ASA5520 is directly connected to 7600 router, IP .1 and .62 in same subnet. 7660 does not have mac/IP od ASA outside interface in his arp table, so it can not return packets to ASA. When we put ASA5505 with same software 7.2.2 and same configuration, everything is working! After issuing "no sysopt no proxyarp outside" on outside interface on ASA5520, arp is correctly resolivng, but NAT/PAT is not working, so we are on the same point again.
Is there any idea?