User guide

Overview IP
4-1
iMG/RG Software Reference Manual (IPNetwork Functions)
4. IPNetwork Functions
4.1 IP
4.1.1 Overview
This chapter describes the main features of the Internet Protocol (IPv4) and how to configure and operate the
AT-iM G models IP interface .
Before you start configuring the IP Stack for your own network requirements, it is essential that you are familiar
with the basic functionality of the IP Stack
The IP Stack allows you to configure basic connectivity for your network to provide IP routing between inter-
faces and to support local applications, such as Telnet, web server, DHCP and so on.
The dual IP Stack implements the following IPv4 protocols:
• Internet Protocol (IP), including RFC 791.
• Includes support for Fragmentation and Reassembly (RFC 0791 and RFC 1812 (section 4.2.2.7))
• Includes support for Subnetting and Classless Interdomain Routing. • Internet Control Message Protocol
(ICMP) (RFC 0792); see ICMP (RFC 972).
• User Datagram Protocol (UDP) - RFC 768
• Transmission Control Protocol (TCP) - RFC 793
• featuring also TCP MSS Clamp;
• Address Resolution Protocol (ARP) for Ethernet - RFC 826 and RFC 894.
• Internet Group Management Protocol (IGMP), Version 2 - RFC 236. Multicast forwarding and IGMP
Proxy (RFC 2236);
• Routing Information Protocol (RIP), Version 2 - RFC 1723; see RIP v2 (for IPv4).
4.1.2 IP Interfaces
In order to use the IP stack, one or more interfaces must be added to the IP stack and attached to a transport.
For IPv4 interfaces, each interface must be configured with an IP address and a subnet mask. Together, these
define the range of addresses which can be reached via the interface withoutpassing through any other routers
Each interface (real and virtual) must have a unique subnet; the range of addresses on each interface must not
overlap with any other interface. The only exception to this is unnumbered interfaces, which may be configured
on point to point links when there is no local subnet associated with the interface.