Understanding the Differences Between AMF and MME: A Technical Insight
In mobile network architecture, it’s crucial to comprehend the roles that key functions play in managing user mobility. Two essential components in 4G and 5G networks are the MME (Mobility Management Entity) and the AMF (Access and Mobility Management Function). Although both are responsible for mobility management, they operate in different network generations and have distinct functionalities.
What is the MME?
The MME (Mobility Management Entity) is the core mobility management function in 4G/LTE networks. It is responsible for authenticating users, managing session establishment, and handling mobility control between different cell towers and coverage areas. Additionally, the MME interacts with the SGW (Serving Gateway) for data traffic management and the HSS (Home Subscriber Server) for subscriber authentication.
Key functions of the MME:
- Mobility management for users in LTE networks.
- Session establishment, maintenance, and release.
- Interaction with the SGW for data traffic routing.
- Interaction with the HSS for subscriber authentication.
What is the AMF?
The AMF (Access and Mobility Management Function), on the other hand, is a core network function within 5G (5GC). It performs a similar role to the MME, but in the more flexible and modular 5G architecture. In addition to basic mobility and authentication functions, the AMF handles user registration in the 5G network, routes control messages, and coordinates handovers between coverage areas.
Key functions of the AMF:
- Access and mobility management in 5G networks.
- Maintaining user registration status in the network.
- Coordinating handovers and session transitions between coverage areas.
- Forwarding control messages to other 5GC functions, such as the SMF (Session Management Function).
Comparison Between AMF and MME
| Function | MME (LTE) | AMF (5G) |
|---|---|---|
| Network | LTE (4G) | 5G NR |
| Authentication | Yes, with HSS | Yes, with UDM |
| Session Management | Interacts with SGW for data and mobility | Interacts with SMF for session management |
| Mobility | Controls handovers between LTE towers | Controls handovers, including between 4G and 5G |
| Architecture | Centralized | Modular, with more separation of functions |
| Additional Features | Supports handovers in LTE | Supports inter-RAT handovers and between 5G and LTE |
Command Overview: AMF and MME
Now that we understand the functions and the differences between AMF and MME, let’s explore commands used to query information about each of these functions in a telecommunications network environment.
AMF Command:
hget TermPointToAmf amfName|administrativeState|operationalState|usedIpAddress|ipv4Address1|ipv4Address2
This command returns information about the AMF’s operational status in a 5G network environment. Here’s a breakdown of the parameters:
- TermPointToAmf: Refers to the termination point related to the AMF.
- amfName: The name of the AMF instance.
- administrativeState: The administrative state of the AMF (unlocked or locked).
- operationalState: The operational state indicating if the AMF is enabled or disabled.
- usedIpAddress: The IP address currently used by the AMF instance.
- ipv4Address1 and ipv4Address2: Primary and secondary IPv4 addresses associated with the AMF.
MME Command:
hget TermPointToMme administrativeState|ipAddress|mmeCodeListLTERelated|operationalState|usedIpAddress
This command retrieves information about the MME in an LTE network. Let’s detail the parameters:
- TermPointToMme: Refers to the termination point of the MME function.
- administrativeState: Indicates whether the MME is unlocked or locked for operation.
- ipAddress: The IP address of the MME.
- mmeCodeListLTERelated: List of MME codes associated with LTE areas.
- operationalState: The operational state of the MME (enabled or disabled).
- usedIpAddress: The IP currently being used for communication with the MME.
Application Example
If you are monitoring both 5G and LTE networks, these commands are vital for checking the operational status of components such as the AMF and MME. For instance, the AMF in 5G may be configured with multiple IP addresses to handle complex handovers, while the MME in LTE centralizes mobility management between different cell towers.
