Choosing a Network Pool type for my Evaluation Cloud

[chadmichael]

I've set up a vCloud Director roughly following the appliance installation found in the vCloud "evaluation" guide.  That guide assumes that VXLAN backed network pools will be used; apparently, I don't have the switch support for that scenario.  Rather than sort that out, I'd like to just get my evaluation cloud up and running.  With this in mind, I'm trying to figure out whether a Cloud Isolated Network will work for me. 

I have:

1) a distributed switch

2) vlans and ip ranges available to me

Seems like this is all I need to be successful; I guess the vlan is optional but I'll need to specify one of my vlans, as I understand it.  I'm a bit new to these networking topics, but if there are multipel vlans on the phsyical layer, I have to specify one for the network pool, correct?

My main question is about the MTU.  Is the MTU increase only about performance?  I understand that the tunneling information makes the total frame bigger than the standard 1500 bytes, and that cause fragmentation, but if this only performance, then my evaluation needs don't require that I make the MTU adjustment, at least as far as I can see. 

Thoughts?

[IamTHEvilONE · Accepted solution]

Correct about 1 VLAN to 1 Network Pool ration.  Think of it as a way of privatizing the multi-cast traffic that is vCNI (vCloud Network Isolation) ... which is a type of network pool.  For vCNI, i think you get 1000 isolated networks per Pool (which has 1 VLAN).

No IPs actually need to really exist on this, since it's all multi-cast traffic (afaik).

MTU is about performance mostly.  If you want to use vCloud Network Isolation ... you can do it at 1500 MTU ... you create the pool on a specific VLAN (which exists on your network fabric) and once the pool is created ... drop the MTU in the properties of the pool to 1476

[chadmichael]

Correct about 1 VLAN to 1 Network Pool ration.  Think of it as a way of privatizing the multi-cast traffic that is vCNI (vCloud Network Isolation) ... which is a type of network pool.  For vCNI, i think you get 1000 isolated networks per Pool (which has 1 VLAN).

No IPs actually need to really exist on this, since it's all multi-cast traffic (afaik).

No IPs?  Not sure I understand.  Isn't it possible to have some of the vm's inside the dynamically allocated vapp networks exposed directly into the subnet space of the external network? 

MTU is about performance mostly.  If you want to use vCloud Network Isolation ... you can do it at 1500 MTU ... you create the pool on a specific VLAN (which exists on your network fabric) and once the pool is created ... drop the MTU in the properties of the pool to 1476

That's a nice option to have.  But, even this is only necessary for performance reasons, correct?

[IamTHEvilONE]

vApp networks will have a vShield Edge device deployed as a router as required.  The multi-cast aspect of it doesn't require IPs.  The network pools represent technologies that create isolation on the same VLAN ... so we essentially broadcast all the traffic between all the hosts.  the reason is ... we take the default MTU of 1500 and strap 24 bits on the front of it ... the bits basically state it's from Network Pool X + Isolation ID Y ... so that the receiving ESX host can differentiate them.  The VLAN itself, is used to ensure that only the ESX hosts get this data ... it's pretty much useless anywhere else ... so the VLAN can be trunked to only the ESX hosts to reduce chatter on the rest of your network.

And yes, not having an MTU above 1500 would only affect performance ... but if you monitor traffic ... you might get warnings that you have packet fragmentation.