| The Min-Expires header field conveys the minimum refresh interval supported
for soft-state elements managed by that server. This includes Contact
header fields that are stored by a registrar. The header field contains a
decimal integer number of seconds from 0 to (2**32)-1.
Allowing the registrar to set the registration interval protects it against
excessively frequent registration refreshes while limiting the state that it
needs to maintain and decreasing the likelihood of registrations going
stale. The expiration interval of a registration is frequently used in the
creation of services. An example is a follow-me service, where the user may
only be available at a terminal for a brief period. Therefore, registrars
should accept brief registrations; a request should only be rejected if the
interval is so short that the refreshes would degrade registrar performance.
If a User Agent receives a 423 (Interval Too Brief) response to a REGISTER request,
it MAY retry the registration after making the expiration interval of all
contact addresses in the REGISTER request equal to or greater than the
expiration interval within the Min-Expires header field of the 423
(Interval Too Brief) response. The Min-Expires header field that states the
minimum expiration interval the registrar is willing to honor.
For Example:
Min-Expires: 60
author:
BEA Systems, NIST
version:
1.2 |