AudioCodes Mediapack mp-11x, Руководство пользователя

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SIP User's Manual 372 Document #: LTRT-65409
MediaPack Series
When the client receives a response to its request from the identified NTP server it must be
interpreted based on time zone, or location, offset that the system is to a standard point of
reference called the Universal Time Coordinate (UTC). The time offset that the NTP client
uses is configurable using the Embedded Web Server (refer to 'Configuring the Application
Settings' on page
168 ), the
ini
file (NTPServerUTCOffset), or via an SNMP MIB object
(refer to the
SIP Series Reference Manual
).
If required, the clock update is performed by the client as the final step of the update
process. The update is performed in such a way as to be transparent to the end users. For
instance, the response of the server may indicate that the clock is running too fast on the
client. The client slowly robs bits from the clock counter to update the clock to the correct
time. If the clock is running too slow, then in an effort to catch the clock up, bits are added
to the counter, causing the clock to update quicker and catch up to the correct time. The
advantage of this method is that it does not introduce any disparity in the system time that
is noticeable to an end user or that could corrupt call timeouts and timestamps.
8.8 IP QoS via Differentiated Services (DiffServ)
DiffServ is an hitecture providing different types or levels of service for IP traffic. DiffServ
(according to RFC 2474) offers the capability to prioritize certain traffic types depending on
their priority, thereby, accomplishing a higher-level QoS at the expense of other traffic
types. By prioritizing packets, DiffServ routers can minimize transmission delays for time-
sensitive packets such as VoIP packets.
The gateway can be configured to set a different DiffServ value to IP packets according to
their class-of-service (i.e., Network, Premium Media, Premium Control, Gold, and Bronze).
For the mapping of an application to its class-of-service, refer to 'IEEE 802.1p/Q (VLANs
and Priority)' on page
373 .
The DiffServ parameters are described in 'Networking Parameters' on page 256 .
8.9 VLANS and Multiple IPs
8.9.1 Multiple IPs
Media, Control, and Management (OAM) traffic in the gateway can be assigned one of the
following IP addressing schemes:
„ Single IP address for all traffic (i.e., Media, Control, and OAM).
„
Separate IP address for each traffic type:
For separate IP addresses, the different traffic types are separated into three
dedicated networks. Instead of a single IP address, thegateway is assigned three IP
addresses and subnet masks, each relating to a different traffic type. This architecture
enables you to integrate the gateway into a three-network environment that is focused
on security and segregation. Each entity in the gateway (e.g., Web and RTP) is
mapped to a single traffic type (according to the table in 'IEEE 802.1p/Q (VLANs and
Priority)' on page
373 ) in which it operates.
„ Dual IP mode (two separate IP addresses -- one for a specific traffic type and the
other for a combination of two traffic types):