# Link Access Procedure for Frame Relay

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In [wide area network](/source/Wide_area_network) computing, the **Link Access Procedure for Frame Relay** (or **LAPF**) is part of the network's [communications protocol](/source/Communications_protocol) which ensures that frames are error free and executed in the right sequence.

LAPF is formally defined in the [International Telecommunication Union](/source/International_Telecommunication_Union) standard [Q.922](/source/Q.922). It was derived from [IBM](/source/IBM)'s [Synchronous Data Link Control](/source/Synchronous_Data_Link_Control) protocol, which is the layer 2 protocol for IBM's [Systems Network Architecture](/source/Systems_Network_Architecture) developed around 1975. ITU used SDLC as a basis to develop LAPF for the [Frame Relay](/source/Frame_Relay) environment, along with other equivalents: [LAPB](/source/LAPB) for the [X.25](/source/X.25) protocol stack, [LAPM](/source/LAPM) for the [V.42](/source/ITU-T_V.42) protocol, and LAPD for the [ISDN](/source/ISDN) protocol stack.

In Frame Relay [Local Management Interface](/source/Local_Management_Interface) (LMI) messages are carried in a variant of LAPF frames.

LAPF corresponds to the [OSI model](/source/OSI_model) Data Link layer.

## See also

- [Link access procedure](/source/Link_access_procedure)

## External links

- [Cisco Frame Relay documentation](http://www.cisco.com/en/US/docs/internetworking/technology/handbook/Frame-Relay.html)

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Adapted from the Wikipedia article [Link Access Procedure for Frame Relay](https://en.wikipedia.org/wiki/Link_Access_Procedure_for_Frame_Relay) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Link_Access_Procedure_for_Frame_Relay?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.