Rsvp And Rtcp; Vlan Considerations - Avaya
4600 Series Administrator's Manual

RSVP and RTCP

Avaya IP Telephones implement the Resource ReSerVation Protocol (RSVP) to support WAN
bandwidth management. RSVP is administered from the call server. Avaya IP Telephones
implement the RTP Control Protocol (RTCP) so that Avaya's Voice over IP (VoIP) Monitoring
Manager (VMON) software can provide real-time monitoring and historical data of the audio quality
of VoIP calls.
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 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 switch. See your DEFINITY
more detail.

VLAN Considerations

If your LAN environment does not include Virtual LANs (VLANs), ignore this section. Otherwise,
this section contains information on how to administer 4600 Series IP Telephones to minimize
registration time and maximize performance in a VLAN environment.
The system value L2QVLAN (initially set to "0"), identifies the 802.1Q VLAN IDentifier. This default
value indicates "priority tagging" as defined in IEEE 802.IQ Section 9.3.2.3, which specifies that
the Ethernet switch in your network closet should automatically insert the default VLAN for the
switch port without changing the user priority of the frame (cf. IEEE 802.1D and 802.1Q).
However, you might not want the default VLAN to be used for voice traffic; for example, you may
have administered a VLAN specifically for IP telephony. In this case, you need to ensure the
switch is configured to allow frames tagged by the 4600 Series IP Telephone through without
overwriting or removing them. In addition, you will want to set the system value L2QVLAN to the
VLAN ID appropriate for your voice LAN.
4
® TM
/MultiVantage administration material for
4
Server Administration
VLAN Considerations
4-27