Software User's Guide Version 3.3

Using the V.25bis Network Interface

The V.25bis interface allows routers to establish serial connections over switched telephone lines using V.25bis modems. This chapter describes how to use the V.25bis interface. It includes the following sections:

Before You Begin
Configuration Procedures

Note:

You can assign a destination name to a connection list and assign a destination number to each line in the list. When that destination name is called, the numbers in the list are tried one by one until a connection is made or the list is exhausted.

Before You Begin

Before you configure V.25bis on the router, make sure you have the following:

V.25bis modems that support synchronous V.25bis commands and the 1988 ITU/CCITT V.25bis specification.
If your modem does not automatically detect answer originate, you must:
- Configure the modem at one end of the link to originate calls.
- Configure the modem at the other end of the link to answer calls.
- Set up the modem on the answering end to auto-answer.

Configuration Procedures

This section describes how to configure your router for V.25bis. The tasks you need to perform are:

Adding V.25bis addresses
Configuring V.25bis parameters
Adding dial circuits
Configuring dial circuits

Note:

You must restart the router for changes to the V.25bis configuration to take effect.

Adding V.25bis Addresses

You need to add a V.25bis address for each local V.25bis interface as well as for each destination. The V.25bis address includes:

Address Name. The address name is a description of the address. You can use any string of up to 23 printable ASCII characters.

Network Dial Address. Telephone number of the local or destination port. You can enter up to 30 characters that are in the valid format of the connected V.25bis modem. For additional information consult your modem manual.

Note:

The valid character set for telephone numbers as defined by the CCITT and supported by the IBM 2210 includes:

The decimal digits 0 through 9
Colon (:) -- "Wait Tone"
Left-angled bracket (<) --"Pause", used for inserting a fixed delay (dependent on modem) between digit sequences. For example, when going through a PBX or PTN.
Equal (=) -- "Separator 3", which is "for national use." (Consult your modem manual.)
The letter P -- "Dialing to be continued in Pulse mode." (Not supported by some modems.)
The letter T -- "Dialing to be continued in DTMF mode." (Not supported by some modems.)

To add a V.25bis address, enter the add v25-bis-address command at the Config> prompt. For example:

     Config>add v25-bis-address
     Assign address name [1-23] chars []? remote-site-baltimore
     Assign network dial address [1-30 digits][]? 19095551234

Configuring the V.25bis Interface

This section explains how to configure the V.25bis interface. To configure, do the following:

To set up a serial line interface for V.25bis, set the data-link protocol for the serial line interface. From the Config> prompt, use the set data-link v25bis command. For example:
```
    Config>set data-link v25bis
    Interface Number [0]? 2
```
Display the V.25bis Config> prompt by entering the network command followed by the number of the interface. For example:
```
     Config>network 2
     V.25bis Data Link Configuration
     V25bis Config>
```
You can use the list devices command at the Config> prompt to display a list of interface numbers configured on the router.
Use the set local-address command to specify the network address name of the local port. You must enter one of the address names you defined using the add v25bis-address command. For example:
```
     V25bis Config>set local-address
     Local network address name  []? remote-site-baltimore
```

Note:

You must restart the router for configuration changes to take effect.

Optional V.25bis Parameters

The following are optional V.25bis parameters you can set. For a complete description of these commands, see V.25bis Configuration Commands.

You can limit the number of successive calls to an address that is inaccessible or that refuses those calls. To do so, use the set retries-no-answer and the set timeout-no-answer commands.
The set disconnect-timeout command controls the amount of time the router waits to initiate a call after dropping a signal from the previous call.
The set command-delay-timeout command specifies the amount of time the router waits to initiate or answer a call after it turns on DTR.
The set connect-timeout command specifies the number of seconds allowed for a call to be established.
The set duplex command specifies the duplexing mode for the call.
The set encoding command sets the encoding for the call.
When you have finished configuring the interface, you can use the list command to display your configuration.

Adding Dial Circuits

Dial circuits are mapped to V.25bis serial line interfaces. You can map multiple dial circuits to one serial line interface.

To add a dial circuit, use the add device dial-circuit command from the Config> prompt. The software assigns an interface number to each circuit. You will use this number to configure the dial circuit.

Example:

Config>add device dial-circuit
Adding device as interface 6

Note:

Dial circuits default to the Point-to-Point protocol (PPP). You can also set the dial circuit to use Frame Relay (FR) or SDLC.

Configuring Dial Circuits

This section describes how to configure a dial circuit. For a complete description of the dial circuit commands, see Configuring and Monitoring Dial Circuits.
Note: If the encapsulator type is SDLC, the only dial circuit parameter that you can set is the base net number.
To configure the dial circuit, do the following:

Display the Circuit Config> prompt by entering the network command followed by the interface number of the dial circuit. You can use the list devices command at the Config> prompt to display a list of the dial circuits that you added. For example:
```
     Config>network 6
     Circuit configuration
     Circuit Config>
```
Map the dial circuit to a V.25bis interface. The Base net is the V.25bis interface number. For example:
```
     Circuit Config>set net
     Base net for this circuit [0]?  0
```
Specify the address name of the remote router to which the dial circuit will connect. You must use one of the names you defined using the add v25-bis-address command. For example:
```
    Circuit Config>set destination
    Assign destination address name []? newyork
```
Configure the dial circuit to initiate outbound calls only, accept inbound calls only, or both initiate and accept calls.
Use the set calls command. To avoid a conflict if both ends of the link attempt to establish a call at the same time, configure the dial circuit at one end of the link to accept inbound calls only, and configure the dial circuit at the other end of the link to initiate outbound calls only. For example:
```
    Circuit Config>set calls outbound
    Circuit Config>set calls inbound
```
Note: For WAN Restoral operations or another dial-on-demand application, you should set up the circuit for either inbound or outbound calls.
Specify the timeout period for the circuit.
Use the set idle command. If there is no traffic over the circuit for this specified time period, the dial circuit hangs up. To configure the circuit as a dedicated circuit, set the idle timer to zero. To configure the circuit to dial on demand, set the idle timer to a value other than zero. The range is 0 to 65535 and the default is 60 seconds. For example:
```
    Circuit Config>set idle
    Idle timer (seconds, 0 means always active) [60]? 0
```
Note: For WAN Restoral or WAN Reroute operations you must set the idle time to 0.
Optionally, you can delay the time between when a call is established and the initial packet is sent.
Use the set selftest-delay command. Setting a selftest delay can prevent initial packets from being dropped. If your modems take extra time to synchronize, adjust this delay. For example:
```
    Circuit Config>set selftest-delay
    Selftest delay(milli-seconds,0 means no delay)[150]?200
```
Set the inbound address name.
Use the set inbound command. You need to use this command only if you set up the circuit for both inbound and outbound calls and if the router's destination address is different from the destination address that the remote router dials. For example, the numbers would be different if one of the routers must go through a PBX, international, or inter-LATA exchange. For example:
```
    Circuit Config>set inbound
    Assign destination inbound address name []? newyork
```
The inbound address name must match one of the names that you defined using the add v25-bis-address command.
Set the duplexing mode for the circuit using the set duplex command.
Set the encoding mode for the circuit using the set encoding command.
Optionally, you can enter the configuration process for the data-link layer protocol that is running on the dial circuit (PPP or Frame Relay). Use the encapsulator command. For example:
```
Circuit Config>encapsulator
```

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