VLT members os10

Hello,

in OS10, simply changing the discovery-interface range doesn’t automatically add those interfaces to the VLT port-channel. You’ll still need to manually assign the new interfaces to the port-channel used for the VLT interconnect (usually Port-channel 1000).

@DELL-Erman O​ 

this is not accurate as you can’t manually assign port-channel 1000

sw2(conf-range-eth1/1/49-1/1/52)# channel-group 
  <1-999,1001-2000>  Specify a port channel number

Oops yeah, you’re right. You can’t manually assign interfaces to Port-channel 1000 because it’s automatically managed by the system once you define the discovery-interface under the vlt-domain. That port-channel is reserved specifically for VLTi, and its membership gets auto-populated based on the interfaces listed in the discovery-interface command.

If the new interfaces aren’t showing up, make sure:

• They’re physically up and have matching settings (speed, duplex, MTU, etc.) on both switches.
• There are no config conflicts, like if they’re still part of another port-channel or have leftover config that might interfere.

@DELL-Erman O​ 

I verified everything, and the configurations match, also there is no leftover at its new setup.

When using SFS, you need to delete the SmartFabric cluster to change ports. I wanted to confirm that this is not required in full switch mode.

The only other potential issue I see is that the new ports are 100 Gb, while the current ports are 25 Gb. Could that be causing the problem?

The reference manual is vague about the requirements.

Je1000,

No, Full Switch Mode is not strictly required to configure VLT in OS10. However, whether you're operating in SFS mode or Full Switch Mode, the configuration behavior and flexibility differ significantly.

The key differences would be

Full Switch Mode

Recommended for manual VLT configuration.
Offers complete CLI control over VLT domain setup, port-channel assignments, VLANs, and spanning tree.
No restrictions from SmartFabric automation.
Ideal for custom topologies, mixed port speeds, and advanced routing.

SmartFabric Services (SFS) Mode

VLT is automatically configured as part of the SmartFabric cluster.
Port roles (e.g., server, uplink, VLTi) are assigned by the cluster.
Changing port roles often requires deleting and recreating the cluster.
Not suitable for manual VLT configuration or mixed-speed VLTi links.

The speed mismatch is a valid concern, as OS10 VLT requires that VLTi ports be identical in speed and configuration, so If one peer uses 100 Gb ports and the other uses 25 Gb, the VLTi may fail to establish or behave unpredictably.

Let me know if this helps.

@DELL-Chris H ​ 

Can you please confirm that in Full Switch Mode, changing the VLTi ports is supported?

As for the port mismatch, it’s not between switches. I only have two switches, but the working ports are 25 Gb, and I’ve now connected the 100 Gb ports. However, they’re not being discovered or automatically added to port-channel 1000

Yes changing VLTi ports is supported in Full Switch mode., to include using 100 Gb interfaces, provided the following conditions are met:
Manual configuration is required

VLTi ports are not auto-discovered.

You must configure the new 100 Gb ports as discovery interfaces in the VLT domain.

So to use 100 Gb ports (e.g., ethernet 1/1/33 and 1/1/34) as VLTi, you would need:

OS10(config)# interface range ethernet 1/1/33-1/1/34
OS10(conf-range)# no switchport
OS10(conf-range)# exit

(Leaving switchport mode enabled on VLTi ports will prevent them from being used)

OS10(config)# vlt-domain 1
OS10(conf-vlt-1)# discovery-interface ethernet 1/1/33
OS10(conf-vlt-1)# discovery-interface ethernet 1/1/34

This should cause port-channel 1000 to be automatically created and mapped to the specified interfaces.

@DELL-Chris H ​ 

this is what its set and its not working