilities. It learns and automatically recognizes the addresses of the nodes
attached to the local LAN (the LAN directly attached to the FCD-E1 interface), and
uses this information to filter the LAN traffic. The address information is stored in
tables, which can store up to 10,000 addresses. The address information is
automatically updated (aging time is 5 minutes, that is, if no frames are received
from a node for 5 minutes, the node address is automatically removed from the
tables to ensure that only fresh addresses are used).
Therefore, the bridge blocks the packets addressed to local nodes, and forwards
through the FCD-E1 link only multicasts, broadcasts, and packets addressed to
nodes attached to the remote LAN.
Filtering and forwarding can be performed at a rate of up to 15,000 packets per
second (provided the bandwidth selected on the E1 link is sufficient to carry the
resulting payload rate). When bridging is not necessary, e.g., for LAN extender
applications, the user can disable the bridge. In this case, the FCD-E1 operates as a
repeater that transfers transparently all the traffic to the remote end.
The Ethernet channel interface connects to the TDM bus through a bus interface
similar to that of the data channel. The throughput available to the external
equipment is determined by the data rate configured by the user.
The remote bridge operates at the physical and data link layers of the OSI model,
and is therefore completely transparent to higher-level protocols, such as TCP/IP,