Troubleshooting atm, An atm interface is always down, Symptom – H3C Technologies H3C SR8800 User Manual
Page 24: Solution, Pvc state is down while atm interface state is up, Pinging opposite end attempts always fail
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Troubleshooting ATM
An ATM interface is always down
Symptom
The state of an ATM interface is always down.
Solution
Check the fiber connections of the ATM interface for inverse connections. The ATM interface can go up
only when the transmit fiber and receive fiber are correctly connected.
If two routers are connected back-to-back, check the ATM interfaces for the same clock mode. By default,
the clock mode on a router is slave, namely, adopting the line clock. If two routers are connected
back-to-back, you must configure the clock mode at one side as master to provide clock reference, while
the other side adopts the slave clock mode.
PVC state is down while ATM interface state is up
Symptom
The state of a PVC is down while its ATM interface is up.
Solution
Check if this fault results from enabling OAM F5 Loopback cell transmission and retransmission detection
or OAM continuity check. When two ATM routers are connected, the VPI/VCI value of the PVCs on the
two routers must be the same. Provided that OAM F5 cell transmission and retransmission detection or
OAM continuity check is enabled, and the VPI/VCI value of the remote node (connected directly with the
local node) is not the same as the local node, the local PVC state cannot change into UP.
Excessive packet drops/CRC errors or interface flapping
occurs
Symptom
Two routers are connected back-to-back and can ping each other, but excessive packet drops and CRC
errors or interface flapping up and down occurs occasionally.
Solution
Check the connecting ATM interfaces for fiber type inconsistency. If one side is a multi-mode fiber-optic
interface while the other side is a single-mode fiber-optic interface, replace one interface to make sure
that the same fiber-mode interfaces are used.
The symptom is occasional with the connection between ATM interfaces of different fiber-optic modes,
which can work normally in most cases.
Pinging opposite end attempts always fail
Symptom
The physical layer and the line protocol of an ATM interface are both up, but the opposite end cannot be
pinged.