Appendix D Link Integrity Test Function - Bay Networks 281xSA Using Manual

Appendix D Link Integrity Test Function

893-743-A
Model 281xSA Ethernet Hubs support the IEEE 802.3i 10BASE-T Link
Integrity Test function on all their 10BASE-T ports. This function monitors
the UTP receive data wire-pair and determines the integrity of the UTP link
segment. The 10BASE-T transceiver located at the other end of the link
segment also monitors its UTP receive data wire-pair for link integrity. Thus
both data wire-pairs of the UTP link segment are tested for link integrity.
At all times, the Model 281xSA hub transmits either data or an idle signal,
which is called TP_IDL (twisted-pair idle signal). TP_IDL is transmitted in
the absence of data and consists of a repetitive sequence of 100-nanosecond
(ns) pulses occurring every 16 milliseconds (ms). The 100-ns pulses are called
Link Test Pulses (LTPs).
All Model 281xSA hub ports monitor their receive wire-pair for data and
LTP activity. If neither data nor LTPs are detected within 100 ms, the port Link
LED goes out to indicate no link status. While there is no link integrity, the
Model 281xSA hub port does not send data to the UTP wire, and the port
receiver does not forward data from the UTP wire to the concentrator until link
integrity is restored.
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