ADTRAN L128T user manual Bridging

Chapter 1: Understanding ISDN and the Express L128/L128T

Bridging

In Bridge Mode, the Express L128/L128T can communicate with two remote networks at a time. The destination is dialed by setting up a Connection List profile and choosing Dial on the Dial menu. See Configuration/Connection List on page 63 for instructions on setting up a Connection List profile.

During a two B-channel PPP Multilink call, the Express L128T automatically drops one B-channel and provides it to the POTS port when a telephone call is placed or answered. When a POTS telephone call terminates, the Express L128 redials the second B-channel and supplies the bandwidth back to the LAN connection. Since other bandwidth management features are disabled in the factory default configuration, the dialed links remain active until the Hang-upcommand is entered from the Dial menu, terminating the session with the se- lected remote network.

The Connection List described in the next section may be used to automate di- aling and to store additional information specific to the remote site being di- aled (phone numbers, number of B-channels to dial, authentication information, Caller ID, etc.). In addition, to reduce line charges, Demand Di- aling may be enabled to allow idle links to disconnect when not being used .

Simple Demand Bridging may be configured by enabling the Idle Time-Out parameter under the Configuration/ Connection List [1]/Bandwidth/On De- mand option on the Connection List. Setting this parameter to a non-zero val- ue allows a bridge connection to disconnect after the specified number of seconds with no traffic crossing the ISDN link. Bandwidth can be controlled using the Express L128/L128T’s advanced filtering capability. When new traf- fic needs to be transmitted, the Express L128/L128T will run each packet through its Demand filters defined for each Connection List profile. If a packet can pass through the filter, then the numbers for that profile are dialed. In ad- dition, when both B-channels are selected for use, the link may be configured to add/remove the second B-channel based on the amount of traffic crossing the link. The bridged connection is terminated when the Hang-upoption is selected from the Dial menu, but will redial if the demand filter condition is met.

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