How Many VMware Servers Do I Need?

If you are using the topologies designed to support Cisco Networking Academy^® content, please refer to the table below. The number of VMware servers and memory requirements vary based on the lab topologies and number of pods you plan to implement.

Step 1. Carefully study the lab topologies and determine the number of virtual switches and virtual machines required by each pod. The requirements for each pod shown below assume that you are implementing all PCs supported by the pod.

Please Note: The topologies listed here are the only ones from the collection of topologies designed for Cisco Networking Academy content that support virtual machines.

Topology	Maximum Virtual Switches (VMnet)	Maximum Virtual Machines
	3	3
	5 required, 2 optional	5 required, 2 optional
	4	5
	4	4
	3	4
	5	7
	3	4
	3	3
	3	5
	5	7

We recommend no more than 10 to 12 virtual machines per server. Each virtual machine uses CPU cycles and memory on the server. As a simple rule of thumb, divide the processor clock speed by the number of virtual machines to determine the speed of each virtual machine in a heavily loaded environment (i.e. all pods are running at the same time and users are working on the PCs). For example, a 3GHz processor could run 10 virtual machines at 300MHz each. This does not account for overhead on the host operating system.

Step 2. Add up the number of virtual switches and virtual machines used by each pod you are implementing. For example:

Pod Name	Type	Virtual Switches	Virtual Machines
POD 1	Basic Router Pod Version 2	3	4
POD 2	Basic Router Pod Version 2	3	4
POD 3	Basic Router Pod Version 2	3	4
POD 4	Basic Router Pod Version 1	0 (n/a)	0 (n/a)
POD 5	Basic Switch Pod Version 2	3	3
POD 6	Network Security Pod (2.0)	5	7
Total		17	22

Step 3. Assign each pod that supports PCs to a VMware server.

In step, we determined that 17 virtual switches are required. Since you can have up 10 virtual switches per server, you would need at least 2 VMware servers for this implementation. Server 1 could accommodate POD1, POD2, and POD3. Server 2 could accommodate POD5 and POD6. Note, POD4 does not support PCs and uses no VMware resources.

VMware Server #1

Pod Name	Type	Virtual Switches	Virtual Machines
POD 1	Basic Router Pod Version 2	3	4
POD 2	Basic Router Pod Version 2	3	4
POD 3	Basic Router Pod Version 2	3	4
Total		9	12

VMware Server #2

Pod Name	Type	Virtual Switches	Virtual Machines
POD 5	Basic Switch Pod Version 2	3	3
POD 6	Network Security Pod (2.0)	5	7
Total		8	10

Step 4. Based on the pod type and curriculum requirements, determine which guest operating system you will use on each virtual machine. Tabulate the operating system and memory requirements for the host operating system and virtual machines. You should allocate the same amount of memory as you would if standing up a real PC. The following would represent typical choices for VMware Server 1 in the previous example.

VMware Server #1

Pod	PC Name	Operating System	Memory (MB)
n/a	VMware Host O/S	Windows Server 2003	512
POD 1	PC1a	Windows XP	128
POD 1	PC1b	Windows XP	128
POD 1	PC2	Windows XP	128
POD 1	PC3	Windows XP	128
POD 2	PC1a	Windows XP	128
POD 2	PC1b	Windows XP	128
POD 2	PC2	Windows XP	128
POD 2	PC3	Windows XP	128
POD 3	PC1a	Windows XP	128
POD 3	PC1b	Windows XP	128
POD 3	PC2	Windows XP	128
POD 3	PC3	Windows XP	128
Total			2048 (2GB)

VMware Server #2

Pod	PC Name	Operating System	Memory (MB)
n/a	VMware Host O/S	Windows Server 2003	512
POD 5	PC1a	Windows XP	128
POD 5	PC2	Windows XP	128
POD 5	PC3	Windows XP	128
POD 6	PC1	Windows XP	128
POD 6	IS1	Windows 2000 Server	256
POD 6	DMZ1	Linux	64
POD 6	BB	Windows 2000 Server	256
POD 6	PC2	Windows XP	128
POD 6	IS2	Windows 2000 Server	256
POD 6	DMZ2	Linux	64
Total			2048 (2GB)