Your design is like mine (except for the access sw families)... I hope it's the best :)The HA is very powerfull and it works really well. I tested it and I'm using it in my LAN. Very short downtimes!I have tried the config sync... Excellent idea; doe...

Try debugging the isdn (debug isdn q931 and/or debug isdn q921) to see if something is happening to the isdn link.I think that you are facing a link up-link down maybe due to inactivity on the isdn link. I suppose you have configured an acl that "tel...

You can create an ACL that blocks icmp (deny icmp) or if you want to use a port number, you have to disable the "echo" replies (udp port 7).

I think you were asked to use 2 trunks between the 8540 and each switch just for PHYSICAL redundancy.Regards,JPL

From the network point-of-view, you cannot do anything.JPL.