Designing a multi-site WAN that can support voice, video, data, and LAN traffic requires a careful inclusion of company goals. You’ll also need to consider emerging technologies as well as ever-changing security needs and network throughput.
The first step is to consider your enterprise and its goals, including:
- Planned applications
- Connectivity to outside entities (suppliers, customers, and stakeholders)
- Local and remote access requirements
- Competitive considerations
These goals will be largely influenced by whether you intend to build a new network from scratch, update an existing network, or integrate your network with other networks.
The next step is to conduct a WAN investigation. Assuming you have an existing network, you should continue the process by creating an inventory of the network with identification of the circuits and hardware, software supporting the network, and all network-related costs. Measure network performance in terms of throughput, dropped packets, and latency to determine your baseline.
If you’re creating a multi-site WAN from a combination of fixed private lines and virtual private networks (VPNs), you’ll need a WAN designed for traffic generated at each network node plus remote-user and inter-node channel traffic. Once these traffic patterns are identified, the design of the network can be initiated.
Next, you’ll need to engage in discovery, which identifies each of the components residing on the network, often through software that can locate and describe all devices on the network. Performance analysis will then help you examine how the network is working in areas such as bandwidth, throughput, and latency. This can be done using a network analyzer.
For most multi-site WAN deployments, the design may be best left to experts. Consider utilizing a managed services provider to design, install, and monitor network performance once the installation is complete.
It’s also critical to consider the impact of placing a new application on your network. With regard to your WAN resources, keep the following in mind:
- Latency: It can take a long time for data to be transmitted across a WAN, so include protocols that require receivers to acknowledge delivery of data so you can get an accurate measurement of travel time.
- Packet Loss: Even in a well-designed multi-site WAN, you may lose packets due to errors or the intentional removal of certain traffic to maintain performance levels.
- Retransmission: Lost packets in a reliable network will be retransmitted, but this introduces delays from resending as well as a delay in waiting for the data to be received in the correct order.
- Throughput: This refers to the amount of traffic a given network can carry and is usually expressed in terms such as megabits per second.
Additional factors can impact WAN performance, such as compression, encryption, and network signaling.
WAN capacity planning should be performed before network installation as well as on a relatively regular basis. The following steps offer a methodology for capacity planning:
- Gain a clear understanding of network activities, including voice communications, email, and remote access.
- Examine service and usage requirements.
- Assess network performance with data from endpoints, switches, and routers.
- Review performance audit reports.
- Evaluate bandwidth demand versus infrastructure support.
- Determine the type and number of devices the network will support in the future.
- Analyze present network configurations.
- Determine the total amount of bandwidth required, and evaluate the type of circuits needed to support traffic.
- Analyze network redundancy requirements and their impact on capacity.
- Test and validate multi-site WAN to measure how traffic generators perform with network design software.
Finally, to adequately support bandwidth requirements, it’s important to keep an eye on emerging opportunities. Consider the following factors:
- Number of users, both current and potential, consuming network resources
- Network activities, including email, audio and video, file transfers, and applications that support data transfers
- Devices used on the network
- Expectations for performance and speed
- The frequency of data being downloaded and uploaded
- Security concerns, including data encryption