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8-24
Cisco MDS 9000 Family Troubleshooting Guide, Release 3.x
OL-9285-05
Chapter 8 Troubleshooting Ports
Common Problems with Port Interfaces
3. Offline state (OLS):
a. OLS transmit substate (OL1)
b. OLS receive substate (OL2)
c. Wait for OLS substate (OL3)
4. Link failure state:
a. NOS receive substate (LF1)
b. NOS transmit substate (LF2)
The Cisco MDS 9000 Family switch maintains port counters for link initialization ordered sets,
including OLS, LRR, and NOS for fabric connections, as well as primitives for arbitrated loop
connections on FL ports and TL ports. Understanding the link initialization flow and viewing the port
counters using show interface can be useful when you troubleshoot port initialization problems.
Table 8-6 displays the reasons for a link flap.
Table 8-6 Link Flap Reasons Initiated by a Device Connected to the Switch Port
Reason Description
Sync Loss A synchronization loss condition persisted for more than 100 milliseconds.
Look at the Invalid Transmission Word Count to check whether the physical
link is really bad and if that caused the loss of synchronization. Sometimes this
is not necessarily a problem with the physical link, but with the way some
devices initialize the link. Use attach module to connect to the module and
then use the show hardware internal debug-info interface CLI command.
See Table 8-2.
Loss of signal A signal loss condition persisted for more than 100 milliseconds. Look at the
Invalid Transmission Word Count to check whether the physical link is really
bad and if that caused the loss of synchronization. Sometimes this is not
necessarily a problem with the physical link, but with the way some devices
initialize the link. If the link does not come up after a flap, then probably the
other end is in a shutdown state or the cable is broken. You can check for the
broken or disconnected optical link by using the show hardware internal
fc-mac port port gbic-info CLI command.
Note You must use the attach module CLI command to access the FC-MAC
show commands
NOS received A NOS received condition is detected. If the other end is an MDS port, then
the NOS is transmitted by the other end in one of the following conditions:
• A signal loss or sync loss condition is detected.
• The port is administratively shut down.
• The port is operationally down.
OLS received An OLS received condition is detected.
LR received B2B Link reset (LR) failed because of the receive queue (in the queue engine) not
being empty.
Cr loss Too many credit loss events occurred.
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