Table 4-2 Decimal Subnet Masks And Prefix Lengths - Lucent Technologies Stinger Compact Remote Getting Started Manual

011
111 — Reserved for the broadcast address of the subnet
Note Early implementations of TCP/IP did not allow zero subnets (subnets with the
same base address as a class A, B, or C network). For example, the subnet
192.32.8.0/30 was illegal because it had the same base address as the class C network
192.32.8.0/24, while the subnet 192.32.8.4/30 was legal. Modern implementations
of TCP/IP support zero subnets, and the Stinger implementation of Routing
Information Protocol (RIP) treats these subnets the same as any other network. Make
sure that you treat zero subnets consistently throughout your network. Otherwise,
you might encounter routing problems.
Table 4-2 shows subnet masks and prefix lengths for a class C network.
Table 4-2. Decimal subnet masks and prefix lengths
Subnet mask
255.255.255.0
255.255.255.128
255.255.255.192
255.255.255.224
255.255.255.240
255.255.255.248
255.255.255.252
255.255.255.254
255.255.255.255
The broadcast address of any subnet has the host portion of the IP address set to all 1s
(ones). The network address (or base address) represents the network itself, because
the host portion of the IP address is all 0s (zeros). For example, suppose that the
Stinger configuration assigns the following address to a remote router:
198.5.248.120/29
The Ethernet network attached to that router has the following address range:
198.5.248.120 — 198.5.248.127
A host route is a special-case IP address with a prefix length of /32. For example:
198.5.248.40/32
Host routes are routes to a single host, rather than to a network or subnet. This is
determined by the fact that a 32-bit netmask does not allow for any host addresses on
The Stinger® Compact Remote ATM DSLAM Getting Started Guide
Number of host addresses
254 hosts + 1 broadcast address, 1 network base
address
126 hosts + 1 broadcast address, 1 network base
address
62 hosts + 1 broadcast address, 1 network base address /26
30 hosts + 1 broadcast address, 1 network base address /27
14 hosts + 1 broadcast address, 1 network base address /28
6 hosts + 1 broadcast address, 1 network base address
2 hosts + 1 broadcast address, 1 network base address
Invalid mask (no hosts)
1 host—a host route
Initial Stand-alone Configuration
Providing a basic system IP configuration
Prefix
length
/24
/25
/29
/30
/31
/32
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