NonStop Networking Overview

2 Networking Concepts
This section provides a brief overview of networking concepts including the following topics:
• Address Resolution
• Name Resolution
• Allocation of IP Addresses (page 25)
• Routers (page 26)
• Switches (page 26)
• Gateways (page 26)
• Network Interface Name (page 26)
• Firewalls (page 27)
• “IP Security (IPSec)” (page 27)
• IPv6 (page 28)
For more detailed information about Internet concepts and services, see the TCP/IP Configuration
and Management Manual.
Address Resolution
Address resolution refers to the mapping of IP addresses to lower-level addresses and is
accomplished by the static binding of addresses or the dynamic binding of addresses. Static
binding of addresses is used for the NonStop TCP/IP product over X.25. Dynamic binding of
addresses is implemented with the Address Resolution Protocol (ARP) for IPv4 (defined in IEEE RFC
826) and is used for NonStop TCP/IP, NonStop TCP/IPv6 and CIP over Ethernet.
Address resolution with the dynamic binding of addresses for networks involves the use of the
Neighbor Discovery Protocol. Using the Neighbor Discovery Protocol and stateless address auto
configuration, an Integrity NonStop system configured as an IPv6 host discovers other nodes on
the link, determines their link-layer addresses, finds routers, and maintains reachability information
about the paths to active neighbors. See the TCP/IPv6 Configuration and Management Manual
or Cluster I/O Protocols (CIP) Configuration and Management Manual for more information about
the Neighbor Discovery Protocol and stateless address auto configuration in the IPv6 network. See
also, IPv6 (page 28).
Name Resolution
For convenience, hosts are often referred to by name; in addition, for the world wide web, universal
resource locators (URLs) locate a website location. The process of finding the IP address associated
with either a host or a URL is a process of name-to-address mapping, is also called name resolution.
There are two methods of resolving names, by:
• HOSTS File
• Domain Name System (DNS)
HOSTS File
A HOSTS file is an ASCII file on your system, by default in ZTCPIP (Guardian) or /etc (OSS) that
lists the various host names associated with the IP addresses on the system. To use a HOSTS file
for address resolution, you must configure the TCP/IP subsystem to use that HOSTS file; the default
is for the TCP/IP subsystems is to use the Domain Name System (DNS) .
24 Networking Concepts