Udp Port Selection; Rsvp And Rtcp - Avaya 4600 Series Administrator's Manual

4600 Series IP Telephone LAN Administrator's Guide

UDP Port Selection

Some data networks include equipment that can perform UDP port selection. This is a mechanism
by which packets with port numbers in a given range are given priority over packets with port
numbers outside that range.
To support UDP port selection, the 4600 Series IP Telephones can be administered either from the
network, via appropriate administration of the DHCP or TFTP servers, or at the telephone itself, via
dialpad input. Specific implementation details for local administration are in the 4600 Series IP
Telephone Installation Guide, and, for remote administration, in
and Application Files
on the DEFINITY TN2302AP board. This port number can be used to administer routers, etc. that
support UDP port selection, to maximize the priority given to the voice packets being exchanged
between the DEFINITY and the telephone.
The default value for MCPORT is 1719. DEFINITY must be administered to use a port within the
proper range for the specific LAN, and the IP Telephone(s) will copy that port. A related parameter
is PORTAUD, which is the RTP port used by DEFINITY. In accordance with standards RFC 1889
and 1890, the IP Telephone uses a default value for PORTAUD of 5004. MCPORT and PORTAUD
are both administrable (see

RSVP and RTCP

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
A to destination B), jitter, etc. RTCP itself does not improve QoS, but it provides information to you
to help identify where problem areas might be.
You cannot change the telephone's RSVP or RTCP parameters directly on the telephone or via
TFTP or DHCP administration. The only way to change these parameters is by appropriate
administration of the DEFINITY switch. See DEFINITY administration material for more detail.
QoS
4-22
on page 4-18. In summary, the system value MCPORT represents the port
Administering Options for the 4600 Series IP
4
4600 Series IP Telephone Scripts
Telephones).
4