Huawei v200r001 Chapter 1 DDR Configuration

User Manual - Configuration Guide (Volume 3)

Versatile Routing Platform Chapter 1

DDR Configuration

1-1

Chapter 1 DDR Configuration

VRP1.3 provides subscribers with a perfect dial solution:

z Support various dial interfaces, including asynchronous serial ports, ISDN BRI

interface and ISDN PRI interface, for subscribers to choose from ac cording to

networking needs and network conditions.

z Provide powerful DDR (Dial-on-Demand Routing) function to meet the needs of

subscribers for various network topologies.

z Support link layer protocols like PPP.

z Support network layer protocols like IP and IPX.

z Support to run dynamic routing pr otocols like RIP on dial interfaces.

z Support flexible dial interf ace backup modes.

z Provide, at asynchronous dial interfaces, powerful control on various Modems.

z Highly interoperable with the dial functions of other various routers of the industry.

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

z Physical interface: interface that physically exists, like Serial 0 interface or Bri0

interface.

z Dialer interface: logical interface that is set for DDR configuration. Specific

physical interfaces can be bound to Dialer interface to enable DDR.

z Dial interf ace: a generic term for any interface used for dial connection—poss ibly a

logical Dialer interface, or a physical interface bound to the Dialer interfac e, or a

physical interface that directly enables DDR.

z Dial string: PSTN telephone num ber or ISDN telephone number

“Dialer Profile”.

z Dialer Profile (Dialer Profiles): developed to meet the needs of various dial

configurations for some common physical interfaces.

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 (integr ated

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 n ot

connected. Only if there are packets to be transferred between them, will DDR be

started and dialup connection established between them to trans fer 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.