User's Manual

Avaya Branch Gateway Manager 10.0 Page 786
15-601011 Issue 29r (Friday, November 02, 2012)B5800 Branch Gateway
10. Data Routing
The system is a network router. In this role it can connect users on its LAN to remote services by using WAN links and
telephone trunk connections. It can also allow users to dial-in and then act as if they were using a PC on the LAN.
As well as being a network router, the system is a telephone system. These dual roles allow it to support a range of
functions that involve traffic between the network and telephony interfaces. These functions use internal data channels.
The number of internal data channels that can be connected from the system's LAN interface to its telephony interface at
any time is restricted.
· An internal data channel is a connection between the system's telephony and LAN interfaces. For example a
Voicemail connection, an internet connection or a RAS user.
· Calls using a VCM channel do not use a data channel.
· The number of data channels in use does not necessarily match the number of users:
· Several LAN network users, browsing the internet using the same service to an ISP would be a single data
channel.
· Several dial-in network users would each have a separate data channel.
· The maximum number of data channels that can be simultaneously in use for voicemail is restricted. These
channels also require entry of an appropriate license.
The restriction depends on the type of control unit being used.
Internal Data
Channels
Maximum Data Channels
for Voicemail
48
[1]
40
1.Reduced to 44 when an IP500 4-Port Expansion card is installed.
10.1 Network Address Translation (NAT)
NAT allows the addresses used within your LAN to be replaced by a different address when connecting to an external
service.
Typically a service provider will allocate you a single IP address to be used when connecting to their service. NAT allows
all your user's traffic to appears to be coming from that single address without having to change any of your user's real
addresses. This is useful as internally most networks use addresses that have been reserved for public use within
networks but are not valid for routing across the internet (since the same addresses may be being used on other
networks). Also as stated it allows multiple users to use the same service simultaneously.
The use of NAT is automatically enabled if the system Service being used includes an IP address that is not in the same
domain as the its LAN1 IP address.
An exception to the above applies for systems with two LAN's, LAN1 and LAN2. For these units, on each LAN, Enable
NAT can be selected and then applied to traffic between the two LAN's.
10.2 DHCP
The system can act as a simple DHCP server. When switched on with a defaulted configuration, the Control Unit request
IP address information from a DHCP server. If it gets no response it assumes the role of DHCP server for the LAN.
In DHCP Server mode, by default the Control Unit issues itself the address 192.168.42.1. It allocates 200 addresses for
DHCP clients, 192.168.42.1 to 19.168.42.200. This leaves 192.168.42.201 to 192.168.42.254 available for any
computers that need to be allocated a fixed or static IP address. 192.168.42.255 is not used as this is a broadcast
address for the LAN.