Bandwidth for Business: The New Middle Mile

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Published December 17, 2021

The Internet provides access to a global market, but for many, bandwidth and geography reduce their ability to participate. The issue historically has been connecting the last mile between the end user and the local carrier. Today’s bandwidth challenge is the middle mile: for providers of online services, scaling to serve more users is limited by the connection to the region. To achieve that global reach, does every app vendor really need to build their own backbone?


For years, Wide Area Network (WAN) connections between premises or exchanges were the norm and the exclusive domain of carriers. WAN links were dedicated physical links in the last mile, with a circuit provisioned inside the carrier network to reserve bandwidth and switch rapidly between known ingress and egress points. That provisioning is what enables the carrier to guarantee the quality of service in a network Service Level Agreement (SLA) for aspects such as: 

  • Bandwidth: the speed of the link in bits per second (bps)  
  • Latency: how long it takes for data to get from one end to the other
  • Availability: how infrequently the connection is allowed to break 

However, those guarantees and provisioning created two major disadvantages for WAN links: they were typically more expensive than simple Internet access, and many customers were unhappy with how many days (or weeks) it could take the carrier to provision the link or to make any changes. 

The prevailing connectivity model today is transit via the Internet. Historically, businesses were reluctant to trust a network that is dynamic and best-effort, rather than provisioned, but that changed with Software Defined WAN (SD-WAN). The flexibility and resiliency of the Internet, traversing multiple carriers, makes per-carrier performance guarantees infeasible, but SD-WAN sidesteps that problem with simple end-to-end measurement to select from among multiple paths and validate that they meet the company requirements. While SD-WAN was initially perceived purely as cost savings, customers quickly realized its additional value: 

  • Centralized management and automation for easy site-to-site encrypted tunnel creation 
  • Automatic error detection and correction to optimize network performance 
  • Security services in the network rather than specialized hardware onsite 

While SD-WAN provides intelligence about whether WAN is needed, it’s not an outright replacement for WAN; measuring latency and bandwidth are much different than improving those qualities.

Middle Mile and Last Mile 

Combining the strengths of SD-WAN and traditional physical WANs, middle mile delivers predictable dedicated bandwidth with modern automation to solve problems such as internet bandwidth constraints, latency limitations, or highly sensitive payloads. Middle mile conceptually acts as a virtual provider over multiple transit carriers, with high-speed switched connections provisioned between the provider’s access points. This hybrid solution combines the dynamic and flexible nature of internet delivery, the known performance characteristics of point-to-point links, and the SD-WAN advantages of agility, automation, and visibility for a unique value:

  • Predictable traffic behavior on long-haul network links between regions
  • Accelerated delivery thanks to simplified and optimized in-net architecture
  • Simple and nearly instant deployment and configuration changes

The primary disadvantage of the middle mile is that the provider’s access points are not on customer premises, so most customers must use their last-mile Internet access to connect to their closest access point.

On the last-mile side, point-to-point WAN has reemerged as a new category: WAN links from customer premises to a public cloud. Rather than providing site-to-site or Internet access, these links are typically deployed for hybrid cloud connectivity, allowing cross-consumption of data and services between customer resources in the public cloud and in their data centers. While such a connection could be—and often is—delivered via VPN, there are solid benefits to a dedicated WAN link:

  • Predictable latency and bandwidth
  • Private transit so the traffic never traverses the Internet
  • Policy mapping from cloud resources to local network VLANs and subnets

While these factors are useful for capacity monitoring and planning in traditional IT, they become especially important in app-to-app networking connections for troubleshooting and application performance management.

Linking the Last Mile to the Cloud

F5 Volterra Global Network is a multi-terabit multi-cloud middle mile service, with Volterra PrivateLink as an optional last mile WAN link. On its own, the Global Network provides private transit just like middle mile, but also peers directly with every major cloud and popular SaaS. When the Global Network is deployed with PrivateLink, it creates several unique possibilities:

  • Dedicated WAN to all major clouds and popular SaaS in a single link
  • Private transit end-to-end among all sites using PrivateLink
  • Single central control for all network, security, sites, and cloud

Whether customers are looking for a WAN alternative, an SD-WAN with a private network, or hybrid cloud to integrate data centers into their multi-cloud architectures, PrivateLink and the Volterra Global Network provide an easy, predictable, and agile solution.

Bandwidth for Tomorrow’s Services

As F5 Volterra provides solutions to move customers forward into multi-cloud, we continue to be excited at the new use cases unlocked with the delivery of bandwidth and connectivity. Customers are beginning to use the Global Network both for priority transit on undersea cables and as a virtual corporate backbone. When combined with PrivateLink, customers can be disconnected from the Internet yet still connect to public cloud and SaaS, or simply leverage the unified last mile and middle mile for SaaS acceleration. Volterra PrivateLink and the Global Network combine the best of modern middle mile and last mile to solve the problems of today’s global application delivery and pave the way the in-net services of tomorrow. 

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