Friday, October 14, 2005

Troubleshooting Difficulties Network

Troubleshooting Difficulties
Disabling autonegotiation can result in physical layer problems going
undetected.
Link partner, cable problems, and other Data Link layer issues are
hidden from the
administrator and manual examination of driver statistics is required.
s
Unable to detect bad cables
s
Unable to detect link failures
s
Unable to check link partners capabilities
s
Unable to move systems from one port to another or to another switch or router
s
Unable to determine performance issues on higher layer applications
s
Unable to implement Pause Frames (Flow Control)
s
Difficulties in determining where system has forced setting configured
(/etc/system and driver.conf using ndd in startup script
Link syncing between link partners may not happen and the link may not come up
when autonegotiation is absent on 100BASE-T (UTP) copper.
Example of hme interface with duplex mismatch:
hme0 has negotiated and failed back to HDX and experiencing crc babble and
late_collisions.
Console> show port negotiation 4/1
Port
Link Negotiation
----- ----------------
4/1 enabled
# kstat -p hme:0::'/collisions|framing|crc|code_violations|tx_late_collisions/'
hme:0:hme0:code_violations
0
hme:0:hme0:collisions
16720
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Ethernet Autonegotiation Best Practices • July 2004
Example of hme interface with duplex mismatch:
hme1 is forced to FDX and experiencing framing, crc, and code_violation errors.
Example of switch port with duplex mismatch:
Port 11/22 has been forced to FDX (Full Duplex) but link partner is in HDX (half
duplex), resulting in FCS (Frame Check Sequence) and runt errors.
Check that port negotiation is enabled on the switch:
hme:0:hme0:crc 0
hme:0:hme0:framing
0
hme:0:hme0:tx_late_collisions 5706
# kstat -p hme:1::'/collisions|framing|crc|code_violations|tx_late_collisions/'
hme:1:hme1:code_violations
147
hme:1:hme1:collisions 0
hme:1:hme1:crc 283
hme:1:hme1:framing
8
hme:1:hme1:tx_late_collisions 0
Console> show port counters 11/22
Port Align-Err FCS-Err Xmit-Err
Rcv-Err
UnderSize
----- ---------- ---------- ---------- ---------- ---------
11/22
0
572968
0
0
0
Port Single-Col Multi-Coll Late-Coll Excess-Col Carri-Sen Runts
Giants
----- ---------- ---------- ---------- ---------- --------- --------- ---------
11/22
0
0
0
0
0 9765322
0
Console> show port negotiation 4/1
Port
Link Negotiation
----- ----------------
4/1 enabled
Console> show port negotiation 4/1

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