Last week I had to change the default gateway for an EMC VNX5300 storage system.  The SPs network properties, its IP address, subnet mask, and default gateway cannot be changed in Unisphere but must be changed through the control station using the steps below.  It is important to note that the following steps apply only to FILE OE versions at 7.0.35 and later.  I performed the steps below on FILE OE version 7.1.55.3 and would recommend calling into EMC support to verify the steps on your storage system before attempting. 

The system I was working on how only a single control station.  The IPs are as follows:

CS0     10.11.200.50
SPA     10.11.200.52
SPB     10.11.200.53

Basically, I did these steps to change the default gateway from 10.11.200.1 to 10.11.200.254. 

1. Log in as user nasadmin, then $ su to root user

2. Stop the Proxy ARP service to return the SPs to the default internal address scheme:
# /nas/sbin/clariion_mgmt -stop
# ping 128.221.252.200 [SPA]
# ping 128.221.253.201 [SPB]

3. Change the IP addresses of the SPs by using the following and verify that the changes succeeded:
# /nas/sbin/clariion_mgmt -modify -spa_ip 10.11.200.52 -spb_ip 10.11.200.53
# ping 10.11.200.52
# ping 10.11.200.53
# tail /etc/hosts
10.11.200.52 A_FNM00104600113 SPA # CLARiiON SP
10.11.200.53 B_FNM00104600113 SPB # CLARiiON SP
# nas_storage -c -a
Discovering storage on c250 (may take several minutes)
done
# /nas/sbin/navicli -h 10.11.200.52 domain -list
# /nas/sbin/navicli -h 10.11.200.53 domain -list

4. Change the IP address on CS0 and then verify that CS0’s IP address is properly updated to the domain:
# nas_cs -set -ip4address 10.11.200.50 -ip4netmask 255.255.255.0 -ip4gateway 10.240.200.254
OK
# nas_cel -list
id name owner mount_dev channel net_path CMU
0 c250 0 10.240.200.50 FNM001046001132007
# /nas/sbin/navicli -h 10.11.200.52 domain -list
# /nas/sbin/navicli -h 10.11.200.53 domain -list
# grep /etc/hosts
10.11.200.50 c250.emc.com c250