R3303-HP HSR6800 Routers Layer 2 - WAN Configuration Guide

• If two routers are connected back-to-back, make sure that 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 that 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 that 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 that

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 that the optical fibers are correctly connected to ATM interfaces. 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.

Solution

Determine if this fault results from enabling OAM F5 Loopback cell transmission and retransmission

detection or OAM continuity check. When two ATM devices are connected, the VPI/VCI value of the

PVCs on the two devices must be the same. If 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.

Ping failure after PPPoA configuration

Symptom

The PVC state is UP, but after applications like IPoA are configured, the remote node cannot be

successfully pinged.

Solution

Make sure that the remote node supports the same application as configured on the local node. For

example, if the local node uses PPPoA, the remote node should also use PPPoA.