Supernetting (Advanced TCP/IP)
Because Class B Internet addresses are in short supply, larger networks are now usually granted a contiguous block of several Class C addresses. Unfortunately, this creates very large routing tables since multiple Class C routes have to be defined for each network containing more than 254 nodes. Larger routing tables mean more work for the routers and, therefore, poorer perfor- mance.
Traditional IP - Each class C network must have
a routing table entry
Supernetting (Classless InterDomain Routing) is a technique that allows each of these larger networks to be represented by a single routing table entry.
To do this, supernet addressing does something very different from traditional TCP/IP routing (which allows only one netmask per network). In supernet routing, each supernet can be assigned its own netmask.
Supernetting is defined in RFC 1519.
