4000 Router Series Layer 2 - WAN Configuration Guide

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Configuring SPID of the ISDN NI protocol

NI protocol used in North America is only applied to BRIs. The ISDN network uses service profile

identification (SPID) to identify different services, and the PBX provides the service (audio, data, or

speech service) to the terminal user according to the SPID. Each B channel corresponds to a SPID.

For the user to proceed with normal calling and disconnection processes after the SPID handshake

interaction, the user must obtain the SPID to interact with the PBX to perform the Layer 3 (Q.931)

initialization after Q.921 successfully establishes the link and before the Q.931 calling processing starts.

SPID information can be obtained through static configuration or dynamic negotiation. The PBX

determines which method to use.

For dynamic negotiation, the ISDN device sends a Q.931 INFORMATION message with an invalid SPID

to the PBX. The PBX replies with a Q.931 INFORMATION message including a valid SPID to the ISDN

device once or multiple times for the device to select a valid SPID. After that, the Layer 3 initialization

starts.

The Layer 3 initialization must be performed for both static configuration methods and dynamic

negotiation methods. The ISDN device sends a Q.931 INFORMATION message with a valid SPID

obtained by either method to the PBX. The PBX replies with a Q.931 INFORMATION message including

a terminal ID information element. The Layer 3 initialization ends.

Configuring SPID parameters for dynamic negotiation

The device uses dynamic negotiation to obtain a SPID by default. The PBX assigns a SPID for the device.

During the dynamic negotiation, if the PBX provides multiple SPIDs to the device, the device selects a SPID

according to the service type of the current configuration. The SPID that simultaneously supports speech

and data services takes precedence by default.

You cannot perform this task during the dynamic negotiation on an ISDN BRI.

To configure SPID parameters for dynamic negotiation:

Ste

Command

Remarks

1. Enter system view.

system-view N/A

2. Enter ISDN BRI

interface view.

interface bri interface-number N/A

3. Set the service type

supported by the

SPID selected by the

device.

isdn spid service [ audio | data |

speech ]

By default, the SPID must simultaneously

support speech and data services.

4. Set the time interval

of timer TSPID on a

BRI.

isdn spid timer seconds

The default is 30 seconds.

The timer TSPID is started when the device

originates a negotiation or initialization

request by sending an INFORMATION

message and waits for a response.

The device resends the INFORMATION

message if no response is received after the

timer TSPID expires.