Wooo-weee. Aren’t there a lot of settings and options on both Distributed Switch and the Portgroup. It can feel a bit daunting if its the first time you have looked, or if like me, you haven’t looked at them in a while. So many knobs, which I know to twiddlers everywhere are so appealing – like a big red button that says “Do not press this button”. You just can’t help yourself!
So I’m going to have spread this content over a much longer series of posts than I’d originally intended – but I think that’s better than one monster post that covers absolutely everything. In this first post on the settings of Distributed Switch, I’m focusing just on the Distributed Switch itself. Just the topology, MTU, CDP/LLDP side of the house – subsequent posts will look at:
- Migrating to Enhanced LACP
- Private VLAN
- NetFlow
- Port Mirroring
- Health Check
- Using Network I/O Controls and Network Resource Pools
and then (deep breathe, I will look at the setting on a Distributed Portgroup)
The Distributed Switch offers up a whole host of advanced settings applicable to the Switch and the portgroup. Not all of these settings will be applicable, important or supportable in your deployment. However, we have chosen to cover these in as much detail as possible – highlighting the options that appear to be most commonly required in most environments.
Topology
The topology view is a good way to get an overhead view on the Distributed Configuration. He was can see the three distributed portgroups; the IP addresses used by the FT VMkernel portgroup; The physical NICs associated with the hosts and the UpLink container. The small (i) information icon allows you to view the settings on each component.
Properties
The general properties options allow you to:
- Rename the Distributed vSwitch
- Decrease/Increase the number of UpLink contains, as well as rename them
- Enable/Disable Network IO Control (Enabled by default)
- Set a description
The Advanced propeties options allow you to:
- Set the MTU size for Jumbo Frames
- Configure the Cisco Discovery Protocol settings, and switch to Link Layer Discovery Protocol
- Set a name and contact details for the Administrator
The MTU value is applied to all communications passing to/from the Distributed Switch – and its important all paths in the communication flow are configured for the correct MTU size. If the MTU size impact on a virtual machine portgroup the MTU size should be adjusted within the guest operating system to a matching size. This is to aviod a scenario called fragmentation. If a 9000 MTU ethernet packet encounters a 1500 system then the packet will be split into 6×1500 packets which will actually reduce performance, and increase the overhead on the device/system that carries out the fragmentation.
Assuming your physical switch supports Cisco Discovery Protocol (CPD) the support can be adjust to listen/advertise/both. Listen enables the vSphere Administrator to query and return information from the physical switch – this can be useful in diagnosing configuration mismatches. Likewise Advertise allows the Cisco administrator to query the Distributed Switch as if it was a physical switch. Bothallows for a combination of Listen/Advertise.
CDP is available for both Standard and Distributed Switches, but Link Layer Discovery Protocol (LLDP) is only available on version 5.0 Distributed Switches or higher. Assuming the physical switch supports one of these protocols, then you should see information in the (i) icon on a physical adapter like so:
