Cisco TelePresence Administrator's Manual page 86

Protocols
Field Description
Standard The method used to generate the SIP registration expiry
registration period (the period within which a SIP endpoint must re-
refresh register to prevent its registration expiring) for standard
strategy registrations.
Maximum: uses the lesser of the configured Maximum
refresh value and the value requested in the registration.
Variable: generates a random value between the
configured Minimum refresh value and the lesser of the
configured Maximum refresh value and the value
requested in the registration.
The default is Maximum.
Standard The minimum allowed value for a SIP registration refresh
registration period for standard registrations. Requests for a value
refresh lower than this will result in the registration being rejected
minimum with a 423 Interval Too Brief response. The default is 45
seconds.
Standard The maximum allowed value for a SIP registration refresh
registration period for standard registrations. Requests for a value
refresh greater than this will result in a lower value being returned
maximum (calculated according to the Standard registration
refresh strategy). The default is 60 seconds.
Outbound The method used to generate the SIP registration expiry
registration period for outbound registrations.
refresh
Maximum: uses the lesser of the configured Maximum
strategy
refresh value and the value requested in the registration.
Variable: generates a random value between the
configured Minimum refresh value and the lesser of the
configured Maximum refresh value and the value
requested in the registration.
The default is Variable.
Outbound The minimum allowed value for a SIP registration refresh
registration period for outbound registrations. Requests for a value
refresh lower than this will result in the registration being rejected
minimum with a 423 Interval Too Brief response. The default is 600
seconds.
Cisco VCS Administrator Guide (X8.1.1)
Configuring SIP
Usage tips
The Maximum setting uses the
requested value providing it is
within the specified maximum and
minimum ranges.
The Variable setting calculates a
random refresh period for each
registration (and re-registration)
request in an attempt to continually
spread the load. The VCS never
returns a value higher than what
was requested.
This applies only to endpoints
registered with the VCS. It does not
apply to endpoints whose
registrations are proxied through
the VCS.
See Registration refresh intervals
[p.82]
These options work in the same
manner as for the Standard
registration refresh strategy.
However, outbound registrations
allow a much higher maximum
value than standard registrations.
This is because standard
registrations use the re-registration
mechanism to keep their
connection to the server alive. With
outbound registrations the keep-
alive process is handled by a
separate, less resource-intensive
process, meaning that re-
registrations (which are more
resource-intensive) can be less
frequent.
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