CTI 2500-C100, Инструкция по установке и эксплуатации

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CTI 2500 Installation and Operation Guide V2.8 99
APPENDIX C. – IP ADDRESS INFORMATION
IP Address Nomenclature
IP Address
Every host interface on an IP network is identified by a unique IP address. This address is
used to uniquely identify the host and the IP network to which the host belongs.
Each IP address consists of 32 bits, divided into four 8 bit bytes (called
octets ). An IP
address is usually expressed in dotted decimal notation, with each octet expressed as its
decimal equivalent. See the example below.
Notation Byte 1 Byte 2 Byte 3 Byte 4
Binary 11000000 11011111 10110001 00000001
Decimal 192 223 177 1
Although an IP address is a single value, it contains two pieces of information: the Network
ID and the Host ID . The Network ID identifies the IP network to which the host belongs while
the Host ID identifies a specific IP host on that IP network. All IP hosts on a particular IP
network must have the same network ID. Each IP host on a particular IP network must use
must have unique Host ID. The IP protocol sends messages with a destination IP address
that is not on the host’s IP network to the designated router/gateway.
Address Classes
The Internet community originally defined network classes to accommodate networks of
varying sizes. The network class can be determined based on the first octet of its IP
address.
The following table summarizes the relationship between the first octet of a given address
and its Network ID and Host ID fields. It also identifies the total number of Network IDs and
Host IDs for each address class that participates in the Internet addressing scheme. This
example uses w.x.y.z to designate the octets of the IP address.
Class w values*
Network ID Host ID Number of
networks Number of
hosts per net
A 1-126 w x.y.z 126 16,777,214
B 128-191 w.x y.z 16,384 65,534
C 192-223 w.x.y z 2,097,151 254
* Inclusive range for the first octet in the IP address. The address 127 is reserved for
loopback testing and inter-process communication on the local computer; it is not a valid
network address. W values 224 – 239 are used for Class D (IP multicast).