Configuring Napt; Configuring Static Ip Routing; Configuring Rip - Patton electronics IPLink Series Software Configuration Manual

Iplink software release 3.20

Table of Contents

IPLink Software Configuration Guide

higher-layer protocol and service information, such as layer 3 addressing. Hence interfaces are conﬁgured as

part of the IP context and represent logical entities that are only usable if a physical port is bound to them.

An interface name can be any arbitrary string, but for ease of identiﬁcation you should use self-explanatory

names that describe the use of the interface. For example, use names like lan for an IP interface that connects to

the LAN and wan for an interface that connects to the access network or WAN. Avoid names that represent the

nature of the underlying physical port for logical interfaces, like eth0 or serial0, to represent Ethernet port 0 or

serial port 0, since IP interfaces are not strictly bound to a certain physical port. An IP interface can be moved

to another physical port (from an Ethernet to a serial port, for example) while an IPLink is operating. For that

reason, it would be confusing if an interface had name like eth0, but was actually assigned to a serial port. So it

is important to avoid naming a logical interface after a physical port. Instead, assign names to interfaces that

describe their usage and not the physical connection.

Several IP-related conﬁguration parameters are necessary to deﬁne the behavior of such an interface. The most

obvious parameters are the IP address and an IP net mask that belongs to it.

For information and examples on how to create and conﬁgure an IP interface, refer to chapter 11,

conﬁguration"

on page 117.

Conﬁguring NAPT

Network address port translation (NAPT), which is an extension to NAT, uses TCP/UDP ports in addition to

network addresses (IP addresses) to map multiple private network addresses to a single outside address. NAPT

enables small ofﬁces to save money by requiring only one ofﬁcial outside IP address to connect several hosts via

an IPLink to the access network. Moreover, NAPT provides additional security, because the IP addresses of

hosts attached via the IPLink are invisible to the external world. You can conﬁgure NAPT by creating a proﬁle

that is afterwards used on an explicit IP interface. In IPLink software terminology, an IP interface uses a NAPT

proﬁle, as shown in

ﬁgure 17

For information and examples on how to conﬁgure NAPT refer to chapter 12,

on page 128.

Conﬁguring static IP routing

IPLink software allows to deﬁne static routing entries, which are table mappings established by the network

administrator prior to the beginning of routing. These mappings do not change unless the network administra-

tor alters them. Algorithms that use static routes are simple to design and work well in environments in which

network trafﬁc is relatively predictable and where network design is relatively simple.

For information and examples on how to conﬁgure static IP routing, refer to chapter 17,

conﬁguration"

on page 195.

Conﬁguring RIP

The Routing Information Protocol (RIP) is a distance-vector protocol that uses hop count as its metric. RIP is

widely used for routing trafﬁc in the global Internet and is an interior gateway protocol (IGP), which means

that it performs routing within a single autonomous system.

RIP sends routing-update messages at regular intervals and also when the network topology changes. When a

router receives a routing update that includes changes to an entry, it updates its routing table to reﬂect the new

route. The metric value for the path is increased by one, and the sender is indicated as the next hop. RIP rout-