Digital Equipment RapidPrint 500, Reference Manual, Page: 21 / 192

Concepts TCP/IP
2 - 5
2.5 TCP/IP
2.5.1 IP Addresses
Every TCP/IP node on a network has an IP address, which is unique to that network, in addition
to the Ethernet Address, which is unique across all hardware anywhere in the world. The IP
address provides information needed to forward packets across multiple networks, if necessary.
The address is of the form n.n.n.n, where each n is a number from zero to 254, as in 192.0.0.1. The
exception is that there cannot be a zero in the last segment of the address.
NOTE: The number 255 is strictly reserved for broadcast packets.
A unique address has to be specified on the RapidPrint 500 before any of the TCP/IP functionality
is available. See your Configuration Guide for more information on configuring the IP address.
2.5.2 Subnetworks
Usually, a TCP/IP internet is broken down into “networks,” where a host is able to see only the
hosts on its own network or sub-unit. TCP/IP networks then rely on routers (or gateways) to
transfer network traffic to hosts on other networks.
Routers are typically connected to two or more networks, and will pass, or route, TCP/IP mes-
sages across network boundaries. The RapidPrint 500 can be told explicitly which hosts are the
gateways for the local network. If no gateways are currently specified, the RapidPrint 500 will lis-
ten to routing-protocol packets (for example, RIP) to decide which hosts are acting as gateways.
NOTE: See Set/Define Server Gateway for more details.
The RapidPrint 500 decides at connection time whether the desired TCP/IP host is on the local
network segment with the help of the subnet mask on the server. This mask tells how much of the
IP address is the network address, which is applied to the IP addresses of both the RapidPrint 500
and the remote host. If the resulting addresses are identical, the connection is deemed local and
the host is contacted directly. If not, the connection attempt and all subsequent messages to this
host will be directed to the RapidPrint 500’s gateway host for forwarding. The subnet mask, if not
set explicitly, will be automatically configured for the given IP address.
NOTE: See Set/Define Server Subnet Mask for more details.
2.5.3 Simple Network Management Protocol (SNMP)
The RapidPrint 500 supports the SNMP network protocol, which allows hosts on the network to
query nodes for counters and network statistics and change some parameters on those nodes. The
form of these requests is documented by RFC 1098. The list of items that can be queried and/or set
and the type of data used, such as integer and string, are both documented in various Manage-
ment Information Bases (MIBs). MIBs cover a variety of things, such as parallel port status, and
counters and IP address resolution tables.