3Com 3C892 Understanding, Dynamic Bandwidth, Allocation, Multilink PPP Configuration Options

22CHAPTER 2: ISDN LAN MODEM FUNCTIONALITY DESCRIPTION

and agrees to use BAP, then the Bandwidth Allocation Protocol (BAP) negotiates the addition and removal of the second B channel with the peer equipment based on a user-defined threshold. A key advantage of BACP/BAP is that it provides a higher probability of establishing a Multilink PPP call during high traffic conditions by providing a specific telephone number for the second B channel to call.

Multilink PPP Configuration Options

When configuring Multilink PPP, you can choose one of the following options from the ISDN LAN Modem’s Service Provider Parameters window.

■ Use One B Channel

When this option is configured, only one B channel is used to connect to this service provider. Multilink PPP is thereby disabled and BACP/BAP is therefore not used.

■ Use Two B Channels

When this option is configured, both B channels are always used to connect to this service provider, regardless of the amount of traffic over each

B channel. Note that when this option is selected, the DBA feature does not work because both B channels are being used. To use both DBA and Multilink PPP, select the option Add Second B Channel as Required.

■ Add Second B Channel As Required

When this option is configured (referred to as bandwidth on demand) only one

B channel is used to connect to this service provider, and the second

B channel is automatically added only when the amount of traffic on the first

B channel reaches a threshold you define.

	In order for you to use Multilink PPP, the destination you are calling must also
	support Multilink PPP. For example, if you are trying to dial in to the Internet, your
	ISP must also support Multilink PPP in order to successfully place a Multilink PPP
	call. If you attempt to place a Multilink PPP call and the location you are calling
	does not support Multilink PPP, then a single B channel PPP connection is
	established.
Understanding	Dynamic Bandwidth Allocation is used in conjunction with Multilink PPP on
Dynamic Bandwidth	demand (to use DBA, you should choose Add Second B Channel As Required
Allocation	when you configure Bandwidth Allocation). The Dynamic Bandwidth Allocation
	feature allows you to automatically and temporarily remove one of the B channels
	and use it either to place or receive a call (voice or data) without disturbing the
	original call. The only effect on the original call is that it is reduced from a Multilink
	PPP call to the speed of one B channel.
	Once the interrupting call ends, that B channel is automatically returned to the
	Multilink PPP call. Although throughput is reduced while the interrupting call is
	active, the reliability of the Multilink PPP call is maintained.