User`s manual

SIP User's Manual 9. Networking Capabilities
Version 5.0 247 December 2006
9 Networking Capabilities
9.1 Ethernet Interface Configuration
Using the parameter ‘EthernetPhyConfiguration‘, users can control the Ethernet connection
mode.
Either the manual modes (10 Base-T Half-Duplex, 10 Base-T Full-Duplex, 100 Base-TX
Half-Duplex, 100 Base-TX Full-Duplex) or Auto-Negotiate mode can be used.
Auto-Negotiation falls back to Half-Duplex mode when the opposite port is not Auto-
Negotiate, but the speed (10 Base-T, 100 Base-TX) in this mode is always configured
correctly. Note that configuring the gateway to Auto-Negotiate mode while the opposite port
is set manually to Full-Duplex (either 10 Base-T or 100 Base-TX) is invalid (as it causes the
gateway to fall back to Half-Duplex mode while the opposite port is Full-Duplex). It is also
invalid to set the gateway to one of the manual modes while the opposite port is either
Auto-Negotiate or not exactly matching (both in speed and in duplex mode). Users are
encouraged to always prefer Full-Duplex connections to Half-Duplex ones and 100 Base-
TX to 10 Base-T (due to the larger bandwidth). It is strongly recommended to use the same
mode in both link partners. Any mismatch configuration can yield unexpected functioning of
the Ethernet connection.
Note that when remote configuration is performed, the gateway should be in the correct
Ethernet setting prior to the time this parameter takes effect. When, for example, the
gateway is configured using BootP/TFTP, the gateway must perform many Ethernet-based
transactions prior to reading the ini file containing this gateway configuration parameter.
To work around this problem, the gateway always uses the last Ethernet setup mode
configured. This way, if users want to configure the gateway to work in a new network
environment in which the current Ethernet setting of the gateway is invalid, they should first
modify this parameter in the current network so that the new setting holds next time
gateway is restarted. After reconfiguration has completed, connect the gateway to the new
network and restart it. As a result, the remote configuration process that takes place in the
new network uses a valid Ethernet configuration.
9.2 NAT (Network Address Translation) Support
NAT is a mechanism that maps a set of internal IP addresses used within a private network
to global IP addresses, providing transparent routing to end hosts. The primary advantages
of NAT are (1) Reduction in the number of global IP addresses required in a private
network (global IP addresses are only used to connect to the Internet); (2) Better network
security by hiding its internal architecture.
Figure 9-1 below illustrates the NAT architecture.
Figure 9-1: NAT Functioning