Ip Networks, Addressing, And Masks - Nortel Optical Multiservice Edge 6130 Planning Manual

IP networks, addressing, and masks

This section briefly explains the concepts of IP (Internet Protocol, version 4)
addressing and uses examples from DCN to illustrate.
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Every interface within an IP system must have a unique IP address (four
bytes expressed in decimal and separated by dots [for example,
192.168.12.43]). For more information on this notation, refer to
decimal notation for IP addresses on page
The IP addresses available for the system are divided into networks and
further subdivided into subnetworks.
Devices must be grouped together such that they are directly connected
only to other devices with IP addresses conforming to the same
subnetwork addresses.
There are two groups of networks: public and private networks.
— Public networks are those networks which can be connected to the
Internet; therefore they are accessible from any device outside that
network, as long as this device is also connected to the Internet.
— Private networks are isolated from the outside world; therefore they
cannot be connected to the Internet, and as such they are not accessible
by any device that does not belong to the same network. Well-defined
ranges of addresses are reserved for private networks.
– One of the address ranges available for private networks is
192.168.x.y (x = 0 to 255, y = 0 to 255, which is the decimal
representation of an 8-bit binary number); 'x' is the part of the IP
address which is available for the network address. For example,
192.168.1.0, 192.168.2.0, and 192.168.3.0 are three different
network addresses. Every device or interface connected to network
192.168.1.0 must have an IP address that is 192.168.1.y, where 'y'
is the part of the IP address which is available for both the
subnetworks and the host ID (identifier).
The subnetwork mask identifies the number of bits allocated to the host ID
and the number allocated to the subnetwork.
When subnetting a network, two addresses are not available: those
identified by all ones (used as a broadcast address), and all zeros (reserved
by convention as it is used to identify the network).
As for subnets, host addresses of all ones (broadcast) and all zeros (by
convention) are not available.
The network designer will decide how many bits define the subnetwork
and how many define the host ID, according to the actual and possible
future network architecture.
Planning Guide NT6Q92MA Rel 1.0 Iss 1 Standard September 2006
Appendix A: Data communications planning 10-93
10-94.
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