Netscreen and SonicWall interoperate problem

Hi,

I'm having issue with interoperation, the Netscreen 5XT and SonicWall Pro . I set the NS for using VPN, the Untrusted I/F is 10.0.0.2, the Trusted I/F is 172.16.0.2, its default-gw is 172.16.0.1. The SonicWall has 10.0.0.1 and 172.16.0.1 I/F, its default-gw is

1. PCs to Sonic (and Internet) : reachable
2. Sonic to PCs : reachable
3. NS to PCs : reachable but,
4. NS to Sonic: unreachable

I tried to ping NS to Sonic. Initial once or twice, ping succeed, then ping fail (timeout). At that point, I dumped packets, but no packets (ARP, ICMP)

.1 .1 .3 PCs --- hub --- Sonic --- hub --Router --- Internet | | +----- NS 5XT -----+ .2 .2 |=== Local ===| |== DMZ ==| (172.16.0.0/24) (10.0.0.0/24)

So, I disconnected NS's Untrust I/F, NS to Sonic is reachable. I re-connected NS's Untrust I/F, NS to Sonic is unreachable.

I guess the Sonic's MAC problem. I get arp: 10.0.0.3 00xxxxxxxxxx trust-vr/eth3 VLD 599 0 0 10.0.0.1 004010xxxxx1 trust-vr/eth3 VLD 1100 0 0 172.16.0.1 004010xxxxx1 trust-vr/eth1 VLD 320 0 0

Any ideas?