PPP Over Serial WAN Port

This chapter contains the following information about configuring the SuperStack II Remote Access System (RAS) 1500 to support Point-to-Point Protocol (PPP) over the serial wide area network (WAN) port.

• Overview

• Case Study

• Troubleshooting

• Properly configured network protocols

The RAS 1500 supports a PPP connection over a leased line on its serial port. A leased line is a dedicated line between two sites and is permanently installed rather than a dialed up connection. PPP over the WAN port can connect to another RAS 1500 or any device that supports PPP.

PPP over leased line offers the following benefits:

• Constant connection. Once the connection between the sites is established, the link does not come down unless you issue a command to do so.

• Simple configuration. To prepare a RAS 1500 for leased-line PPP requires little configuration.

• Fast. The RAS 1500 supports speeds of 2.048 Mbps.

Figure 23 shows a typical PPP over leased line setup.

Figure 23 Typical PPP over leased line setup

The RAS 1500 supports the following protocols through the WAN port. There are no settings on the RAS 1500, a different cable is used for each protocol.

• V.35

• RS-232E (V.28)

• RS-422 (V.11, X.21)

• RS-449 (V.11, V.10)

• EIA-530 (V.11, V.10)

• EIA-530A (V.11, V.10)

Before you configure the RAS 1500 for PPP over leased line, do the following:

1 .   Work with the phone company to acquire a leased line between the two sites.

2 .   The leased line attaches to the Channel Service Unit/Data Service Unit (CSU/DSU) at both customer sites.

3 .   The leased line is responsible for providing a clock, either through the Central Office or through the CSU/DSU.

• Connect the "main_office" RAS 1500, to the "branch_office" RAS 1500 using a leased line connection PPP link.

• Authenticate using PAP.

• Idle timeout should be 300 seconds.

• Each office has a functioning RAS 1500.

• Each office has a separate IP network. The main office has 192.112.226.0/C; the branch office has 192.112.227.0/C.

• Use Routing Information Protocol (RIPv1).

The goals can be achieved with either a numbered IP link or an unnumbered link between the sites. Figure 24 shows a numbered link, and Figure 25 shows an unnumbered link.

Figure 24 Numbered PPP over Serial WAN Port Link

Figure 25 Unnumbered PPP over Serial WAN Port Link

To configure the RAS 1500 in the Main Office, perform the following:

If an IP network has been defined, configured, and enabled on the RAS 1500, steps 1 through 3 are not necessary.

1 .   Add an IP network.

add ip network ipnet-1 address 192.112.226.1/C interface rm0/eth:1

2 .   Add a user.

add user branch_office password chicago type network,dial_out

set user branch_office idle_timeout 300

3 .   Configure the user network parameters.

a .   Numbered link

set network user branch_office address_selection specified remote_ip_address 78.0.0.2/A

set network user branch_office ipx disable appletalk disable bridging disable

set network user branch_office send_password boston

b .   Unnumbered link

set network user branch_office address_selection specified remote_ip_address 192.112.227.1/C

set network user branch_office ipx disable appletalk disable bridging disable

set network user branch_office send_password boston

4 .   Configure the user dial-out parameters.

set dial_out user branch_office local_ip_address 78.0.0.1/A

set dial_out user branch_office site type ondemand

5 .   Configure the user routing parameters.

set network user branch_office ip_routing both rip ripv1

6 .   Add the PPP datalink.

add datalink ppp user <username> interface rm0/wan:1

Example:

add datalink ppp user test interface rm0/wan:1

7 .   Configure authentication.

set ppp receive_authentication pap

set system transmit_authentication_name main_office

8 .   Save your work.

save all

To configure the RAS 1500 in the Branch Office, perform the following:

If an IP network has been defined, configured, and enabled on the RAS 1500, steps 1 through 3 are not necessary.

1 .   Add an IP network.

add ip network ipnet-2 address 192.112.227.1/C interface rm0/eth:1

2 .   Add a user.

add user main_office password boston type network,dial_out

set user main_office idle_timeout 300

3 .   Configure the user network parameters.

set network user main _office address_selection specified remote_ip_address 78.0.0.1/A

set network user main _office ipx disable appletalk disable bridging disable

set network user main _office send_password chicago

4 .   Configure the user dial-out parameters.

set dial_out user main _office local_ip_address 78.0.0.2/A

set dial_out user main _office site type ondemand

5 .   Configure the user routing parameters.

set network user main _office ip_routing both rip ripv1

6 .   Configure authentication.

set ppp receive_authentication pap

set system transmit_authentication_name branch_office

7 .   Save your work.

save all

To bring down the connection, issue the following command:

disable datalink ppp interface rm0/wan:1

To view the status of the link, use the list ppp command.

For debugging purposes, view the LCP negotiation, which is part of the PPP negotiation. These negotiations are only visible if the loglevel is set to "verbose" or "debug." You should also check the following:

• Cable type

• Users enabled

• Properly configured network protocols