General best practice for VLANs and domains

Question

I recently took a job at a school. This is only my second position as an IT professional. My only experience with corporate networks is in a large school district at another school. They used VLANs to separate traffic based on device type: VoIP, wireless APs, desktops etc. They had one domain with an extensive OU tree to manage AD, and all VLANs were bridged.

At my new position, the network is set up far differently. They use three different domains at each site to segregate each user and device type. One domain each for admin and teacher, classroom, and lab computers. Each domain gets a VLAN.

Is this a common implementation? I want to find out what the best practice would be, and if this can cause network performance issues.

Answer 1

You may consider the following general guidelines when implementing VLANs:

• Grouping devices by traffic patterns – Devices that communicate extensively between each other are good candidates to be grouped into a common VLAN.
• Grouping devices for security – It is often a good practice to put servers and key infrastructure in their own VLAN, isolating them from the general broadcast traffic and enabling greater protection.
• Grouping devices by traffic types – As discussed in this How To, VoIP quality is improved by isolating VoIP devices to their own VLAN. Other traffic types may also warrant their own VLAN. Traffic types include network management traffic, IP multicast traffic such as video, file and print services, email, Internet browsing, database access, shared network applications, and traffic generated by peer-to-peer applications.
• Grouping devices geographically – In a network with limited trunking, it may be beneficial to combine the devices in each location into their own VLAN.

In your case (if I got it right) looks like they are grouping VLANS by "Department" (teachers, labs, classrooms...).

Here you may find some useful information regarding network implementation on an educational environment (Chapter 3): http://www.cisco.com/c/en/us/td/docs/solutions/Enterprise/Education/SchoolsSRA_DG/SchoolsSRA-DG.pdf