
Configuring Dial Services
3-6 114062 Rev. A
Asynchronous PPP
Asynchronous PPP provides communication over asynchronous interfaces
(Figure 3-4) on the AN
®
, ASN™ (using the Dual Sync Net Module); BLN
®
and
BCN
®
(using the Octal Sync Net Module). There are several advantages to
asynchronous communications:
• Low cost - Analog lines are less costly than high-speed digital lines.
Asynchronous modems are less expensive than synchronous modems.
Additionally, you can also dial directly into the router without using a
terminal server and other port-concentration devices.
• Best use of router hardware - You can use an unused serial port on the router
for a dial-up application.
• Availability of lines - Analog lines are available in most locations, enabling
you to dial in from any remote location.
• Throughput - With the V.34 standard, throughput for asynchronous modems is
28.8 Kb/s. Using the V.42bis compression standard, throughput can be higher.
Figure 3-4. Using Asynchronous PPP Across Dial Connections
Using low-cost asynchronous modems makes asynchronous PPP ideal for
customers with small networks that are trying to lower expenses. All three dial
services can use asynchronous PPP for router-to-router connections. Only
dial-on-demand offers support for a router calling a terminal server using
asynchronous PPP.
MODEM
DS0028A
MODEM
MODEM
PSTN
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