RFC 6874, "Representing IPv6 Zone Identifiers in Address Literals and Uniform Resource Identifiers", February 2013Source of RFC: 6man (int)
Errata ID: 3631
Publication Format(s) : TEXT
Reported By: Michael Sweet
Date Reported: 2013-05-22
Rejected by: Brian Haberman
Date Rejected: 2013-05-23
Section 4 says:
An HTTP client, proxy, or other intermediary MUST remove any ZoneID attached to an outgoing URI, as it has only local significance at the sending host.
It should say:
An HTTP client, proxy, or other intermediary MUST retain any ZoneID attached to an outgoing URI, as it will be the only way for an HTTP server to return a URI containing a link-local address that can subsequently be used by the HTTP client.
The original advice ignores a very real issue: HTTP Servers that generate URIs from the client's Host: need to include the Client's zoneid in order for the link local address to be usable/routable.
The zoneid is a strictly internal value that is not shared between devices.