Configuring the Control Module and System Timing
Providing a basic system IP configuration
Stinger® MS+ Getting Started Guide
5-11
000 — Reserved for the network (base address)
001
010
100
110
101
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 5-2 shows subnet masks and prefix lengths for a class C network.
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:
Table 5-2. Decimal subnet masks and prefix lengths
Subnet mask
Number of host addresses
Prefix
length
255.255.255.0
254 hosts + 1 broadcast address, 1 network base
address
/24
255.255.255.128
126 hosts + 1 broadcast address, 1 network base
address
/25
255.255.255.192
62 hosts + 1 broadcast address, 1 network base address /26
255.255.255.224
30 hosts + 1 broadcast address, 1 network base address /27
255.255.255.240
14 hosts + 1 broadcast address, 1 network base address /28
255.255.255.248
6 hosts + 1 broadcast address, 1 network base address
/29
255.255.255.252
2 hosts + 1 broadcast address, 1 network base address
/30
255.255.255.254
Invalid mask (no hosts)
/31
255.255.255.255
1 host—a host route
/32