Tag Archives: vswitch

What you can learn from Networking for VMware Admins


It was not so long ago when I was searching for good resource that would uncover what is happening at the hypervisor level from network point of view and how it all clicks together to provider connectivity to ever increasing number of virtual machines. I am happy to say that I have found that resource. It is called Networking for VMware Administrators by Chris Wahl and Steve Pantol.

Networking-for-VMware-Administrators 1

The book starts by discussing the very foundation of networking, what networks is and what benefits it provides. Continuing with with common models and protocol stacks like ISO OSI and TCP/IP and the concepts of layering.

Comparing ISO OSI to TCP/IP

Comparing ISO OSI to TCP/IP

Diving more deeply into the individual layers authors start with physical layer. Ethernet technology is explained in great detail as well as common physical connectivity options like copper or fiber. You will also gain some knowledge about most used network connectors such as RJ-45 and modules like older GBIC or SFP.

10Gbps Twinax Cable used for short interconnections

10Gbps Twinax Cable used for short connections

The chapters build on top of each other and after the foundation and physical network properties next chapter covers data-link operations in great detail. You learn about switching and common network challenges like preventing network loops with spanning tree or increasing network through put by utilizing link aggregation technologies.

Another layer that could not be forgotten is Layer 3 or Network layer. In this chapter IP addressing and routing is explained in detail. Other common services such as automatic address configuration thought DHCP or name resolution with DNS are well touched giving you as a reader better overall perspective.

With the foundation lied down in first 5 chapters the book continues to touch popular converged network infrastructures. Concept of stateless computing from Cisco is explained – the Unified Computing System as well as the HP’s Blade Chassis C7000. Both are compared to give you better insight on one over the other.

Cisco Unified Computing System

Cisco Unified Computing System

The true discussion on virtual networking begins with Chapter 7: How Virtual Switching Differs from Physical Switching. This is an excellent entry point chapter, which describes similarities and differences between both. It touches on common virtual vSwitch terms such as virtual machines’s NIC cards (vNIC), Port-Group, physical uplinks (pNIC), VM kernel ports (vmk) and generally how does the virtual architecture fits with physical.

vSwitch Architecture

vSwitch Architecture


vSwitch Forwarding Logic

Better yet, this chapter outlines various configuration options on vSwitch like number of uplinks, MTU and Security Settings. Last but not least trunking and VLAN tagging options are explained.

Chapter 9 focus on vSphere Distributed Switch which is commonly found in enterprise environments. It explains how it differs from Standard vSwitch in control and data plane operations. And elaborates on many extra features it provides. You can expect to gain knowledge on link discovery protocols CDP and LLDP, exporting traffic flows with NetFlow, monitoring traffic in virtual environment using Port Mirroring, segmenting traffic using VLANs and Private VLANs and finally Load Based teaming and Network IO Control for intelligent traffic management.

After you gain this strong foundation, you are free to enter to realm of third party virtual switch. Cisco Nexus 1000V is the topic of next chapter. Authors explain the reasons why you might consider using this third party switch from Cisco in your environment. It touches on core architecture concepts like Virtual Supervisor Module (VSM) and Virtual Ethernet Module (VEM) and various modes of deployment options.

Nexus 1000V deployment options

Nexus 1000V deployment options

If you are more practical type of person, you will definitely like the lab scenarios that authors put together. A step by stem approach is outlined how to build a basic vSphere environment using Cisco UCS as main computing platform. In later chapters you will also discover how to migrate workloads from standard virtual switch to distributed virtual switch without causing downtime.

After discussing general networking technologies with relevant examples, Chapter 14 moves our direction toward IP based storage, starting with iSCSI. General uses cases are explained as well the idea of initiators and targets. Best practices for setting up iSCSI storage adapters are also well explained giving you good confidence when planning in production environment.

The storage topics are then closed by discussing NFS based storage and its uses cases. I especially like the right depth of topics around storage. Practical demonstration at the end of the chapter is also a huge benefit to better put things together.

The next to last chapter deals with additional vSwitch design options, showing many different scenarios with or without IP based storage in place and using 1 Gbps or 10 Gbps network adapters.

One of many vSwitch design options

One of many vSwitch design options

Finally, the last chapter discusses additional design options when dealing with heavy load vMotion migrations. You will learn how to design multiple VM kernel adapters for moving workloads around in case you need to. Network IO Control is also revisited in relation of egress traffic shaping and protecting v host from traffic overload, in case of multiple hosts decide to migrate loads onto same destination hypervisor.

Although I am primarily a network guy I must admin I enjoyed this well written book from the first page to last. It gave exactly what I was looking for, a good foundation of vSphere networking which is the base for advanced technologies like virtual overlays with VXLAN.