Matrix SETU VFX44L, Системное руководство

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Matrix
167 SETU VFX88L
/
VFX44L V1
System Manual
Network Servers:
There are three types of
network servers
in a SIP network: proxy
server, redirect server and registrar server.
Proxy Server:
A SIP proxy receives a request, makes a determination
about the next server to send it to, and forwards the request, possibly
after modifying some of the header fields. As such, SIP requests can
traverse many servers on their way from UAC to UAS. Responses to
a request always travel along the same set of servers the request
followed, but in reverse order.
Redirect Server:
The redirect server does not forward requests to the
next server. Instead it sends a redirect response back to the client
containing the address of the next server to contact.
SIP Registrar:
SIP Registrar is an entity where SIP users can get
themselves registered. Registrar imparts mobility to the SIP users. A
SIP user can register himself with a registrar. If the user changes his
location, he has to register again with the registrar stating his latest
contact information. Whenever a call is to be delivered to that user,
Registrar can provide the information about the location where the
user was active recently.
RTP:
After a VoIP call is established using SIP, the RTP (Real Time
Protocol) is used to handle voice data transfer in the packets form.
Refer RFC 1889 for more details.
NAT
NAT (Network Address Translation-RFC 1631), is the translation of IP
address of a host in a packet. For example, the source address of an
outgoing packet, used within one network is changed to a different IP
address known within another network.
• One network is designated the inside network and the other is the
outside. Typically, a company maps its local inside network
addresses to one or more global outside IP addresses and unmaps
the global IP addresses on incoming packets back into local IP
addresses. This helps ensure security since each outgoing or