Before designing a virtual network for the virtual machines it is very important to know the features, terms and options available in the vmware vsphere for the virtual network design. The prime components of a network design are always the switches. So I will start with the switches. The virtual switches present inside vmware vsphere have similar features to physical switches but at the same time there are some differences as well.
Some differences between physical and virtual switches :-
-> A vswitch does not use the dynamic negotiation protocol for trunk establishment. (DTP or PAgP)
-> A vswitch cannot be connected to another vswitch
-> As a vswitch is not connected to another vswitch, STP is not present in vswitches.
-> NO mac address learning as it already knows the MAC addresses of the attached VMs
-> Traffic received from one uplink is never forwarded another uplink. Hence again there is no need to run STP.
-> A vswitch also doesnt have to perform IGMP snooping as it knows the multicast address of the VMs.
Starting with the switches there are two types of switches present inside vSphere they are
Standard vSphere Virtual Switch or vSwitch or vSS and vSphere Distributed Switch or vDS or dvSwitch(Vsphere 4.1).
Both of the switches reside in vmkernel and provide traffic management for the virtual machines and the management traffic (Vmotion, iSCSi etc.). One of the major differences between the two is that the standard vritual switches vSwitches are managed independently for an individual ESXi host whereas a distributed switch is managed at cluster level. A distributed switch can have several esxi on it if they are in a single cluster.
Port Group – They can be considered as logical separation of VMKernel traffic and VM traffic.
The virtual machines have different types of network adapters. There are three different network adapters used inside virtual machines they are :-
1.) vmxnet adapter – High performance 1gbps adapter. This adapter only works when VMware tools are installed . It is also called para-virtualized driver. The adapter is mentioned as flexible in vmware properties.
2.) vlance adapter – It is a 10/100 mbps network adapter. It is compatible with most of the operating systems and the default adapter till the VMware Tools are not installed.
3.) e1000 adapter – This adapter emulates the intel e1000, it is 1GBps adapter and mostly common in 64 bit VMs.
This introduction will to understand the virtual networking better. In my future posts I will cover the networking concepts and lab in detail.