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H3C Technologies H3C SecPath F1000-E User Manual

Page 62

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Symptom 2: Data transmission fails. A connection is setup but data cannot be transmitted. For
example, the LAC and LNS cannot ping each other.
Analysis and solution:
Possible reasons for data transmission failure are as follows:

Step3

No route is available. The LAC (or LAC client) must have a route to the private network behind the LNS
and the LNS must have a route to the private network behind the LAC. Otherwise, data transmission fails.
You can use the display ip routing-table command on the LAC (LAC client) and LNS to check

whether the expected routes are present. If not, configure a static route or configure a dynamic routing

protocol.

Step4

Congestion occurs on the Internet backbone and packet loss ratio is high. L2TP data transmission is

based on UDP, which does not provide the packet error control function. If the line is unstable, the LAC

and LNS may be unable to ping each other and L2TP applications may fail.