Definition and Scope
The middle mile is specifically defined as the segment that shepherds traffic between the local access collocation facility and the cloud service provider network.
This sits between the "last mile" (connecting the office/branch to the nearest collocation facility) and the "first mile" (the cloud provider or other destination network). While often focused on cloud access, the middle mile is also critical for accessing legacy applications hosted in corporate data centers.
Driven by Cloud Transition and Fragmentation
The emergence of the middle mile as a key issue is largely driven by the transition of enterprise networks towards the cloud, flipping the network topology where the cloud is now central.
The SD-WAN trend has enabled enterprises to fragment their network sourcing, buying edge connectivity from local providers rather than global telcos. This fragmentation at the edge opens up the possibility to find better options for the middle piece.
Diverse Solutions and Shifting Accountability
There's a variety of approaches to the middle mile beyond traditional Tier 1 providers. These include packaged "network as a service" offerings and do-it-yourself SDN solutions offering virtual circuits and flexible bandwidth.
Cloud providers are also emerging players. However, with increased reliance on the internet and multiple providers, a significant challenge is the fragmented accountability for performance issues, as there isn't a single entity responsible for the end-to-end path.
Enterprises are increasingly addressing potential problems through engineering diversity, such as deploying multiple middle miles from different providers, rather than relying on traditional service level agreements (SLAs).
