14. Why Use an End-to-End Header Field?

Compared to the HTTP/2 priority scheme that uses hop-by-hop frames, the Priority header field is defined as "end-to-end".

The way a client processes a response is an attribute associated with the client generating that request rather than an attribute of the intermediary. Therefore, it is an end-to-end attribute. How these end-to-end attributes carried by the Priority header field affect prioritization ordering among responses sharing a connection is a hop-by-hop matter.

Defining the Priority header field as end-to-end is important for caching intermediaries. Such intermediaries can cache the value of the Priority header field along with the response and utilize the cached header field's value when serving the cached response, simply because the header field is defined as end-to-end rather than hop-by-hop.

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