# Developing AN applications

Use NMS hardware and software with the NMS V5 library functions to create Access Network (AN) applications that perform the following tasks:

- Configure E1 boards.

- Configure up to three HDLC controllers per E1 link on the V5.2 interface.

E1 link locations for HDLC links are application-configurable, but depending on the application requirements, AN applications must set these links to occupy timeslots 16, 15, or 31 on two different E1 links.

- Dynamically add and remove HDLC links required for ISDN over V5.2 support.

- Send and receive HDLC data and error reports.

- Buffer outgoing and incoming messages for each HDLC channel.

- Detect and report the following:

- Loss of frame and loss of signal

- Alarm indications (AIS) and remote alarm indications (RAIs)

- Operations associated with the SA7 framing bit

- Far end block error (FEBE) counters

- Support the lower level switching fabric required by the V5.2 protocol.

- Provide library tracing capabilities.

HDLC device controllers perform the following tasks:

- Dynamically configure, re-configure, and destroy HDLC instances.

- Initialize and reset HDLC instances.

- Activate and deactivate HDLC instances.

- Control the transmission and reception of HDLC frames.

- Perform statistics monitoring.

- Control the transmission of asynchronous events and error reports.

Framer device controllers perform the following tasks:

- Monitor E1 links for alarms and errors.

- Control E1 link statistic reports.

- Configure SA7 bit settings for E1 links.

The NMS V5 library also provides physical layer access to the upper layers of the Aztek AV5 protocol stack. NMS V5 library functions allow applications to perform the following tasks:

- Initialize the software.

- Provision interfaces (for active and standby variants).

- Start and stop interfaces.

- Switch to and from standby variants.

- Add and delete E1 links

- Monitor E1 links through link status and statistics queries.

- Perform HDLC transmit and receive operations such as sending and receiving LAPV frames on HDLC channels.

- Add and delete HDLC channels.

Note: The NMS DLCP software is designed to work with Aztek's AV5 software, but can also be integrated with other third party V5.2 implementation software.