3Com 3C892 manual Understanding Multilink PPP, Call Routing While One Call Is Already Connected

Understanding Multilink PPP and BACP/BAP 21

Rob's PC	192
192.168.1.2
		.
		168
				.
				1
				.
				2
Laura's PC
192.168.1.3
				.4
		.1
	.168
	192
			. 1	. 5
		. 168
Buddy's PC	192
192.168.1.4

	Translates PC IP													Internet/Intranet or
					IP address										online service
	addresses to IP
					assigned by ISP
	address assigned									1
								.		.		.
								1				1			1
							6				1
	by ISP						. . .
										6				1
							198		.		.		.
							198					6
									198						ISDN BRI line
					198.6.1.1	Public telephone
Alert PWR ISDN B1	B2	Tx Coll 1 2 3 4	ISDN LAN Modem			network
		LAN STATUS	OfficeConnect™	3 Com

OfficeConnect® ISDN LAN Modem

192.168.1.1

ISDN BRI line

Sally's PC 192.168.1.5

Figure 9 IP Address Translation

Call Routing While One Call Is Already Connected

If the ISDN LAN Modem has established a call to a remote destination, for instance, to an ISP, and the ISDN LAN Modem receives more packets, then the ISDN LAN Modem looks at the Network ID of the packets for proper routing. For example, if the Network ID of the packets matches that of the remote LAN and that connection has not yet been established, then the call is placed and the connection is made. If the Network ID does not match and the call type is an Internet access call, then the packets are routed to the ISP.

Note that the ISDN LAN Modem always calls the first configured ISP. If you have configured a second ISP and want to use that one instead, from the ISDN LAN Modem’s configuration home page go to Workstation Parameters, select your computer, and then associate only the ISP that you want to use.

Understanding

Multilink PPP and

BACP/BAP

What is Multilink PPP?

Multilink PPP is a protocol which combines multiple point-to-point protocol (PPP) connections to form a single high-bandwidth channel. With a BRI line, Multilink

PPPcombines the two 56 Kbps or 64 Kbps ISDN B channels, creating a virtual, single connection of up to 112 Kbps or 128 Kbps.

What is BACP/BAP?

BACP/BAP is used in conjunction with the Multilink PPP feature and is transparent to the user (that is, it will not be visible to you as it occurs in the background). You need not configure this functionality. When Multilink PPP is negotiated, the Bandwidth Allocation Control Protocol (BACP) negotiates with the peer equipment to determine whether the peer supports BAP. If the peer supports BAP