The design of cable television IP access network based on hot standby router protocol

The tri-networks integration, originally defined as inter-infiltration and integration among the telecommunications networks, cable TV networks and the Internet networks by independent design and operation, primarily means the integration of high layer service applications. The interconnection is achieved at the network layer, the inter-infiltration and intersection at the business layer and the unified IP communication protocol used at the application layer. The Cable Television (CATV) two-way IP Access Network is integrated with the other two networks through telecommunications networks and Internet networks, which should offer more services, such as Interactive TV service, Broadband data service and other digital data services. The characteristics of foregoing services require high stability, high reliability and high fault-tolerance for the IP access network. For high availability, multilayer switches should offer a means of preventing one switch (gateway) failure from isolating an entire VLAN. The Hot Standby Router Protocol (HSRP) is a Cisco-proprietary protocol developed to allow several routers (or multilayer switches) to appear as a single gateway IP address, which provides network redundancy for IP networks, ensuring that user traffic immediately and transparently recovers from first hop failures in network edge devices or access circuits. Basically, each of the routers that provides redundancy for a given gateway address is assigned to a common HSRP group. One router is elected as the primary, or active, HSRP router; another is elected as the standby HSRP router; and all the others remain in the listen HSRP state. The routers exchange HSRP hello messages at regular intervals so that they can remain aware of each other´s existence and that of the active router. This article introduces relevant technology of the hot standby router protocol, and also provides detail design for a cable television IP access network with fault-tolerant capacity and load balan- ing capacity based on the hot standby router protocol. The article gives some program to realize design with HSRP.