Consider a typical network topology that utilizes MPLS, Multiprotocol Label Switching, for primary voice and data connectivity between the data center and branch offices, and site-to-site VPN as a backup. This approach is certainly functional, but failover depends on manual route changes or additional equipment to handle them dynamically, bandwidth is limited to the active connection (typically the MPLS connection), and the standby connection (typically the VPN) is unused nearly all the time.
With NetScaler SD-WAN, we can improve this architecture by deploying devices at each location and using them to establish a single virtual path consisting of both the MPLS and Internet circuits, with support for additional circuits, including LTE. This approach provides the following key benefits:
- Bandwidth aggregation and intelligent load balancing – SD-WAN combines the MPLS and Internet paths to present a single, larger virtual path. Sub-second measurements are taken bi-directionally for each available path in terms of available bandwidth, packet loss, and jitter, and traffic is sent along the best available path at a particular moment in time. This determination is made on a per-packet basis.
- Quality of Service – SD-WAN recognizes three high-level classes of service–real-time, interactive, and bulk–with the ability to define sub-classes within each. For real time (VOIP is a good example) every packet is duplicated and sent to the destination along each available path. Whichever arrives first is processed and all others are disregarded. Thus VOIP quality improves. In addition, SD-WAN automatically categorizes various types of Citrix HDX traffic.
- Reduction of branch office equipment – SD-WAN can potentially eliminate the need for VPN endpoints by establishing secure links between appliances, the need for firewalls by providing deep packet inspection relative to inbound traffic, the need for web content filtering devices by sending outbound traffic to cloud web gateways like Cisco Umbrella (formerly OpenDNS) and ZScaler, and routers to handle OSPF by aggregating and load balancing multiple circuits as described above.
As you can see, SD-WAN can simplify branch office deployments, increase bandwidth and resiliency, and improve the end-user experience. For a quick and entertaining look at SD-WAN in action, check out this video.