Nortel VoIP Gateway, Configuration Manual

Page: 24 / 220

24 Prerequisites checklist
P0606298 02
QoS routing
To minimize voice jitter over low bandwidth connections, the VoIP Gateway can assign specific
DiffServ Marking in the IPv4 header of the IP telephony data packets.
The DiffServ Code point (DSCP) is contained in the second byte of the IPv4 header. DSCP is used
by the router to determine how the packets will be separated for Per Hop Behavior (PHB). The
DSCP is contained within the DiffServ field, which was known as the ToS field in older versions.
Prerequisites checklist
Before you set up VoIP trunks on the VoIP Gateway, complete the following checklists to ensure
that the system is correctly set up. Some questions do not apply to all installations.
This guide contains a number of appendices that explain various aspects of the system directly
related to IP telephony functions.
This section includes the following checklists:
• “Network diagram” on page 24
• “Network devices” on page 25
• “Network assessment” on page 25
Network diagram
To aid in installation, a Network Diagram is needed to provide a basic understanding of how the
network is configured. Before you install IP functionality, you must have a network diagram that
captures all of the information described in the following table.
Table 1 Network diagram prerequisites
Prerequisites Yes
1.a Has a network diagram been developed?
1.b Does the network diagram contain any routers, switches or bridges with corresponding
IP addresses and bandwidth values for WAN or LAN links?
1.c Does the network diagram contain IP Addresses, netmasks, and network locations of all Norstar VoIP
Gateways?
1.d Does the network diagram contain IP Addresses and netmasks of any other IP Telephony gateways
that you need to connect to?
1.e Does the network diagram contain the IP address for any Gatekeeper that may be used?