[strongSwan] How to sync the SN in SA in the backup server?

[Martin Willi]

Hi,
      
> So I want to know weather there is a way to know the SN in the
> outbound SA? Is there a IKE information message carrying such payload?
> Or is it a way to back up the SN very conveniently?

There is an IKEv2 extension [1] that add client synchronization
functionality, but we don't support it. We have our own ClusterIP based
HA solution that does not need a protocol extension, see [2].

Regards
Martin

[1]http://tools.ietf.org/html/rfc6311
[2]http://wiki.strongswan.org/projects/strongswan/wiki/HighAvailability