I have the following config:

Two SQL 2005 servers with ISCSI SAN.  I am getting the following error on the cluster nics.  Error: Cluster1 Unreachable.  Any ideas what causes this.  I am unable to ping th eother Server cluster IP from one another.

(1) SQL 2005 Server
NIC 1 - NET
IP 10.9.30.14
Subnet 255.255.255.0
Gateway 10.9.30.1

NIC 2 - CLUSTER
IP 10.9.31.14
Subnet 255.255.255.0
Gateway

(2) SQL 2005 Server
NIC 1 - NET
IP 10.9.30.15
Subnet 255.255.255.0
Gateway 10.9.30.1

NIC 2 - CLUSTER
IP 10.9.31.15
Subnet 255.255.255.0
Gateway

Try to ping the two servers from any client 

if ok ,check firewall  and enable ping service.

use command

from server 10.9.30.14 run command: tracert  10.9.30.15

and vice versa. It should work

The only experience I've had with multiple NICs was with a server that had a working NIC and a faulty NIC, and the faulty one had to be removed to get the performance up to normal speed.