So I'm planning to install my first ever san! (ok, all those who say NOOB can leave). I'm running 2 esxi 4u1 servers, they have individual nics for each vm. All vm's attach to a stack of dell 6248 switches. I'm running a 172.16 subnetted class b.

Now I want to add my MD3000I san. I want to keep it's ISCSI traffic isolated, I'm also setting it up for redunancy, so I buy 2 cheap dell 2724 managed switches. Add 2 more physical nic ports to each of my Esxi servers.

Now I setup my san as suggested in : http://www.delltechcenter.com/page/VMware+ESX+4.0+and+PowerVault+MD3000i?zone=addthis&sms_ss=email

what I'm having trouble wrapping my head around is the IP addressing specific for my network. Should I setup the 192 class c's as suggested in the above article, or will I need to increase my existing subnet for more ip's and put the san in an isolated 172.16 address block so that the vm's can see it? Would setting up the 192 addresses help keep my ISCSI traffic isolated?

Welcome alamosa!

You have a few options:

(1) you can setup up a 172.xx Class B subnet, where xx is not equal to 16 to keep your iSCSI traffic isolated- you can handshake your 2 additional pNICs w/ your MD3000i iSCSI host ports using MDSM & vCenter. This would be similar to setting up the 192 addresses to keep your iSCSI traffic isolated. If you are ok w/ a class b network, your 192 network can be kept as a class b.

(2) you can enable and setup VLAN support on your ESXi host servers for iSCSI & MD3000i for iSCSI traffic.