Accepted Solutions
Scenario:
I have 4 pNICs on my ESX 4 host that I want to use for my VM Network vSwitch (Port Group). I have 2 physical switches that I want split my 4 pNIC connections across for redundancy.
Questions:
Do I need to do anything special on the pSwitch side to configure the NIC ports to handle all 4 pNICs going to a single vSwitch?
Not if you use any load balancing algorithm other than IP Hash.
What about 2 to each pSwitch?
Ditto
If I choose to trunk these links with 802.3ad (2 pNICs going to each pSwitch):
Will this require that the vSwitch is configured as IP Based Hashing or can this be the default of Port ID load balancing?
Yes - IP Hash is required when you use 802.3ad.
Does this config require a special config/feature between the pSwitches to handle the cross switch 802.3ad? I have read for ESX3 that 802.3ad configs needed to terminate in the same pSwitch unless the pSwitches had highend cross-switch ag features.
Yes, your pSwitches will need to support cross-switch 802.3ad (sometimes called switch stacking)
If 802.3ad is an option, what is generally considered best practice. Don't aggregate the links or use 802.3ad?
I usually recommend against 802.3ad unless you KNOW that you'll gain performance by using it. With four pNICs (I'm assuming 1Gbps), chances are good you're not going to be bandwidth constrained, so you're probably not going to see any "real" benefit from link aggregation. In fact, about all you're going to be gaining is complexity.
If I want to enable VLAN Tagging (802.1q) on top of this config, are ther any other special considerations for 802.3ad or not? What about 802.1q over non-aggregated links?
Nope - other than making sure your pSwitch supports .1Q - oh, be sure that all ports are configured to trunk (tunnel) all VLANs. If you have one of your pSwitch ports that doesn't allow one (or more) of your VLANs, you can wind up with a tough to troubleshoot condition where a VM can talk except when it can't 
When I talk to our network guys they see 4 pNICS and want to 802.3ad (Etherchannel) them together. If it is practical I would rather just leave the extra moving part of 802.3ad out of the picture.
Lots of networking folks still don't understand how VMware deals with multiple uplinks. First, ESX does static 802.3ad - so no LACP or other dynamic protocols supported. Load balancing is done on a per conversation basis, so you don't derive the benefits of more "intelligent" implementations. It is practical, and in many (most?) cases, I would say preferred, to just use the default load balancing algorithm (vSwitch port based) and be done with it.
-MattG
If you find this information useful, please award points for "correct" or "helpful".
Ken Cline
VMware vExpert 2009
VMware Communities User Moderator
Blogging at: http://KensVirtualReality.wordpress.com/
Scenario:
I have 4 pNICs on my ESX 4 host that I want to use for my VM Network vSwitch (Port Group). I have 2 physical switches that I want split my 4 pNIC connections across for redundancy.
Questions:
Do I need to do anything special on the pSwitch side to configure the NIC ports to handle all 4 pNICs going to a single vSwitch?
Not if you use any load balancing algorithm other than IP Hash.
What about 2 to each pSwitch?
Ditto
If I choose to trunk these links with 802.3ad (2 pNICs going to each pSwitch):
Will this require that the vSwitch is configured as IP Based Hashing or can this be the default of Port ID load balancing?
Yes - IP Hash is required when you use 802.3ad.
Does this config require a special config/feature between the pSwitches to handle the cross switch 802.3ad? I have read for ESX3 that 802.3ad configs needed to terminate in the same pSwitch unless the pSwitches had highend cross-switch ag features.
Yes, your pSwitches will need to support cross-switch 802.3ad (sometimes called switch stacking)
If 802.3ad is an option, what is generally considered best practice. Don't aggregate the links or use 802.3ad?
I usually recommend against 802.3ad unless you KNOW that you'll gain performance by using it. With four pNICs (I'm assuming 1Gbps), chances are good you're not going to be bandwidth constrained, so you're probably not going to see any "real" benefit from link aggregation. In fact, about all you're going to be gaining is complexity.
If I want to enable VLAN Tagging (802.1q) on top of this config, are ther any other special considerations for 802.3ad or not? What about 802.1q over non-aggregated links?
Nope - other than making sure your pSwitch supports .1Q - oh, be sure that all ports are configured to trunk (tunnel) all VLANs. If you have one of your pSwitch ports that doesn't allow one (or more) of your VLANs, you can wind up with a tough to troubleshoot condition where a VM can talk except when it can't
When I talk to our network guys they see 4 pNICS and want to 802.3ad (Etherchannel) them together. If it is practical I would rather just leave the extra moving part of 802.3ad out of the picture.
Lots of networking folks still don't understand how VMware deals with multiple uplinks. First, ESX does static 802.3ad - so no LACP or other dynamic protocols supported. Load balancing is done on a per conversation basis, so you don't derive the benefits of more "intelligent" implementations. It is practical, and in many (most?) cases, I would say preferred, to just use the default load balancing algorithm (vSwitch port based) and be done with it.
-MattG
If you find this information useful, please award points for "correct" or "helpful".
Ken Cline
VMware vExpert 2009
VMware Communities User Moderator
Blogging at: http://KensVirtualReality.wordpress.com/