Instruction manual

Internet Protocol (IP)
Issue 4 May 2003 143555-233-767
802.1p/Q
IEEE standard 802.1Q and 802.1p provide the means to specify both a Virtual
LAN (VLAN) and a frame priority at layer 2 for use by LAN hubs, or bridges, that
can do routing based on MAC addresses. 802.1p/Q provides for 8 levels of
priority (3 bits) and a large number (12 bits) of VLAN identifiers. The VLAN
identifier at layer 2 permits segregation of traffic to reduce traffic on individual
links. Because 802.1p operates at the MAC layer, its presence may vary from
LAN segment to LAN segment within a single network region. Flexibility
requires that 802.1p/Q options be administered individually for each network
interface.
Codecs
Codecs provide the means by which audio is compressed and are typically used in
VoIP. Codecs supported by Communication Manager include G.711, G.723, and
G.729.
Differentiated services (DiffServ)
With the DiffServ option, the system administrator can administer (by region) and
download, to the TN2302AP, the DiffServ Type-Of-Service (TOS) value. This
allows data networking equipment to prioritize the audio stream at the IP level to
promote voice quality. DiffServ makes use of the TOS octet in the existing IP
version 4 header. As such, it may be set by information senders and used by IP
(layer 3) routers within the network.
Dynamic jitter buffers
Propagation delay and jitter is caused when a human’s voice is sampled, encoded,
and packetized for transport over the IP network, but is received and decoded at
different rates. Jitter buffers are used to buffer the audio output to smooth the
conversions. Communication Manager provides dynamic jitter buffers to balance
both delay of conversation and rapid bursts that may occur.
Integration with Cajun rules
Cajun rules provide a central repository for QoS parameters and allows
comprehensive QoS management across routers, switches, and endpoints. QoS
parameters and policies are assigned according to network regions on a network
region and are distributed through enterprise directory gateway to Communication
Manager and to routers and switching devices.