3Com NETBuilder SI, Using Manual

Page: 26 / 212

26 C
HAPTER
2: U
SING THE
B
RIDGE
/R
OUTER IN
Y
OUR
N
ETWORK
Using PPP on Dial-Up and Leased Lines
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 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.
Some ISDN lines support up to 56 Kbps per B channel. For more
information, contact your ISDN service provider.
Using Packet-Switched Network Services
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.
X.25 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
Telco Line Protocol
Serial Device (Required
on Flex-WAN Serial Ports) Data Transfer Rate
Table 5 Packet-Switched Services
Packet-Switched
Services/Protocol
Telco Line
Serial Device (Required on
Flex-WAN Serial Ports)
Data Transfer Rate
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