TCP/IP Configuration and Management Manual

NonStop TCP/IP Processes and Protocols
TCP/IP Configuration and Management Manual—427132-004
B-2
Addressing
system appears as more than one logical host, a one-to-one correspondence between
a logical host on a network and its Internet address on that network still exists. Multiple
NonStop TCP/IP processes in a system on the same IP network must be represented
by multiple Internet addresses, so that they appear to the IP network as multiple hosts.
An Internet address is a four-octet (32-bit) numeric value identifying a particular
network (network address portion) and a local host on that network (local address
portion), as defined in RFC 1010. The standard external representation of an Internet
address—known as dotted decimal format—is the ASCII value of each of the four
octets, separated by periods (for instance, 133.50.85.43). Each octet value is a number
in the range 0 to 255 inclusive, expressed either in decimal with no prefix or in
hexadecimal preceded by the characters 0X (with X in either upper-case or lower-
case). For example, two other ways to express the address just given are all
hexadecimal (0x85.0x32.0x55.0x2b), and a combination of decimal (ASCII) and
hexadecimal (133.0X32.85.0X2B). Example B-1 shows how a 32 bit address translates
into dotted decimal format.
Network Order and Host Order
When describing some support routines in the socket library, this manual (and others in
the NonStop TCP/IP library) refers to Internet addresses or port numbers as being in
network order or in host order. These terms refer to the order in which the octets are
stored in arguments passed to or returned by the routines.
The Internet standard for transmission of 32-bit integers specifies that the
most-significant octet appears first. However, not all hosts store integers in the same
way. Thus, the direct copying of octets from one host to another can change the value
of a number. The standard specifies that sending hosts must translate from their local
integer representation (local order) to network order (most-significant octet first).
Receiving hosts are required to translate from network order to local order.
On NonStop systems, the network order is the same as the host order.
Internet Address Classes
If you want to connect a LAN or a host through a router or gateway to any network in
the Internet, you must apply to have a range of Internet addresses assigned to you by
the Network Information Center (NIC) operated by SRI International. The NIC’s mailing
address is:
DDN Network Information Center
SRI International, EJ291
Example B-1. Dotted Decimal Format for IP Addresses
The 32 bit Internet address:
10000010 00001010 000001110 00011110
is written in the more readable decimal form as:
130.10.6.30