Juniper IGP - CONFIGURATION GUIDE V11.1.X, Configuration Manual

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For example, without CIDR, the class C network address 192.56.0.0 would be an
illegal address. With CIDR, the address becomes valid with the notation:
192.56.0.0/16. The /16 indicates that 16 bits of mask are being used (counting from
the far left). This would be similar to an address 198.32.0.0. with a mask of
255.255.0.0.
A network is called a supernet when the prefix boundary contains fewer bits than
the network’s natural mask. For example, a class C network 192.56.10.0 has a natural
mask of 255.255.255.0. The representation 192.56.0.0/16 has a shorter mask than
the natural mask (16 is less than 24), so it is a supernet.
Figure 5 on page 11 shows how CIDR can reduce the number of entries globally in
Internet routing tables. A service provider has a group of customers with class C
addresses that begin with 192.56. Despite this relationship, the service provider
announces each of the networks individually into the global Internet routing mesh.
Figure 5: Routing With and Without CIDR
Adding and Deleting Addresses
This section provides information about adding or deleting IP addresses.
Multinetting is adding more than one IP address to an IP interface—that is, a primary
address and one or more secondary addresses.
To make an interface unnumbered, see “Setting Up an Unnumbered Interface” on
page 39.
Adding a Primary Address
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The primary address must be the first address added to the interface.
■
Adding a new primary address overwrites the existing primary address.
IP Addressing
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Chapter 1: Configuring IP