Testing Segments Attached To The Hub - Cabletron Systems MRX Installation Manual

TESTING AND TROUBLESHOOTING
2. If the LINK LED for any of the twisted pair segments (Ports 1-12
or SPIM-T/T1) flashes when the HUB is powered on or when the
segment is first attached, it indicates a polarity reversal for that
segment. If a reversed polarity condition is discovered, the
segment should be removed from the network and wired correctly
(according to the connector wiring shown in Chapter 2,
Requirements/Specifications). This will avoid the potential
for future compatibility problems.
3. If the remote station is ready and the LINK LED is lit, but no
data is being passed through the port, one of two conditions may
exist:
• The port has been disabled by network management or
• The port has been segmented either because the collision
detector was on for more than 210 sec. or 33 consecutive
collisions were detected on the attached segment. The
affected link will remain segmented until a good packet is
transmitted/received without collisions.
If the LINK LED is still not lit, contact Cabletron Systems Technical
Support.

4.2 TESTING SEGMENTS ATTACHED TO THE HUB

The Ethernet links connected to the HUB can be tested to determine
if they comply with IEEE 802.3 specifications. This is done by using
two Ethernet node testers, such as Cabletron Systems LAN-MD™
attached in place of the Ethernet devices normally attached on any
two links. Figure 4-1 shows several methods for connecting the
LAN-MD to test different media types and links connected to the
HUB. The LAN-MDs exchange valid data packets for end-to-end
testing.
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