Avaya 4600 Series - Manual (Page 53)

Server Administration
QoS
4-23
In addition, based on the current values for the above parameters, the Network Audio Quality
Screen presents the user with a qualitative assessment of the overall audio quality currently being
experienced. This assessment is based on separate evaluations of the Packet Loss and the total
Network Delay (the sum of Packetization Delay, One-way Network Delay, and Network Jitter
Compensation Delay), and consideration of the codec in use.
The implication of this information for LAN administration depends, of course, on the values
reported by the user and the specific nature of your LAN (topology, loading, QoS administration,
etc.) The major use for this information is to give the user an idea of how network conditions are
affecting the audio quality of the current call. It is assumed you have more detailed tools available
for troubleshooting the LAN.
RSVP and RTCP 4
Resource ReSerVation Protocol (RSVP) is an IETF-standard protocol used by hosts to request
resource reservations throughout a network. RSVP-compliant hosts send messages through a
network to receivers, which respond with messages requesting a type of service and an amount of
resources (e.g., bandwidth) to carry out that service. The host is responsible for admitting
(approving) or rejecting (denying) the request. In a QoS context, RSVP is used to try to reserve
bandwidth in the network for voice calls, on a call-by-call basis. If insufficient bandwidth is available
for the target voice quality, a request to use network bandwidth for a voice call will be rejected.
RTP Control Protocol (RTCP), as its name implies, is a protocol that provides control functions for
Real-time Transport Protocol (RTP). RTP provides end-to-end network services for real-time data
(such as Voice over IP), but does not provide a reservation function, nor does it guarantee any
level of QoS. RTCP supplements RTP by monitoring the quality of the RTP services and can
provide real-time information to users of an RTP service. In a QoS context, RTCP is valuable for
identifying information such as packet loss, 1-way delay (how long a packet has to go from source
Packet Loss "No data" or a decimal percentage. Late and out-of-
sequence packets are counted as lost, if they are
discarded. Packets are not counted as lost until a
subsequent packet is received and the loss confirmed by
the RTP sequence number.
Packetization Delay "No data" or an integer number of milliseconds. The
number reflects the amount of delay in received audio
packets, and includes any look-ahead delay associated
with the codec.
One-way Network Delay "No data" or an integer number of milliseconds. The
number is one-half the value RTCP computes for the
round-trip delay.
Network Jitter
Compensation Delay An integer number of milliseconds reporting the average
delay introduced by the telephone’s jitter buffer.
Parameter Possible Values