SNMP
Issue 2.2 April 2005 25

QoS

Quality of Service (QoS) is a term covering several initiatives to maximize the voice quality
heard at both ends of a call that originates or terminates on an IP-based telephone. These
initiatives include various prioritization schemes to offer voice packets 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) “Di fferentiated Services,”
●RTP Control Protocol (RTCP),
●Resource ReSerVation Protocol (RSVP), and
●port-based priority schemes such as UDP port selection.
Documentation for your LAN equipment details the extent to which your network can support
any or all of these initiatives. See Server Administrationon page 43, 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. This network audio quality information might be us eful to the
LAN Administrator. As of Release 1.8, all 4600 Series IP Telephones provi de some level of
detail about network audio quality. For specific information, see Network Audio Quality Display
on 4600 Series IP Telephoneson page 77.
SNMP
Simple Network Management Protocol (SNMP) is a family of standards-based protocols 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). Usually, devices support the standards-specific
MIB termed MIB-II. In addition, devices can define one or more “custom MIBs” that contain
information about the device’s specifics.
As of Release 1.1, the 4600 Series IP Telephones are fully compatible with SNMPv2c, a later
version of SNMP, and with Structure of Management Inf ormation Version 2 (SMIv2). The
telephones respond correctly to queries from entities that comply with earlier versions of SNMP,
such as SNMPv1. “Fully compatible” means that the telephones respond to queries directed
either at the MIB-II or the Custom MIB. The 4600 Series IP Telephone Custom MIB is r ead-only.
Read-only means that the values therein cannot be changed externally by means of network
management tools.