Cisco Support Community
Showing results for 
Search instead for 
Did you mean: 

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. If you'd prefer to explore, try our test area to get started. And see here for current known issues.

New Member

Cisco UCS -Network, etc.

Hi, Cisco Geeks:

I need your expert expertise on the following:

1. Understand that Cisco UCS firmware version 2.0(##) supports disjoint Layer 2 network, etc.


So do I have to change the FI to Switch Mode FIRST?


For LAN & SAN setup and maybe all other configurations, IS THERE ANY DIFFERENCES from End-Host Mode at all?




Anything to WATCH OUT for within UCS and VMware environment WRT configuration, etc?

In my life with Cisco UCS, this is my first dive into Switch Mode, so I am ...



P.S. Please feed me as much as possible, caveats, best practices, recommendations, etc.


Cisco UCS -Network, etc.


Now you know we prefer to be called Gurus than Geeks right? lol


1. No,  switchmode was the only workaround to support disjoint layer 2 in previous versions.  In 2.0 we have built in Disjoint Layer 2 support for EHM (End Host Mode).  There is a LAN Uplink Manage wizard now where you can assign certain VLANs to certain uplinks.  By default all systems operate in the usually way - all VLANs allowed on all uplinks unless explicitly configured otherwise.  Each VLAN now has it's own Designated Receiver interface for incoming MCast & BCast traffic (previousl it was one DR for all).

2.  Yes.  Switch mode runs STP, so links will be blocked if you have multiple uplinks.  In EHM there is no spanning tree as pinning is used to ensure host traffic never gets sourced out of more than one interface.   Watch Brad's which explains switch vs. EHM.   Keep in mind this is pre-2.0, but the conecepts other than Disjoint L2 support for EHM, all still apply.

3.  Yes, switch  mode is 100% supported by TAC.  My preference is unless you have a dire need for Switch mode, stick with EHM.  With Disjoint L2 support there should be few & far between reasons to use switch mode.  ** Keep in mind switching between Switch mode & EHM is disruptive.  Both switches reboot and you will have to apply the appropriate configuration.  You will need a maintenance window to convert to/from.

4.  Normally the decision to change between switch & EHM is during your intial deployment.  But for customers wanting to change now with the Disjoint L2 support now, it will be a considerable task - not difficult, just needs to be properly planned.    My team is going to run through some basic procedures & tests on changing over with a production system, and draft up a guide or video regarding it.  I'll post it to CSC as soon as we're done.   Brad Hedlund has a bunch of other great video's on UCS & networking operations.  I'd suggest you have a watch through his series so you're 100% clear on the differences in functionality.

If you have any other questions, let me know.



Cisco Employee

Re: Cisco UCS -Network, etc.

In 2.0 end host mode supports disjoint L2 networks.

There are a number of links that detail this and answer most of your questions.

There are also a number of blogs that do a great job of covering these topics. This one also has detailed video to boot.

Sent from Cisco Technical Support iPhone App