This is a summery of how you can connect a layer 2 (point to point/direct connection) between two Sonicwalls using SonicOS Enhanced 5.8. This is also a summery of how you can use the second Sonicwall’s WAN as a failover connection for the first Sonicwall.
On the first Sonicwall, plug layer 2 connection into an interface. For this example we will use X5.
IP Assignment: Static
IP Address: 10.10.10.1
Default Gateway: 10.10.10.2
DNS Server 1: 184.108.40.206
DNS Server 2: 220.127.116.11
DNS Server 3: 18.104.22.168
On the second Sonicwall, plug layer 2 connection into an interface. For this example we will use X5.
Mode/P Assignment: Static IP Mode
IP Assignment: 10.10.10.2
For failover and the ability to use the second Sonicwall's WAN for the first Sonicwall's WAN...
On the first Sonicwall
Network->Failover & LB
Check Enable Load Balancing
Check Respond to Probes
In the Groups section Click Configure for Default LB
Type: Basic Failover
Check Preemp failback to preferred interfaces when possible
Highlight X5 interface and click Add
Order desired interface and click OK
Click Configure for X5
Select Logical/Probe Monitoring enabled
Select Probe succeeds when either Main Target or Alternate Target responds
Main Target: Ping (ICMP) Host: 22.214.171.124
Alternate Target: Ping (ICMP) Host: 126.96.36.199
Default Target IP: 188.8.131.52