Origin shield cache

Most popular media delivery workflows requires down stream servers acting as Origin shield caches. This type of configuration has become recommended method to ensure performance guarantees in media distribution, and to provide the highest possible Quality of Experience (QoE) to end users.

An origin shield cache sits directly in front of Unified Origin. An intermediate server such as a HTTP proxy, a CDN, an edge server or even a media player connects to the shield cache, rather than directly to the origin.

The origin shield cache can be configured based on different media delivery use cases and requirements. In this document we present some of the most popular use cases using an origin shield cache and Unified Origin. We explain each use case and we provide an example configuration using the most popular HTTP proxy servers.

Use case support per proxy server (Apache, Nginx, Varnish)

The following table provides some of the most popular Proxy servers that can be configured as an origin shield cache: Apache, Nginx, and Varnish Cache. The table indicates the general use case of an origin shield cache and its support in each web server.

X: it fully supports the feature.
TBD: requires more testing.
No value indicates no support for it.
Other value indicates the partial support.

#	Origin shield use case	Apache	Nginx	Varnish
1	Decrease upstream traffic		X	X
2	HTTP response headers	X	X	X
3	Prefetching of content	TBD	X	X
4	Handle upstream server's limited lifetime	X	X	X
5	HTTP response codes	X	X	X
6	Content aware key caching	URI	URL	URL/Hash
7	Mitigate malicious requests	X	X	X
8	Cache invalidation/purge		X	X
9	Redundant origin shield cache	TBD	TBD	X

Load testing 

For load testing other tools can be used, varying from Apache Bench (AB) to wrk to more elaborate setups like for instance the NBMP testbed.