Configuring DCC·· 1

Overview·· 1

DCC configuration task list 1

Configuring RS-DCC·· 1

Enabling RS-DCC·· 1

Configuring dial authentication for RS-DCC·· 2

Configuring DCC timers and buffer queue length· 2

DCC timers and buffer queue length· 3

Configuration procedure· 3

Displaying and maintaining DCC·· 3

Troubleshooting· 4

Overview

Dial Control Center (DCC) is a routing technology used when devices interconnect through a public switched network, such as a PSTN or an ISDN. It can provide the dial-on-demand service where any two devices dial to set up a connection when data needs transferring instead of setting up a connection before that. When the link becomes idle, DCC automatically disconnects it.

DCC configuration task list

Configuring RS-DCC

In the RS-DCC approach, physical interface configuration is separated from logical configuration for calls and they can be combined dynamically for each call.

When you configure RS-DCC for on-demand dial, configure RS-DCC sets. Each RS-DCC set is an attribute collection containing a dialer interface, dialer interface attributes, and a dialer bundle.

·          For each dialer interface, you can define only one dial string. As this dial string has its own dial attribute set, all calls placed using this dial string use the same DCC attribute parameters (such as dial rate).

·          Each dialer interface can use only one dialer bundle. Each dialer bundle may contain multiple physical interfaces with different priorities, but each of these interfaces can belong to multiple dialer bundles.

Complete these tasks to configure RS-DCC for on-demand calling:

Enabling RS-DCC

Configuring dial authentication for RS-DCC

In RS-DCC, associations between physical interfaces and dialer interfaces are rather flexible. To allow a called party to identify calling parties, configure authentication, either PAP or CHAP.

When you configure dial authentication for RS-DCC, follow these guidelines:

·          H3C recommends configuring either PAP or CHAP authentication on both physical and dialer interfaces at both sending and receiving ends.

·          When PPP encapsulation is enabled on a dialer interface, configure a remote username with the dialer user command for the dialer interface. When DCC decides which dialer interface is used for receiving a call, it compares the remote username gained through PPP negotiation against those assigned to dialer interfaces for a match.

To configure dial authentication for RS-DCC:

Configuring DCC timers and buffer queue length

C-DCC and RS-DCC are available with some optional parameters. Configure them appropriately to improve on-demand dial efficiency.

DCC timers and buffer queue length

You can configure the following parameters on a dialup interface:

·          Link idle-timeout timer—A link idle-timeout timer starts upon setup of a link. When the timer expires, DCC disconnects the link.

·          Holddown timer—A holddown timer starts upon disconnection of a link. The call attempt to bring up this link can be made only after the timer expires, preventing a remote PBX from being overloaded.

·          Wait-carrier timer—Sometimes, the time DCC waits for a connection to be established may vary call by call. To handle this situation, use a wait-carrier timer. A wait-carrier timer starts when a call is placed. If the connection is not established upon expiration of the timer, DCC terminates the call.

·          Buffer queue length—If no connection is available when a dialup interface without a buffer queue receives a packet, it will drop the packet. Configured with a buffer queue, the dialup interface will buffer the packet until a connection is available for packet sending.

Configuration procedure

To configure DCC timers and buffer queue length on a dialup interface:

Displaying and maintaining DCC

Troubleshooting

Symptom 1

DCC dialup connection cannot be set up because the modem does not dial when the device forwards data.

Solution

Check that:

·          The modem and phone cable connections are correct, and the modem initialization process is correct.

·          DCC is enabled on the dialup interface.

·          A dialer number command is available for the packets.

Symptom 2

The remote end cannot be pinged after the modem is connected.

Solution

Check that:

·          The same link layer encapsulation is used at the two ends, and correct PPP parameters are configured for authentication. Use the debugging ppp all command to verify that.

·          A correct IP address is assigned to the dialup interface (physical or dialer interface).

·          DCC is enabled on the dialup interface.

·          The correct dialer-group and dialer-rule commands are configured and associated to make sure that the packets can pass.

·          Use the debugging dialer event and debugging dialer packet commands to locate the problem.