How to enable Jumbo Frames on Cisco UCS and ESXi

This post will help you enable Jumbo frames on a Cisco UCS environment.

This post assumes a few things:

• You understand the impact of enabling Jumbo Frames


• You are running Cisco Nexus 5548 switches


• You are running Cisco UCS Fabric Interconnect firmware 2.1


• You are not using multiple QoS Systems Class Priorities (Platinum, Fold, Silver, Bronze)


• All network traffic is tagged as Best Effort within Cisco UCS


• All VNIC interfaces attached to Service Profiles are using Best Effort QoS System Class


• All VNIC adapters are attached to VNIC templates

Cisco UCS Configuration

-Login to the UCSM, Click on the LAN Tab.
-Expand LANs, & LAN Cloud.
-Click on the QoS System Class, Change the “Best-Effort” MTU to 9216.

NOTE: You need to just type in the number. It’s CANNOT be selected in the drop-down.

-On the vNIC Template or actual vNIC on the Service Profile, set the MTU value to 9000

5548 Configuration

-Login to the 5548 switch on the “A” side.
-Type the following;

system jumbomtu 9216
policy-map type network-qos jumbo
class type network-qos class-default
mtu 9216
multi-cast-optimize
exit
system qos
service-policy type network-qos jumbo
exit
copy run start

-Repeat on the “B” Side

ESX/ESXi Configuration - Enabling Jumbo Frames for all port groups or ports

You can configure the MTU value of a vDS switch so that all portgroups and ports use Jumbo Frames.

Note: Any new ports created after adjusting the setting use Jumbo Frames. Existing ports are not affected.

To configure Jumbo Frames on a vDS:

1. From vCenter Server click, click Home > Inventory > Networking.


2. Right-click the vDS and choose Edit Settings.


3. On the Properties tab, select the Advanced option.


4. Change the Maximum MTU value from the default value of 1500 to 9000. This enables Jumbo Frames on all portgroups and ports.

ESX/ESXi Configuration - Enabling Jumbo Frames on a VMkernel port from the vCenter server

To enable Jumbo Frames on a VMkernel port from vCenter Server:

1. Click Home > Hosts and Clusters > Host > Configuration > Networking.


2. Navigate to the vSphere Distributed Switch tab.


3. Click the VMkernel port (eg: vmk1)


4. Click Manage Virtual Adapters.


5. Select the vmk interface and click Edit.


6. Under the NIC settings, change the MTU value to 9000.


7. Click OK