As we already know, the extended network prefix is used and
therefore VLSM requires it to be carried out. To accomplish the
VLSM requirement, two protocols are used OSPF and I-IS-I as the
Interior Gateway Protocol, even though you could use RIP-2 a
fixed in RFC 1388. These protocols carry the extended network
prefix in each advertisement. If the protocol does not carry the
prefix information, the router makes a lookup in its global
configured routing table. If the information is not found there
it applies a local mask and delivers the information as long as
the host exists. Make note that the higher the extended network
prefix is, it has less hosts and gets faster to its destination.
This is known as a forwarding algorithm. For example if a /16
class B network has been defined as /22 bit extended network-
prefix which has 64 subnets (26), that leaves 10 bits for the
hosts which is equal to (210-2) 1022 hosts per subnet. Now the
same /16 Class B network has been defined as /26 extended
network-prefix gives us 1