HP J2600A, Installation And Reference Manual

Page: 56 / 138

Auto-Segmentation
The Basic Feature
The hub will automatically segment (temporarily disable) a network
port if a collision condition exists for an excessive duration (between
1024 and 2048 bit times) or occurs during each of 32 consecutive
attempts to transmit. The hub monitors the segmented port and
automatically re-enables the port when a minimum length packet can be
successfully transmitted or received without a collision occurring.
Excessive collisions may be caused by faulty wiring. If a port’s transmit
(Tx +/-) wires have been shorted to the receive (Rx +/-) wires of any
port, a collision will be detected when that port attempts to transmit. If a
port’s receive (Rx +/-) wires are not connected properly, collisions may
occur because the hub cannot detect the presence of network traffic on
that port and may thus transmit at inappropriate times.
A port may occasionally also become segmented when network traffic is
extremely heavy causing an abnormally high collision rate.
Intelligent Segmentation Recovery
(Available on hubs with the HP Ethernet SNMP Module)
Intelligent Segmentation Recovery makes it more difficult for a problem
port to automatically re-enable itself to send traffic on the network. For
a port configured with Intelligent Segmentation Recovery, once it has
been disabled due to extended or excessive collisions, it will be
automatically re-enabled only when it is able to
transmit a minimum
length packet without a collision condition occurring. This feature
prevents a port from re-enabling itself when it just receives traffic from
the attached node or when it receives reflected noise or crosstalk
caused by faulty wiring.
The Intelligent Segmentation Recovery feature is enabled through the
“Robust” function in HP Stack Manager or the RObustness command in
the ASCII console interface. The default setting is OFF.
Late Collision Monitoring
(Available on hubs with the HP Ethernet SNMP Module)
When this feature is enabled, the hub will automatically disable (turn
off) a network port when persistent late collisions are detected on that
port.
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Hub Reference
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