FireBrick FB6602, Руководство пользователя

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CIDR and CIDR Notation
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routing table entry - 10.1.2.0/24 and 10.1.3.0/24 - routing table entries for these subnets would appear in a
downstream router.
Note that in either a network/subnet or routing destination specification, the address will be the starting address
of the IP address range being expressed, such that there will be M least significant bits of the address set to
zero, where M = 32 - prefix_length
Combined interface IP address and subnet definitions
Another common use of the CIDR notation is to combine the definition of a network with the specification of
the IP address of an end system on that network - this form is used in subnet definitions on the FB6000, and
in many popular operating systems.
For example, the default IPv4 subnet on the
LAN
interface after factory reset is
10.0.0.1/24
- the address
of the FB6000 on this subnet is therefore
10.0.0.1
, and the prefix length is 24 bits, leaving 8 bits for host
addresses on the subnet. The subnet address range is therefore
10.0.0.0
to
10.0.0.255
A prefix-length of 32 is possible, and specifies a block size of just one address, equivalent to a plain IP address
specification with no prefix notation. This is not the same as a combined subnet and interface-IP-address
definition, as it only specifies a single IP address.
General IP address range specifications
CIDR notation can also be used in the FB6000 to express general IP address ranges, such as in session-rules,
trusted IP lists, access control lists etc. In these cases, the notation is the same as for routing destinations or
subnets, i.e. the address specified is the starting address of the range, and the prefix-length determines the size
of the range.