Symbol PDT 8100 Series Product Reference Manual page 124

PDT 8100 Series with Intel XScale Technology Product Reference Guide
The four cradle slots are assigned four private addresses as specified in the Public network
menu shown on page 4-24. Port numbers are then used to determine which cradle slot a
packet goes to.
Using NAPT, the cradle modifies one IP address and port number pair inside each TCP/IP
and UDP/IP packet header. For packets going from cradle to the outside network, NAPT
translates the source address to the cradle's IP address and changes the source port to a
unique port number associated with the cradle slot it came from. For packets coming from
the outside network into the cradle, NAPT maps their destination IP addresses and port
numbers to equivalent private network IP addresses and port numbers.
Limitations of NAPT:
• When using NAPT, some network services do not function.
• NAPT modifies addresses in TCP/IP and UDP/IP headers, so it cannot work with
network services that embed terminal IP addresses inside packet data.
• The cradle assumes that a client sending data with one TCP or UDP source port
expects to receive replies on the same port, but some network services may
respond over a range of ports. You cannot use these network services with NAPT.
• Some services listen to incoming requests from the network. Since port numbers
are usually fixed for a given service, no terminals can be set up as listeners.
Static Address Mode
If there is no DHCP server on your network, you must configure the cradle manually with
the following addresses:
• one IP address for the cradle
• four IP addresses for the four cradle slots
• one IP address for the expansion port
• router/gateway address
• one or more DNS server addresses
• one or more WINS server addresses
• the subnet mask.
See Configuring an Address Mode
4-22
for more information.