Allied Telesis AT-MR840TF - Manual (Page 23)

AT-MR820TR Hub Installation Guide
3
Functional Description
The AT-MR840TF hub incorporates the latest technologies, including a custom
Application Specific Integrated Circuit (ASIC) and Surface Mount Technology
(SMT). Employing state-of-the-art technologies results in enhanced
functionality, increased reliability, and improved performance and as detailed
in the following list of features:
Packet Regeneration
Packet regeneration is a high-performance network feature that includes the
regenerating of the packet preamble, retiming of data packets, and the
extension of collision fragments. When transmitting a packet, the hub ensures
that the outgoing packet complies with IEE 802.3 specification in terms of
preamble structure, signal amplitude, and timing characteristics. Data packets
repeated will contain a minimum of 56 preamble bits before start-of-frame
delimiter. In addition, the hub restores signal symmetry to the repeated data
packets, removing jitter and distortion caused by the network cabling.
Link Integrity
The IEEE 802.3 defined link integrity test function continually monitors the
twisted pair cable to ensure link continuity of the receive pair between the user
node and the hub.
Autopartitioning
Also known as segmentation, each segment will be automatically partitioned
whenever 32 consecutive collisions occur on the segment. One valid packet will
reset the segment and return it to the auto reconnecting segment. Any of the
twisted pair ports can be partitioned if the frequency of collisions becomes
excessive. The enabled network port is partitioned if one of the following
conditions occurs on that port:
❑ A collision condition exists continuously for more than 2048 bit times
❑ A collision condition occurs during each of the 32 consecutive attempts
to transmit to that port.
When there is no more collisions in the partitioned port and activity of 512 bit
times or more is detected, the partition is released and the port is reconnected.
MR840TF_Book Page 3 Tuesday, November 11, 1997 3:46 PM