Creating an IP Addressing Scheme for Callers

Consider creating one or more IP addresses for all incoming calls instead of assigning a unique IP address to each remote user. Dedicated IP addresses are particularly important if the number of potential callers exceeds the number of serial ports and modems on the dial-in server. You can implement a number of different scenarios, depending on your site's needs. Moreover, the scenarios are not mutually exclusive.

Assigning Dynamic IP Addresses to Callers

Dynamic addressing involves the assignment to each caller of the IP address that is defined in /etc/ppp/options.ttyname. Dynamic addressing occurs on a per-serial port basis. When a call arrives over a serial line, the caller receives the IP address in the /etc/ppp/options.ttyname file for the call's serial interface.

For example, suppose a dial-in server has four serial interfaces that provide dial-up service to incoming calls:

• For serial port term/a, create the file /etc/ppp/options.term.a with the following entry:

  :10.1.1.1

  
  

• For serial port term/b, create the file /etc/ppp/options.term.b with the following entry:

  :10.1.1.2

  
  

• For serial port term/c, create the file /etc/ppp/options.term.c with the following entry:

  :10.1.1.3

  
  

• For serial port term/d, create the file /etc/ppp/options.term.d with the following entry:

  :10.1.1.4

  
  

The advantages of dynamic addressing include the following:

• You can track PPP network usage down to the serial port.

• You can assign a minimum number of IP addresses for PPP use.

• You can administer IP filtering in a more simplified fashion.

Assigning Static IP Addresses to Callers

If your site implements PPP authentication, you can assign specific, static IP addresses to individual callers. In this scenario, every time a dial-out machine calls the dial-in server, the caller receives the same IP address.

You implement static addresses in either the pap-secrets or chap-secrets database. Here is a sample /etc/ppp/pap-secrets file that defines static IP addresses.

Here is a sample /etc/ppp/chap-secrets file that defines static IP addresses.

Assigning IP Addresses by sppp Unit Number

If you are using either PAP or CHAP authentication, you can assign IP addresses to callers by the sppp unit number. The next table shows an example of this usage.

The plus sign (+) indicates that the unit number is added to the IP address. Addresses 10.10.111.240 through 10.10.111.255 are assigned to remote users. sppp0 gets IP address 10.10.111.240. sppp1 gets IP address 10.10.111.241, and so on.

Creating PPPoE Tunnels for DSL Support

By using PPPoE, you can provide PPP over high-speed digital services to multiple clients that are using one or more DSL modems. PPPoE implements these services by creating an Ethernet tunnel through three participants, the enterprise, the telephone company, and the service provider.

• For an overview and description of how PPPoE works, see PPPoE Overview.

• For tasks for setting up PPPoE tunnels, see Chapter 30, Setting Up a PPPoE Tunnel (Tasks).

This section contains detailed information about PPPoE commands and files, which is summarized in the next table.

Table 32-8 PPPoE Commands and Configuration Files

Files for Configuring Interfaces for PPPoE

The interfaces that are used at either end of the PPPoE tunnel must be configured before the tunnel can support PPP communications. Use /usr/sbin/sppptun and /etc/ppp/pppoe.if files for this purpose. You must use these tools to configure Ethernet interfaces on all Solaris PPPoE clients and PPPoE access servers.

/etc/ppp/pppoe.if File

The /etc/ppp/pppoe.if file lists the names of all Ethernet interfaces on a host to be used for the PPPoE tunnels. This file is processed during system boot when the interfaces that are listed are plumbed for use in PPPoE tunnels.

You need to explicitly create /etc/ppp/pppoe.if. Type the name of one interface to be configured for PPPoE on each line.

Sample /etc/ppp/pppoe.if File

The following example shows an /etc/ppp/pppoe.if file for a server that offers three interfaces for PPPoE tunnels.

# cat /etc/ppp/pppoe.if hme1 hme2 hme3

PPPoE clients usually have only one interface that is listed in /etc/ppp/pppoe.if.

/usr/sbin/sppptun Command

You can use the /usr/sbin/sppptun command to manually plumb and unplumb the Ethernet interfaces to be used for PPPoE tunnels. By contrast, /etc/ppp/pppoe.if is only read when the system boots. These interfaces should correspond to the interfaces that are listed in /etc/ppp/pppoe.if.

sppptun plumbs the Ethernet interfaces that are used in PPPoE tunnels in a manner that is similar to the ifconfig command. Unlike ifconfig, you must plumb interfaces twice to support PPPoE because two Ethernet protocol numbers are involved.

The basic syntax for sppptun is as follows:

# /usr/sbin/sppptun plumb pppoed device-name device-name:pppoed # /usr/sbin/sppptun plumb pppoe device-name device-name:pppoe

In this syntax, device-name is the name of the device to be plumbed for PPPoE.

The first time that you issue the sppptun command, the discovery protocol pppoed is plumbed on the interface. The second time that you run sppptun, the session protocol pppoe is plumbed. sppptun prints the name of the interface that was just plumbed. You use this name to unplumb the interface, when necessary.

For more information, refer to thesppptun(1M) man page.

Sample sppptun Commands for Administering Interfaces

• The following sample shows how to manually plumb an interface for PPPoE by using /usr/sbin/sppptun.

  ---

  Example 32-1 To plumb an Interface to Support PPPoE

  # /usr/sbin/sppptun plumb pppoed hme0 hme0:pppoed # /dev/sppptun plumb pppoe hme0 hme0:pppoe

  
  

  ---

• This sample shows how to list the interfaces on an access server that was plumbed for PPPoE.

  ---

  Example 32-2 To List All Interfaces on a PPPoE Access Server

  /usr/sbin/sppptun query hme0:pppoe hme0:pppoed hme1:pppoe hme1:pppoed hme2:pppoe hme2:pppoed

  
  

  ---

• This sample shows how to unplumb an interface.

  ---

  Example 32-3 To Unplumb an Interface With a PPPoE Tunnel

  # sppptun unplumb hme0:pppoed # sppptun unplumb hme0:pppoe

  
  

  ---