Architecture
A network function (NF) consists of the following layers as part of the cloud native architecture:
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Protocol Layer
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Service Layer
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Datastore Layer
The layers in AMF are as follows:
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Protocol Layer—NGAP/NAS over SCTP transport and SBA over REST/HTTP transport
Example: AMF-protocol and AMF REST-EP
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Service Layer—Business logic of AMF functionality
Example: AMF-service pod
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Data Store Layer—Supports session storage
Example: CDL
The management entities Etcd, Cache pod, and NodeMgr provide services to the Protocol Layer, Service Layer, and Data Store Layer functionalities.
The following figure explains the Architecture of Multiple AMF instances.

The CDL is deployed as an independent entity which acts as a session store for all the instances of AMF during AMF scaling. Each AMF instance performs the following:
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Uses the common CDL for session store.
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Contains all the elements of AMF deployment.
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Doesn't interact with another AMF instance.
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Registers with NRF service endpoint on instantiation, and deregisters the service endpoint on moving out of service.
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Embeds its instance ID as a pointer in GUAMI identity.
The gNBs have a mesh connectivity with all the instances of AMF. The SMF and other network elements discover the AMF instances through the NRF.
The CDL can be configured with slice name as AMF to store the AMF sessions. The AMF instance performs the following:
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AMF instance provide instance ID by enhansing the existing session gRPC APIs of CDL or using session-related CDL gRPC APIs..
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Uses the slice name as AMF for session store with CDL.
The CDL exposes the gRPC API to register or deregister notification URI. The AMF instance uses gRPC API to provide the notification URI details to CDL.
The CDL searches for the notification URI in session lookup with instance ID. If the notification URI fails, the CDL picks another URI from the list in round robin.