SDWAN: Virtual paths are flapping.
Article ID: CTX232033
Updated On:
Description
The virtual paths are fluctuating from GOOD to BAD/DEAD and vice versa. This can be checked under Monitoring > Statistics > Path Summary table.
The Loss % of upload paths of DC to Branch SDWAN were showing 43 % and 8 % as shown below:
Resolution
Enable Active Detect MTU under the WAN link settings between DC and Branch as shown below:
NOTE:
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Some times even if you perform ping or iPerf test from SDWAN, the Packet drops or LOSS will not be shown. However,the path Summary table will still display the LOSS %. This reason being for not showing the packet loss or drops during the ping or iperf test is, the intermediate devices of WAN network doesn't send ICMP Fragment needed message although its MTU size is lesser than the actual packet size.
Problem Cause
Packet drops on the intermediate devices of WAN network due to the MTU size of intermediate device was less than the actual packet size.NOTE:
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Some times even if you perform ping or iPerf test from SDWAN, the Packet drops or LOSS will not be shown. However,the path Summary table will still display the LOSS %. This reason being for not showing the packet loss or drops during the ping or iperf test is, the intermediate devices of WAN network doesn't send ICMP Fragment needed message although its MTU size is lesser than the actual packet size.
Issue/Introduction
The upload paths of DC SDWAN to Branch SDWAN are flapping GOOD to BAD/DEAD. Whereas, the download path between DC SDWAN and Branch SDWAN were staying GOOD.
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