3com NETBuilder SI Manual De Usuario

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All dial-up and leased lines use PPP. If you want to use multiple lines or 
channels to connect to the same destination, you can use Multilink PPP. 
Multilink PPP is especially useful for ISDN, as described in the following 
section. 

ISDN consists of two bearer (B) channels and one delta (D) 

channel. Each B channel can transmit up to 64 Kbps; the D channel 
transmits signaling information about the call to computers at the 
switching system at a rate of 16 Kbps.

With Multilink PPP, you can use both B channels together for a combined 
data rate of 128 Kbps. With PPP, you can use each 64 Kbps B channel 
separately.

You can use packet-switched services with your bridge/router instead of 
dial-up or leased lines to take advantage of high performance for a 
reasonable price. This section describes X.25 and Frame Relay.

An X.25 packet-switched network is defined by the International 

Telecommunications Union (ITU) Recommendation X.25, a global 
standard that began development in the 1970s. The recommendation 

Fractional T1

PPP

CSU/DSU

Up to 24 channels (DS0s) at 64 
Kbps each

Digital Data Service (DDS) PPP

CSU/DSU

Up to 64 Kbps

* Some ISDN lines support up to 56 Kbps per B channel. For more information, contact your ISDN service provider.

Table 4   Dial-Up and Leased Line Services

Table 5   Packet-Switched Services

X.25

POTS

Modem

Up to 56 Kbps

Frame Relay

Leased line

CSU/DSU

Up to 2.048 Mbps

SMDS

Leased line

CSU/DSU

Up to 2.048 Mbps