vSwitch also called as virtual switch is a software construct implemented in VMkernel. All network communication internal or external must be defined using vSwitch.VM uses vSwitch to communicate with one another on same or different host.VMkernel access IP stack using vSwitch. Service console uses vSwitch for remote management of the esx host.
You can create maximum of 248 vSwitch on single host.On one side of vSwitch there are port groups that connects to virtual machines. Each port on vSwitch is member of Single port group. The default number of logical port group for a vSwitch is 56 but you can increased that number to 4088. On other side are uplink which connect to physical nics of the host.
The callout icon next to port or port group display port group properties. Call out icon next to physical nics displays Cisco Discovery protocol information. CDP provides information about physical switch port the vSwitch is connected. Also additional information like Switch software version, Port ID, Port Speed/Duplex setting and timeout details.
vNetwork Distributed switch exist across the datacenter. Biggest advantage of vDS is the configuration is consistent across the datacenter.There is some configuration which is specific to host and needs to be configured per host. VMkernel,Service console ports needs to be configured on each host individually. Also uplinks are specific to each host and needs to be managed at host level.
Benefits of vDS
1. Private VLAN. Allows you to provide any VLAN ID in the private network without having to worry about duplicate VLAN ID across the network
2. Two way traffic shaping
3. Consistent network configuration at DC level
4.Network vMotion, this implicitly covers 3rd Party switch, inline IDS and firewall as network state is transferred across the host now.
5. vNetwork appliance API (e.g. Nexus1000)
You can create vDS at cluster or datacenter level
To enable jumbo frames on vDS set maximum transmission unit to 9000. To take full advantage of jumbo frame, it should be enabled end-to-end i.e. at vDS,Physical switch and VM level. To enable Jumbo frames in VM, install vmware tools, select network adapter either vmxnet3, enhanced vmxnet, or e1000 virtual device.However Jumbo frames are not supported in ESXi vmkernel stack but is supported in guest OS.