vCenter 5 Mgmnt Network Question

[JustyC]

Our VMware environment is expanding - we are in the process of re-architecting some network connections.  Can anyone offer some recommendations or best practice on the following questions.
1).  On new host builds can we use a different IP range for the management network without causing issues with subnets already used by existing hosts ?  Can we change the IP of existing hosts without a rebuild ?
2).  We are in very short supply of Cisco ports.  My Network Services team asks if we can combine management network traffic with vMotion traffic over the same physical connection.  What would the ramifications

      be if we did allow both ?  Unless we have a host failure any vMotion activity is controlled manually and very light.  We are working (on-going project) on a DR plan, but have nothing in place.

[rcporto]

1). On new host builds can we use a different IP range for the management network without causing issues with subnets already used by existing hosts ? Can we change the IP of existing hosts without a rebuild ?

Yes for both, but make sure if vCenter are on different subnet with a firewall in place, you will need open some network ports.

2). We are in very short supply of Cisco ports. My Network Services team asks if we can combine management network traffic with vMotion traffic over the same physical connection. What would the ramifications be if we did allow both ? Unless we have a host failure any vMotion activity is controlled manually and very light. We are working (on-going project) on a DR plan, but have nothing in place.

Not a best practice, but you can... but take in mind that if you have a heavy load of vMotion traffic, you management network may be disrupted.

[JustyC]

At this time all hosts are here on the corporate campus.  Not sure if that will be the case when we implement a DR plan.  Would there be any performance benefit if all hosts were on the same subnet ?

Also, half the hosts are ESX 4.0.  We plan to replace those with new hardware and move up to 5.5.  In the meantime if we had to could the management IP be changed to a new subnet without a rebuild ?

[bayupw]

Just want to add some of my opinion on number 2.

2).  We are in very short supply of Cisco ports.  My Network Services team asks if we can combine management network traffic with vMotion traffic over the same physical connection.  What would the ramifications

      be if we did allow both ?  Unless we have a host failure any vMotion activity is controlled manually and very light.  We are working (on-going project) on a DR plan, but have nothing in place.

How many NICs/vmnic do you have that will be shared for management network and vMotion?

If you have at least 2 vmnic connected to different switches, you can configure

1st vmnic: Management - Active/Standby, vMotion - Standby/Active

2nd vmnic: vMotion - Active/Standby, Management - Standby/Active

[JustyC]

Interesting comment.  All our hosts have 2 vmnics (1 vSwitch) for the management console.  We usually create a separate vSwitch just for vMotion and assign 1 or 2 vmnics.  However, lately due to limited physical ports

we've been putting vMotion in the management vSwitch.  Both vmnics in the management vSwitch are active. 

[bayupw]

Is it 2x1GbE or 2x10GbE?
If it is 2x10GbE and you have vSphere Ent+, I would go for single VDS design and use NIOC

See this blog post on some NIC design layout: VMware vSphere 5 Host NIC Network Design Layout and vSwitch Configuration [Major Update] | Tech Blog | Blog

[JustyC]

Great article on Host Nic Network Design.  For us here the standard has been 2x1GB NICs per vSwitch.  It would appear utilizing 10 GBe would be a big plus.

However, we could not use it for iSCSI as our storage platform only supports 1 GBe.