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Re: Network failover not working with ESXi5, hp Virtual Connect

 
Mike O.
Regular Advisor

Re: Network failover not working with ESXi5, hp Virtual Connect


@Psychonaut wrote:
I've got 12 servers running with Smartlink and "link status" - works great.

Just curious, are you using the uplink sets that span the interconnect modules, with active/standby ports?  That seems to be the configuration in the cookbook that says to not use smartlink.

 

I'd just really like to know why HP specifically says to "NOT" enable smartlink in that configuration...
Mike O.

Psychonaut
Respected Contributor

Re: Network failover not working with ESXi5, hp Virtual Connect

My uplink sets are Active/Active, so my setup is along the lines of 1:6 in the Cookbook. I looked through 1:5 and read that "NOT" statement, I don't understand it either. They word it like the system will be fine because you have other "Available" uplinks. But that doesn't help because the OS doesnтАЩt know the link is down. From other discussions and research IтАЩve done IтАЩve always been under the impression that unless you have a really good reason Smartlink should always be enabled. That way situations like that are avoided.

Perhaps one of the authors of that document is out there and can explain the reasoning.
Steven McLean
Advisor

Re: Network failover not working with ESXi5, hp Virtual Connect

Mike O/All,

 

IтАЩve read through your issue and Hongjun is correct in stating that Link State should be used with VMware now and that at the time that VC Cookbook was written, Link State was not supported.  That is no longer the case and Link State should be used.

 

As for whether SmartLink should or shouldnтАЩt be enable depends on how the VC networks are implemented.

The purpose of SmartLink is to turn OFF server downlinks that are connected to networks associated with uplinks that have become disconnected or failed.  Take a look at the examples below;

 

In Scenario 1:5, which is an Active/Standby design, when ALL links on Bay 1 are disabled or cables unplugged Virtual Connect will enable the STBY links on Bay 2 and fail all traffic over to the now active links on Bay 2.  The server will not realize the fail-over occurred, the internal stacking link will be used for Bay 1 NIC traffic.  This is the behavior we want in an A/S network design.

 

In Scenario 1:5, if we enable SmartLink, the only time it will do anything, would in the case of ALL uplinks going down.  For example, if ALL uplinks in this scenario connect to the same switch, and the switch failed, all uplinks links with be disconnected and we would lose external communications, but SmartLink would also shut down ALL connected downlinks, disconnecting ALL server NICs (both Bays) and even server to server communications within the enclosure would be lost.  This is why NOT to use SmartLink in an A/S VC config.

 

In Scenario 1:6, which is an Active/Active design, when ALL links on Bay 1 are disabled or cables unplugged ALL downlinks connected to those networks are shut down, this causes the server NIC to go offline forcing NIC teaming or the vSwitch to move all load to the remaining active NIC.  This is the behavior we want in an A/A network design.

 

I wrote that VC Cookbook and, other that Link State now being supported, thatтАЩs what I was thinking and what I meant by recommending Smart Link NOT to be used in Scenario 1:5 and why is should be used in 1:6.

 

As for your concern;

 

IтАЩve reviewed your VC config, this config is actually a merge of scenarios 1:5 and 1:6 and I would consider your design to be Active/Active, not A/S.  What I mean by this is that you have TWO SUS, each containing half the serverтАЩs NICs, which make this an A/A design.  The fact that you also have an additional pair of STBY links on each SUS, makes each SUS A/S, but the overall design is still A/A from the server perspective.  In this case, Link State and Smart Link should be used.

 

I would enable Smart Link and Link State and re-test.  All should be fine.

Psychonaut
Respected Contributor

Re: Network failover not working with ESXi5, hp Virtual Connect

Steven,

Thanks for hopping on and sharing.