February 17, 2022
3 min read time

Varnish Controller 4.0 with Traffic Router


Today’s release of Varnish Controller 4.0 is a milestone for us at Varnish Software.

This version of our control plane integrates Traffic Router, a tool for ensuring clients fetch content from the optimal location, to get the best quality experience at all times. It offers various decision-making options for routing, so you can base it on:

Distance | Availability | Utilization | History | Tags | Random | External endpoints

Client requests will always land on the best possible cache node, guaranteeing quality of service and helping balance traffic across your Varnish CDN. Traffic Router supports both HTTP and DNS-based routing.


Controller-4.0-Traffic-Router Laptop

Why is this particular release a milestone? 

Because it brings together into one simple dashboard all the key components of a Private CDN solution. Now, from one place, you can manage and control CDN caching, configuration, monitoring, request routing and load balancing. Traffic Router unlocks operational simplicity and guarantees quality of service, but that’s not all. As an add-on service to Varnish Controller, Traffic Router extends functionality considerably:


Scaling out beyond existing capacity and extending coverage

In times of unforeseen demand and high traffic, a caching service may reach full utilization, or the headroom may be unacceptably small, leading to risks of downtime or suboptimal user experience. Short notice broadcasting changes may also see streaming services needing to handle many more visitors but without time to scale up the core network. 

Traffic Router helps scale-out and route to external endpoints, such as public CDN, when existing nodes are fully utilized. This maintains performance and uptime when scaling rapidly during traffic changes or when needing to extend CDN footprint. It’s possible (and easy) to use multiple public CDNs too.


Maintaining high availability and balancing traffic

If CDN locations are unexpectedly offline, unhealthy, overutilized or otherwise unavailable, any client requests that reach them could be dropped, lost or delayed. Clients directed to these cache nodes could receive a degraded experience, with predictable costs for quality of service and reputation. 


Traffic Router sends clients to the best Varnish node, based on the flexible rules engine. Clients get the best user experience possible by being directed to the closest, least utilized cache. They are always routed to well-functioning cache servers, so no requests hit unavailable locations and no requests get dropped. Active health checking and public CDN endpoint checks also take place to ensure cache quality.


Flexibility for working within Open Caching systems

Traffic routing is the backbone of Open Caching (OC). Traffic Router is a useful tool for implementing the OC specification for routing end-users and upstream CDNs to the best cache node within an OC system.


Controller and Traffic Router work anywhere

Traffic Router, and the Varnish CDN platform as a whole, is platform-agnostic, deployable across bare metal, cloud, containers and VMs. Traffic Router is also load balancing mechanism-agnostic and supports both HTTP and DNS-based routing.

Controller 3.0 & Traffic Router Diagram

Traffic Router sends clients to the correct Varnish edge node, which then fetches content from the correct Varnish storage node or origin.


Varnish Controller 4.0 also adds: 

  • Test-compile feature
  • Drag and drop dashboard creation
  • GeoIP Agent tagging
  • Many fixes, speed ups and UI improvements


You can find more information on the Controller 4.0 release here; and for more details on Traffic Router visit http://docs.varnish-software.com/varnish-controller/concepts/routers/.