Last Mile Constraints

Last Mile Constraints

As more businesses require 24/7 uptime of their networks, they can’t afford to “put all their eggs in one basket.” Even MPLS with its vaunted “5 9s” SLA, has struggled with last-mile availability. SD-WAN offers a way forward that significantly improves last-mile uptime without appreciably increasing costs.

Early Attempts To Solve The Problem

Initial efforts to solve the problems and limitations of the last mile had limited success. To improve overall site availability, network managers would pair an MPLS connection with a backup Internet connection, effectively wasting the capacity of the Internet backup. A failover also meant all the current sessions would be lost and typically the failover process and timeframe was less than ideal.

Another early attempt was link-bonding which aggregates multiple last-mile transport services. This improved last mile bandwidth and redundancy but didn’t create any benefits for the middle mile bandwidth. Functioning at the link layer, link-bonding is not itself software-defined networking, but the concept of combining multiple transports paved the way for SD-WAN that has proven itself to be a solution for today’s digital transformation

How The Problem is Solved Today

Building off the concept from link-bonding to combine multiple transports and transport types, SD-WAN improves on the concept by moving the functionality up the stack. SD-WAN aggregates last-mile services, representing them as a single pipe to the application. The SD-WAN is responsible for compensating for differences in line quality, prioritizing access to the services and addressing other issues when aggregating different types of lines.

With Cato, we optimize the last mile using several techniques such as policy-based routing, hybrid WAN support, active/active links, packet loss mitigation, and QoS (upstream and downstream). Cato is able to optimize traffic on the last mile, but also on the middle mile which provides end-to-end optimization to maximize throughput on the entire path. The need for high availability, high bandwidth, and performance is achieved by enabling customers to prioritize traffic by application type and link quality, and dynamically assign the most appropriate link to an application.

The Cato Socket is a zero-touch SD-WAN device deployed at physical locations. Cato Socket uses multiple Internet links in an active/active configuration to maximize capacity, supports 4G/LTE link for failover, and applies the respective traffic optimizations and packet-loss elimination algorithms.

Willem-Jan Herckenrath, Manager ICT for Alewijnse, describes how Cato Cloud addressed his company’s network requirements with a single platform: “We successfully replaced our MPLS last-mile links with Internet links while maintaining the quality of our high definition video conferencing system and our Citrix platform for 2D and 3D CAD across the company.”

SD-WAN Leads The Way

The features and capabilities of Cato Cloud empower organizations to break free from the constraints of MPLS and Internet-based connectivity last mile challenges and opens up possibilities for improved availability, agility, security, and visibility. Bandwidth hungry applications and migrations to the Cloud have created a WAN transformation revolution with SD-WAN leading the way.


  • What is SD-WAN?

    Software-defined Wide Area Network (SD-WAN) devices sit in company locations and form an encrypted overlay between themselves across any underlying transport service including MPLS, LTE, and broadband Internet services.

  • What are the benefits of SD-WAN?

    Reduced Bandwidth Costs: MPLS bandwidth is expensive. On a “dollar per bit” basis, MPLS is significantly higher than public Internet bandwidth. Exactly how much more expensive will depend on a number of variables, not the least of which is location. However, the costs of MPLS aren’t just a result of significantly higher bandwidth charges. Provisioning an MPLS link often takes weeks or months, while a comparable SD-WAN deployment can often be completed in days. In business, time is money, and removing the WAN as a bottleneck can be a huge competitive advantage.
    Reliable Network Across the Unreliable Internet: The ability to connect locations with multiple data services running in active/active configurations. Sub-second network failover allows sessions to move to new transports in the event of downtime without disrupting the application.
    Secure Communications: Encrypted connectivity secures traffic in transit across any transport.
    Bandwidth on Demand: The capability to immediately scale bandwidth up or down, so you can ensure that critical applications receive the bandwidth they need when they need it.
    Immediate Site Activation: Bring up a new office in minutes, instead of weeks and months that it takes with MPLS. SD-WAN nodes configure themselves and can use 4G/LTE for instant deployment.

  • What are the key trends driving SD-WAN adoption?

    Enterprises built their networks using legacy carrier services, such a managed MPLS service. These services are expensive, require weeks to months to activate sits, and require waiting for the service provider to make even the simplest of changes.
    SD-WAN offers an escape from that bringing agility and cost efficiencies to IT networking. The SD-WAN connects locations with several Internet connections, aggregating them together with an encrypted overlay. Policies, application-aware routing, and dynamic link assessment in the overlay allow for the optimum use of the underlying Internet connections.
    Ultimately, SD-WAN delivers the right performance and uptime characteristics by taking advantage of the inexpensive public Internet with the security and availability needed by the enterprise.

  • What are the limitations of SD-WAN?

    Lack of a global backbone: SD-WAN appliances sit atop the underlying network infrastructure. This means the need for a performant and reliable network backbone is left unaddressed by SD-WAN appliances alone.
    Lack of advanced security features: SD-WAN appliances help address many modern networking use cases, but don’t help with security requirements. As a result, enterprises often need to manage a patchwork of security and networking appliances from different vendors (Like CASBs) to meet their needs. This in turn leads to increased network cost and complexity as each appliance must be sourced, provisioned, and managed by in-house IT or an MSP.
    No support for the mobile workforce: By design, SD-WAN appliances are built for site-to-site connectivity. Securely connecting mobile users is left unaddressed by SD-WAN appliances.