Administration - Save configuration, Firewall

inspect-state– monitor the pings for echo replies and allow them back in

oos 10 t=3 c=3 d=3 – if 3 consecutive pings fail, deactivate PPP 1 and start recovery procedures after 10 seconds. This 10 second timer could be increased (by editing the firewall rule) to prevent the Digi Transport from switching rapdily between PPP 1 and PPP 4 in the case where PPP 1 works intermitantly. This “oos 10” can be thought of as a de-bounce timer in the context of this application note.

r=ping,10,5 rd=1 dt=1 – during recovery, test the link every 10 seconds with a ping, allow 5 seconds for the response to each ping, if the recovery fails deactivate the interface and deactivate the link before trying again

Rule 2 then allows all other traffic through.

For a more detailed explanation of the above firewall keywords refer to the Sar/OS reference manual “ftp://ftp1.digi.com/support/documentation/Digi Transport and Sarian User Guide.pdf”

Finally turn the firewall on for PPP 1 to activate the ICMP monitoring and recovery.

Configuration - Interfaces > PPP > PPP 0 - 4 > PPP 1 > Standard

Parameter

Firewall

Setting	Description
ON	Switches the firewall on for this interface

Click OK

2.5 Save configuration

Save your configuration as the power up configuration.