Help with clarification on UCS C220 ports

[Ess Emque]

Hi guys New to unified computing (and servers / virtualisation in general to be honest!) so sorry for the silly questions I guess. I have been trying to read as much as I can but still a bit fuzzy on a few things.

On the back of the UCS C220 that I have, there is an M port, a LAN 1, LAN 2, and then a 4 port ethernet card. What I guessed was:

M was management port for CIMC

LAN 1 & 2 were for ESXi (NIC teaming?)

So not sure what is the purpose of the 4 port ethernet card as well?

Also, on CIMC, you have the option for dedicated/shared LOM etc and I don't really understand the differences. I guessed that dedicated meant that CIMC used the M port and shared LOM meant it could use the other LAN ports? Also, do CIMC and the ESXi need to be on separate subnets?

Sorry for the silly questions, but once I get this clear in my head I think it will be easy for me,

Thank you

[padramas]

Hello,

Welcome to UCS.

C220 has two LOM ( NIC integrated into system board ) ports. In your server, you have additional PCI based NIC card that 4 ports.

Usage of these NIC ports really depends upon your application requirements. For example, if you are planning to install ESXi, you can provision these ports for ESXi management traffic, vmkernel  ( iSCSI / NFS / vmotion / FT ) traffic and for data traffic of virtual machines.

NIC mode are defined based on physical path for CIMC traffic

Dedicated mode - CIMC can be accessed only via dedicated management ( M ) port. So you need a cable connected to M port. M port is not visible to host OS.

Shared LOM - CIMC traffic flows through LOM ports that are also used for host OS traffic.

CIMC address and  ESXi vmknerel can be in same subnet or different subnet and it depends upon your network design and management network.

HTH

Padma

[Ess Emque]

Thank you very much Padma

I guess this is mostly as I thought - but still have some questions (sorry!)

If I have CIMC running in "Shared LOM" then it means I can have 1 cable connected from one of the LOM ports and can access both the CIMC and ESXi on a single cable without the need for the management cable to be connected? In this case the CIMC and ESXi can also be on the same subnet without problems? (Assuming switch with single vlan)

In the same scenario, with a flat LAN - If I wanted to use the management port, can the CIMC be connected via the management port (say on 192.168.1.1/24 and in dedicated mode) and then ESXi via LAN1 and given an address on the same subnet (e.g 192.168.1.2/24). I guess this wouldn't be a problem as it's essentially two different hosts?

Thanks so much

[padramas · Accepted solution]

Hello

If I have CIMC running in "Shared LOM" then it means I can have 1 cable connected from one of the LOM ports and can access both the CIMC and ESXi on a single cable without the need for the management cable to be connected?

Yes, single cable connected to the LOM port will provide access to CIMC and ESXi interface.

  In this case the CIMC and ESXi can also be on the same subnet without problems? (Assuming switch with single vlan)

They can be in same subnet and will not cause any issues

Padma

[Ess Emque]

You are a great help Padma. Thank you very much