Huawei v200r001 user manual DDR Configuration, Brief Introduction to Dial Configuration

User Manual - Configuration Guide (Volume 3)	Chapter 1
Versatile Routing Platform	DDR Configuration

Chapter 1 DDR Configuration

1.1 Brief Introduction to Dial Configuration

VRP1.3 provides subscribers with a perfect dial solution:

zSupport various dial interfaces, including asynchronous serial ports, ISDN BRI interface and ISDN PRI interface, for subscribers to choose from according to networking needs and network conditions.

zProvide powerful DDR (Dial-on-Demand Routing) function to meet the needs of subscribers for various network topologies.

zSupport link layer protocols like PPP.

zSupport network layer protocols like IP and IPX.

zSupport to run dynamic routing protocols like RIP on dial interfaces.

zSupport flexible dial interface backup modes.

zProvide, at asynchronous dial interfaces, powerful control on various Modems.

zHighly interoperable with the dial functions of other various routers of the industry.

The following are the meanings of terms used in this chapter.

zPhysical interface: interface that physically exists, like Serial0 interface or Bri0 interface.

zDialer interface: logical interface that is set for DDR configuration. Specific physical interfaces can be bound to Dialer interface to enable DDR.

zDial interface: a generic term for any interface used for dial connection—possibly a logical Dialer interface, or a physical interface bound to the Dialer interface, or a physical interface that directly enables DDR.

zDial string: PSTN telephone number or ISDN telephone number

zLegacy DDR (Legacy DDR): a DDR configuration mode as compared with the “Dialer Profile”.

zDialer Profile (Dialer Profiles): developed to meet the needs of various dial configurations for some common physical interfaces.

1.2Introduction to DDR Technology

DDR is short for Dial-on-Demand Routing, referring to the routing technique used for interconnection of routers through PSTN. Currently there are two major kinds of public switched networks, PSTN (public switched telephone network) and ISDN (integrated services digital network). Dialing is necessary to get connected to them.

DDR is adopted when routers are interconnected by asynchronous serial ports through PSTN, or by ISDN BRI/PRI interface through ISDN. In most cases, routers are not connected. Only if there are packets to be transferred between them, will DDR be started and dialup connection established between them to transfer packets. When the links are idle, DDR will automatically disconnect them— in other words, “dial-on- demand”.

Therefore, DDR is quite cost-effective when there is not much information between two points and, if any, it is transferred in burst mode.

DDR is not a protocol, hence no international standards. It is implemented by various router vendors themselves as needed.

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