4600 Series IP Telephone LAN Administrator’s Guide
SNMP
2-4
NAT 2
A Network Address Translator is an application that can be administered between your n etwork
and the Internet. The NAT translates network layer IP addresses so your local intranet IP
addresses can duplicate global, Internet addresses. A detailed discussion of NAT is beyond the
scope of this document, but it should be noted that use of NAT can lead to problems affecting the
consistency of addressing throughout your network. In Release 1.6 and earlier releases of the
4600 Series IP Telephones, NAT is not recommended for networks handling IP-based telephony
traffic. As of Release 1.7, all 4600 Series IP Telephones support NAT interworking; hence, there
are no problems with NAT and Release 1.7 of the 4600 Series IP Telephones. Note, however, that
support for NAT does not imply support for Network Address Port Translation (NAPT). Specifically,
the 4600 Series IP Telephones do not support communication to the PBX through any NAPT
device.
NAT requires specific administration on the call server. The capability to have a direct Avaya IP
Telephone-to-Avaya IP Telephone call with NAT (also called “NAT shuffling”) requires Avaya™
Communication Manager Release 1.3 software. See the Administration for Network Con nectivity
document (listed in Related Documents, on page 1-5).
QoS 2
Quality of Service (QoS) is a term covering several initiatives to m aximize the quality of the voice
heard at both ends of a call that originates and/or terminates, on an IP-bas ed telephone. These
initiatives include various prioritization schemes to offer voice pack ets a larger or prioritized share
of network resources. These schemes include standards such as IEEE’s 802.1D and 802. 1Q, the
Internet Engineering Task Force’s (IETF’s) “Differentiated Services,” RTP Control Protocol
(RTCP), Resource ReSerVation Protocol (RSVP), and port-based priority schemes such as UDP
port selection. Documentation for your LAN equipment will elaborate on the extent your n etwork
can support any or all of these initiatives. See Server Admini stration, on page 4-1, for some
implications of QoS for the 4600 Series IP Telephones.
As of Release 1.7, both the 4620 and 4630 families of IP Telephones provided network audio
quality information to the end user that may be of use to the LAN Administrator. As of Release 1.8,
all 4600 Series IP Telephones provide some level of detail about network audio quality. For
specific information, see Network Audio Quality Display on 4600 Series IP Telephones, on page
4-25.
SNMP 2
Simple Network Management Protocol (SNMP) is a family of standards-based protocol s and
procedures to allow vendor-independent data network management. Using a simple set of
protocol commands, an SNMP-compliant device stores information in standard format in one or
more Management Information Bases (MIBs). In general, devices supp ort the standards-specific
MIB termed MIB-II. In addition, devices may define one or more "custom MIBs" th at contain
information about the specifics of the device.