How Not to Assign KVM IP Addresses Via Cisco UCS Manager

After a few hours poking around a newly deployed UCS cluster trying to get some basic profiles created and assigned. I realized that I had actually no idea how the KVM is actually supposed to work inside the UCS cluster. Which is funny as this was a subject that we touched on during my DCUDC class. Apparently we did not touch on it enough.

Anyway, before I get ahead of myself, lets review the gear in this cluster.

_{2 5108 chassis
7 B200 M2 blades with 2104 IOMs
2 6248s Fabric Interconnects}

Now in my network all lights out management ips (ilos, ipmi, etc) are all on one particular vlan, which for the purpose of this post we will call VLAN 100. Non application related infrastructure equipment (servers, virtual hosts) are on another vlan, which we will call VLAN 200. So when the Fabric Interconnets were deployed, I gave them each an ip address on VLAN 200. And once UCS Manager was up and running, I created a KVM ip address pool of unused ip addresses on VLAN 100. Well guess what, this is wrong.

Routing for the KVM addresses is done through the management interfaces on the Fabric Interconects, so unless you are using vlan tagging, your KVM pool must be on the same vlan as the ip addresses assigned to your Fabric Interconnects.

But wait, why is this?

I thought that I could even assign private 192.168.x.x ip addreses to the KVMs as they were only supposed to be managed via the UCS Manager, but this also incorrect.

Navigate to one of your working KVM ip addresses in a web browser and you can access the KVM of the blade outside of UCS Manager. Nice, which is how I actually expected this to work. 

Note that I find it rather dumb to have my KVM management ips and Fabric Interconnects on the same vlan as a rule, however since this is how its supposed to work I am going to have to let that one go.

Now, the fact that you can navigate to a specific KVM IP address via a web browser also makes the idea of using a pool of ip addresses silly. Would you not want to hard code the KVM ip address in the service profile so that you always know which server's console you are logging into? Dunno, I am still working on figuring that one out.

 

Comments

[M. Sean McGee]

Hello!
UCS Manager now has the ability to assign an ip address to the Service Profile also - not just the physical blade.

See "IP address for CIMC (remote KVM) added to UCS Service Profile" at this link: http://www.mseanmcgee.com/2010/12/cisco’s-stocking-stuffer-for-ucs-customers-firmware-release-1-41/

Regards,
Sean

[Chris Paquin]

Hey thanks - I was actually reading your blog the other day.

[Casper42]

Read both this post and Sean's mention of the Profile based KVM IP.

Does the Profile based KVM IP have the same limitation in that it must reside on the same VLAN as the Fabric Interconnects?

Also, if you are using the Profile based KVM IP, can you skip the hardware based one? Otherwise I would think you will run out of IPs on that VLAN twice as fast, no?