  Quantum key distribution (QKD) has been developed within the last decade that
is provably secure against arbitrary computing power, and even against quantum
computer attacks. Now there is a strong need of research to exploit this
technology in the existing communication networks. In this paper we have
presented various experimental results pertaining to QKD like Raw key rate and
Quantum bit error rate (QBER). We found these results over 25 km single mode
optical fiber. The experimental setup implemented the enhanced version of BB84
QKD protocol. Based upon the results obtained, we have presented a network
design which can be implemented for the realization of large scale QKD
networks. Furthermore, several new ideas are presented and discussed to
integrate the QKD technique in the classical communication networks.
