Circuitless Ip Interface - Nortel Optical Multiservice Edge 6130 Planning Manual

Address of packet is:
00101111.00001001.01000000.10101100
Mask is:
11111111.11111111.11110000.00000000
This means that the network part of the address is:
00101111.00001001.01000000.00000000
The device part of the address is:
00000000.00000000.00000000.10101100
occupying the last 12 bits.
CIDR (Classless Inter-Domain Routing) addresses represent masks in a
different way. A CIDR address is defined by a starting address and a mask
which defines the size of the address allocation. For example:
An allocation of addresses in the range 196.0.16.0 to 196.0.31.255 can be
represented by:
196.0.16.0/20 (see note)
where the 20 is a mask of 20 contiguous 1 bits.
Start address is:
11000100.00000000.00010000.00000000
End address is:
11000100.00000000.00011111.11111111
And the mask is:
11111111.11111111.11110000.00000000
The last 12 bits are available to the user to use as subnet address and device
address.
Note: This notation is conventional for CIDR addresses. However, the
method in which an IP address is configured can vary according to the
router where it is performed. For example, the IP address notation
196.0.16.0/20 can be used to configure a Cisco router, whereas Nortel
Networks routers require the full notation 196.0.16.0 with the subnetwork
mask 255.255.240.0. There is no substantial difference between these two
methods.

Circuitless IP interface

A circuitless IP interface is a virtual interface that exists in software only. The
special property of this interface is that it always exists and is therefore always
included in the routing tables. Ethernet and serial interfaces cease to exist if a
connector falls out, or if the device at the other end of the cable fails for any
reason. The interface then shuts down and is removed from the routing tables.
Planning Guide NT6Q92MA Rel 1.0 Iss 1 Standard September 2006
Appendix A: Data communications planning 10-95