VLANs and Cisco UCSM

Just a short note on using VLANs with Cisco UCSM.

First, you create the required VLANs on your upstream network switch, trunk them.
Now on the Cisco UCSM, create those VLANs under LAN Cloud with appropriate name and VLAN ID (number).
Now attach these VLANs to the vNICs (in the Service Profile Template) or vNIC Templates, as the case may be.
Then on the OS or Hypervisor, tag the VLAN to the NIC or vSwitch.

One point of caution is that if you have marked a VLAN as native in UCSM, then don’t tag it in the OS or Hypervisor. But other VLANs (non-native ones), need to be tagged.

This is what the Cisco UCSM 4.0 documentation says about Native VLANs:
“The native VLAN and the default VLAN are not the same. Native refers to VLAN traffic without an 802.1q header and can be assigned or not. The native VLAN is the only VLAN that is not tagged in a trunk, and the frames are transmitted unchanged.

You can tag everything and not use a native VLAN throughout your network, and the VLAN or devices are reachable because switches use VLAN 1 as the native by default.”

Creating a Private Network for use between 2 OSes or Hypervisors:
If you want to create a private network, say for Heartbeat or Cluster Communication Network, you can simply create a dummy VLAN on the UCSM and attach it to the appropriate vNICs. Tag it on the NIC or vSwitch. Done. Private network, now, should communicate with each other.
This way you are not required to create VLAN on the upstream switch as the traffic is going to stay internal between the 2 OS-es or Hypervisors or VMs and not going to leave the Fabric Interconnect.

Ref: https://www.cisco.com/c/en/us/td/docs/unified_computing/ucs/ucs-manager/GUI-User-Guides/Network-Mgmt/4-0/b_UCSM_Network_Mgmt_Guide_4_0/b_UCSM_Network_Mgmt_Guide_4_0_chapter_0110.html#concept_607EF16FF3AE4B53ADEA3DC0CA115A67

Apologies for writing posts very rarely. It was due to waiting for preparing the post, perfecting it etc. Going forward, will be writing posts as and when I come across an issue and it’s solution. Will format them later on as the issues and solutions need to reach faster to those in similar situations. I have realized that it takes some short time to just write the main content across.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s