The COVID-19 pandemic demonstrated the need for resiliency in the modern enterprise. Without systems and solutions in place to maintain operations in the face of unexpected events, a business may not survive business disruption.
When discussing resiliency, the focus is often on endpoints. Organizations need to ensure that their websites remain online, databases are accessible, and workers have access to their computers.
However, in the modern distributed enterprise, the resiliency and performance of the network is as important as that of the endpoint. The enterprise WAN has superseded the enterprise LAN, and companies need to ensure that their employees and customers can access resources that are geographically distributed at multiple sites and in the cloud.
When designing a business continuity strategy, it is important to consider network performance and redundancy and be aware of the different approaches to achieving them. Multiprotocol label switching (MPLS) performance and redundancy guarantees differ significantly from that of software-defined WAN (SD-WAN), and the wrong approach can leave an enterprise unprepared for the next “black swan”.
Different Approaches to Network Performance Redundancy
High network performance and resiliency are essential for any modern organization. The increased adoption of cloud computing, transition to remote work, and other factors have placed organizations in a position where connection speed between geographically distributed locations is essential to productivity and efficiency.
MPLS and SD-WAN offer two ways to achieve these necessary guarantees. While they can provide many of the same benefits, they do so in very different ways.
MPLS’s Dedicated Circuits
MPLS takes the approach of using dedicated circuits to offer high, guaranteed network performance. MPLS is especially well-known for its middle-mile performance. Since network traffic on MPLS circuits has dedicated links in ISP’s infrastructure and uses special network routing functionality, MPLS offers especially high middle-mile performance and resiliency.
Where MPLS starts to have issues is at the last mile. Organizations need to lease dedicated MPLS circuits, and this network bandwidth is expensive. As a result, MPLS connectivity is geographically limited, a potential issue for remote users and sites.
The cost of last-mile MPLS circuits also impacts resiliency. Purchasing and deploying redundant circuits is cost-prohibitive, meaning that an enterprise’s MPLS deployment often relies on a few links from a single carrier. A severed cable or an outage at the ISP can render the MPLS circuits completely unusable.
SD-WAN’s Optimized Routing
SD-WAN takes a different approach to network performance and resiliency than MPLS. Instead of investing in dedicated circuits, SD-WAN attempts to optimize the use of existing infrastructure, such as broadband Internet and mobile networks.
SD-WAN appliances are designed to sit at the end of an organization’s network and act as a single point of contact between the internal network and the public Internet. All outbound traffic is routed to the SD-WAN appliance, which selects a route for it based upon:
- Link Health: SD-WAN appliances constantly monitor the health and performance of the various transport media that they are connected to (i.e. broadband Internet, mobile networks, and MPLS circuits). The routes selected by an SD-WAN appliance will be designed to avoid congestion, severed links, and other issues.
- Application Requirements: Different applications have different performance and reliability requirements. SD-WAN appliances can identify the application source of traffic and route traffic accordingly. For example, limited MPLS bandwidth may be reserved for latency-sensitive Software as a Service (SaaS) applications.
- Priority Rules: Application identification can also be used to implement prioritization and other application-specific rules. For example, videoconferencing traffic may be assigned a higher priority than visits to social media websites.
SD-WAN optimize the route of all of the traffic sent to it and has very high resiliency due to its ability to route traffic over multiple transport media. If an MPLS link is down, an SD-WAN appliance can route traffic over broadband Internet or mobile networks until normal operations are restored.
The main limitation of SD-WAN is that it cannot always provide the same performance guarantees as MPLS. MPLS’s dedicated circuits work differently than broadband Internet links. While SD-WAN can optimize its use of the available media, it is limited by the capabilities of those transport media. If the slowest MPLS link is faster than the fastest broadband Internet link, then no level of optimization will allow SD-WAN to compete with MPLS (unless SD-WAN uses dedicated circuits). However, SD-WAN’s greater bandwidth and increased affordability can help to make up for this.
Pursuing the Best of Both Worlds
MPLS guarantees network performance by routing traffic over special, dedicated links but suffers from high costs and resiliency issues. SD-WAN is cheaper and more resilient but is limited by its transport infrastructure.
As network performance becomes critical to enterprise productivity, the best solution is a mix of the best of MPLS and SD-WAN. A global network of dedicated Tier-1 network links over multiple providers with SD-WAN optimization can provide unmatched network performance and resiliency.