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Link report error in PPPoA application
Symptom
When PPPoA is used, the link does not report UP.
Solution
See "Link state error in IPoA application."
Ping failure
Symptom
The physical layer of the interfaces and the line protocol are both UP, but when tested with the ping
command, the two ends are mutually unreachable.
Solution
• If IPOA is used, make sure the IP protocol address mapping is configured correctly. If the
interfaces of two routers are connected back-to-back, the local PVC mapped to the remote IP
must have the same VPI/VCI value as the remote PVC mapped to the local IP. In addition, the
IP addresses of the two ends must also be in the same network segment.
• If two routers are connected back-to-back, make sure at least one of interfaces uses internal
transmission clock (master). Or, if the routers are connected to the ATM network, the
transmission clock should be set to line clock.
• Check the ATM interfaces of the two sides to make sure they are of the same type, for example,
both are multimode fiber interfaces or both are single-mode fiber ports, or both are multi-mode
fiber interfaces but connected using single mode. If a multimode fiber interface and a
single-mode fiber interface are directly connected, they can communicate in most cases, but
sometimes with frequent packet dropping and CRC errors.
• If the two ends are PPPoA, make sure their IP addresses (should be in the same network
segment) and authentication parameters are correctly configured.
• If, according to the ping command, small packets can pass but big packets cannot, make sure
the mtu configurations of the two router interfaces are the same.
ATM interface state error
Symptom
The interface state of ATM is DOWN.
Solution
Make sure the optical fibers are correctly connected to ATM interface. There should be two optical
fibers, one for receiving information and one for sending information. The two are not exchangeable.
If they are wrongly connected, the interface state of ATM cannot be UP.
If two routers are connected back-to-back, check if neither of the two ATM interfaces enables internal
transmission clock. By default, routers use line clock. If two routers are connected back-to-back, one
of them should be configured as internal transmission clock with the clock master command.
PVC state is down while ATM interface state is up
Symptom
The interface state of ATM is UP, but the PVC state is DOWN.
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