Specifications

5-3
Cisco AS5x00 Case Study for Basic IP Modem Services
11/24/1999
Section 5 Configuring PPP and Authentication
Configuring LCP Options
Step 2
Verify that the IP address pool was created:
5800-NAS#show ip local pool
Pool Begin End Free In use
addr-pool 172.22.90.2 172.22.90.254 253 0
5800-NAS#
Task 3. Configuring LCP Options
The group-async interface is a template that controls the configuration of all the asynchronous
interfaces in the NAS.
Asynchronous interfaces:

Are lines that can run in PPP mode

Use the same number as its corresponding line

Save you time and configuration file size by configuring the asynchronous interfaces as a
group-async
The client PPP framing must match the Cisco IOS interface. Figure 5-1 shows this concept.
Figure 5-1 Modem Dialup PPP Framing
The following group-async configuration applies to asynchronous interfaces 1/2/00 through 1/10/143:
!
interface Group-Async0
ip unnumbered FastEthernet0/1/0
encapsulation ppp
async mode interactive
ppp authentication chap pap
peer default ip address pool addr-pool
no cdp enable
no ip directed-broadcast
group-range 1/2/00 1/10/143
!
Table 5-1 describes the previous configuration snippet in more detail:
Table 5-1 Interface Group Async Command Descriptions
Command Purpose
ip unnumbered FastEthernet0/1/0
Conserves IP address space by configuring the
asynchronous interfaces as unnumbered.
encapsulation ppp
Enables PPP.
29656
RS-232
Async PPP
Client
modem
Cisco AS5x00
group-async
Client
PC
POTS PRI
PSTN