Software-defined wide area networks

Versatile Connections

Minimal Packet Loss

With the help of WAN optimization technologies, forward error correction, and packet order correction, packet loss can be minimized over the various lines. Forward error correction is, put simply, RAID, known from the storage sector, applied to network packets. In a sequence of packets, a parity packet is added to, for example, every fifth packet. If one of the four data packets is lost, it can thus be computed from the packets received and the parity packet. This completely compensates for packet loss on the receiving side.

Packet order correction ensures that the packets are delivered in the correct order thanks to caching in a buffer, which prevents TCP re-transmissions and thus increases the reliability and the effective bandwidth of the lines. Because forward error correction ensures almost completely lossless transmission, no additional latency occurs. Other technologies in the field of WAN optimization can be used in an SD-WAN environment, but they are not necessarily assumed. Compression and deduplication, for example, increase the effective bandwidth of the connections. In some networks, 1:10 reduction rates are achieved; average reduction rates of 1:5 are not uncommon.

Autonomous Provisioning

To use such an SD-WAN in a global enterprise, two components are still missing: automatic provisioning and centralized management. All SD-WAN appliances have an automatic provisioning option. The appliances, whether virtual or physical, find their management interfaces practically by themselves, because SD-WAN appliances have access to the enterprise LANs across the Internet. The appliances then contact a cloud portal located on the manufacturer's server. Because the management solution also connects to this cloud portal, the cloud portal can supply the IP address to the appliances for centralized management. The SD-WAN products known on the market implement communication between the management solution, the appliances, and the cloud portal via HTTPS.

Centralized management provides an overview of all SD-WAN routes, the individual appliances, and all the various connected WAN routes. Latencies, data loss rates, and – if a WAN optimization technology is used – data reduction rates usually can be detected, as well. Thus, you can analyze information on the bandwidth used between locations and identify weak spots in your WAN topologies. Drilling down to individual flows across the WAN is possible for troubleshooting, which gives you full insight into the content of your enterprise WAN communications for the first time.

The appliances – at least those manufactured by Silver Peak – are maintained through templates and profiles so that a large number of locations and endpoints can be configured simply. Of course, the management solution also enables direct access to the individual components to allow for site-specific changes. Moreover, the manufacturers offer extensive reporting functionalities, so you can report on the utilization of WAN routes to enterprise management and, if necessary, apply for budget resources to make changes to the site connections.

Conclusions

SD-WAN products allow companies to reduce costs for their WAN routes while improving availability. As the administrator, you gain freedom from the underlying infrastructure while boosting visibility and control.

The Author

Julian Frede is a senior systems architect with Compatible Computer Solutions.

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