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Cisco Bug: CSCvt49314 - AnyConnect Reconnects Multiple Times after an Active DTLS Session Reverts to TLS

Last Modified

Oct 16, 2020

Products (1)

  • Cisco AnyConnect Secure Mobility Client

Known Affected Releases

4.3(1095) 4.4(243) 4.5(58) 4.6(362) 4.7(136) 4.8(175)

Description (partial)

Sometimes UDP 443 traffic may become blocked during an active DTLS session; for example, when a user roams from one wireless network to another. After several UDP DPDs are missed, the AnyConnect session will fall back to TLS (TCP 443).

After falling back to TLS, the AnyConnect client will continue to send DPDs via UDP in an attempt to reconnect DTLS. Because UDP is blocked, these DPDs fail. The client goes through the "Reconnecting" phase up to three times, unexpectedly reconnecting the TLS channel each time, before the attempts to reconnect DTLS cease.  After this the TLS connection stabilizes.

The behavior is applicable to the following AnyConnect versions:

- 4.3.01095 (4.3MR1) and higher 4.3.x versions
- 4.4.x
- 4.5.x
- 4.6.x
- 4.7.x
- 4.8.x
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