AR1200 SIP trunk cannot change back after GRE tunnel switcover

Between AR1220C and AR1220E, connect to ISP and reach each other. GRE over IPSec also be set up between the two device. when the GRE tunnel is ok, the SIP voice traffic will go through the GRE tunnel. If the GRE tunnel down, the SIP voice traffic will go out with NAT and reach to each other. The issue is that, when GRE tunnel down, the SIP voice switch to NAT. But when the GRE tunnel recover, the SIP vioce traffic cannot switch back to GRE tunnel.

Configure on AR1220C:

#

interface Dialer1

 link-protocol ppp

 ppp chap user xxx

 ppp chap password xxx

 mtu 1492

 ip address ppp-negotiate

 dialer user gardppp

 dialer bundle 1

 nat outbound 2999 

 zone WAN

 ntp-service in-interface disable

#

1.When the GRE tunnel is up, the VOIP traffic go through GRE tunnel. It means that the routing to each other is right.

2. When the GRE tunnel is down, the VOIP traffic go out with NAT, and reach each other. It means that the path switchover is ok.

3. When the GRE tunnel up again, the routing to the peer site can learn through the GRE tunnel. At that time, the nat session table still active. As the nat session table has higher priority than the routing table, so the voice traffic still go through NAT.

4. When customer reset the NAT session, the current session will be reseted. There is no nat session table, the traffic will check the routing table again, the traffic will go through GRE tunnel again.

The nat session table has higher priority than the routing table, so the voice traffic still go through NAT. When customer reset the NAT session, the current session will be reseted. There is no nat session table, the traffic will check the routing table again, the traffic will go through GRE tunnel again.