Cisco Cisco Expressway Maintenance Manual
Any dialog-forming requests, such as INVITE and SUBSCRIBE, that contain Route Sets are rejected. Requests that do
not have Route Sets are proxied as normal in accordance with existing call processing rules.
not have Route Sets are proxied as normal in accordance with existing call processing rules.
Expressway as a SIP Registrar
For a SIP endpoint to be contactable via its alias, it must register its Address of Record (AOR) and its location with a
SIP registrar. The SIP registrar maintains a record of the endpoint’s details against the endpoint’s AOR. The AOR is the
alias through which the endpoint can be contacted; it is a SIP URI and always takes the form
SIP registrar. The SIP registrar maintains a record of the endpoint’s details against the endpoint’s AOR. The AOR is the
alias through which the endpoint can be contacted; it is a SIP URI and always takes the form
username@domain
.
When a call is received for that AOR, the SIP registrar refers to the record to find its corresponding endpoint. (Note
that the same AOR can be used by more than one SIP endpoint at the same time, although to ensure that all
endpoints are found they must all register with the same Expressway or Expressway cluster.)
that the same AOR can be used by more than one SIP endpoint at the same time, although to ensure that all
endpoints are found they must all register with the same Expressway or Expressway cluster.)
A SIP registrar only accepts registrations for domains for which it is authoritative. The Expressway can act as a SIP
registrar for up to 200 domains. To make the Expressway act as a SIP registrar, you must configure it with the
registrar for up to 200 domains. To make the Expressway act as a SIP registrar, you must configure it with the
for which it will be authoritative . It will then handle registration requests for any endpoints attempting to
register against that domain. Note that the Expressway will also accept registration requests where the domain
portion of the AOR is either the FQDN or the IP address of the Expressway. Whether or not the Expressway accepts a
registration request depends on its
portion of the AOR is either the FQDN or the IP address of the Expressway. Whether or not the Expressway accepts a
registration request depends on its
scenario, the Expressway provides secure firewall traversal and line-side support for Unified CM registrations. When
configuring a domain, you can select whether Cisco Unified Communications Manager or Expressway provides
registration and provisioning services for the domain.
configuring a domain, you can select whether Cisco Unified Communications Manager or Expressway provides
registration and provisioning services for the domain.
SIP endpoint registration
There are two ways a SIP endpoint can locate a registrar with which to register: manually or automatically. The option
is configured on the endpoint itself under the SIP Server Discovery option (consult your endpoint user guide for how
to access this setting; it may also be referred to as Proxy Discovery).
is configured on the endpoint itself under the SIP Server Discovery option (consult your endpoint user guide for how
to access this setting; it may also be referred to as Proxy Discovery).
■
If the Server Discovery mode is set to automatic, the endpoint will send a REGISTER message to the SIP
server that is authoritative for the domain with which the endpoint is attempting to register. For example, if an
endpoint is attempting to register with a URI of
server that is authoritative for the domain with which the endpoint is attempting to register. For example, if an
endpoint is attempting to register with a URI of
john.smith@example.com
, the request will be sent to the registrar
authoritative for the domain
example.com
. The endpoint can discover the appropriate server through a variety of
methods including DHCP, DNS or provisioning, depending upon how the video communications network has
been implemented.
been implemented.
■
If the Server Discovery mode is set to manual, the user must specify the IP address or FQDN of the registrar
(Expressway or Expressway cluster) with which they want to register, and the endpoint will attempt to register
with that registrar only.
(Expressway or Expressway cluster) with which they want to register, and the endpoint will attempt to register
with that registrar only.
The Expressway is a SIP server and a SIP registrar.
■
If an endpoint is registered to the Expressway, the Expressway will be able to forward inbound calls to that
endpoint.
endpoint.
■
If the Expressway is not configured with any SIP domains, the Expressway will act as a SIP server. It may proxy
registration requests to another registrar, depending upon the SIP registration proxy mode setting.
registration requests to another registrar, depending upon the SIP registration proxy mode setting.
Registration refresh intervals
Depending on the typical level of active registrations on your system, you may want to configure the Standard
registration refresh strategy to Variable and set the refresh intervals as follows:
registration refresh strategy to Variable and set the refresh intervals as follows:
Active registrations
Minimum refresh interval
Maximum refresh interval
1–100
45
60
101–500
150
200
501–1000
300
400
1000–1500
450
800
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Cisco Expressway Administrator Guide
Protocols