Core Network Mobility Management

The Core Network Mobility Management in the Release 1 of the OpenEPC project is built mainly on 2 components: the PMIP Local Mobility Anchor (LMA) and the PMIP Mobile Access Gateway (MAG). For providing a smooth start with EPC, the firstly targeted interfaces were those which would allow an easy integration with standard IP clients and procedures, without requiring fully-featured components like an MME, specialized protocols like GTP or complex and multiple interfaces like S4, S12, S6a or S6b. The Release 1 is then centered around the procedures specified in 3GPP TS 23.402 for the S2a reference point. Partially, also S5/S8 and S2b procedures are supported, with more coming up as the project progresses and support for new protocols and components will be added.

1. OpenEPC Release 1 Local Mobility Anchor (LMA)

Central component of the PDN-Gw, as described in  Mobility Support in IPv6 (RFC 3775) and  Proxy Mobile IPv6 (RFC 5213). It's role is to maintain a binding cache for currently connected users and to manage packet routing to and from these user endpoints. The routing is done via tunnels between the PDN-Gw and the ANGws connected to it. It features a MySQL database as a storage back-end, enabling it to store and expose the state. It also performs IP allocation - providing both IPv4 and IPv6 addresses - and interacts with the PCC architecture by relaying Layer 3 attachment and detachment events.

Supported features:

• dual IPv4/IPv6 supported for PMIP signaling
• ability to use various types of tunnels (ipip  RFC2003, sit  RFC4213, ipip6  RFC 2473, ip6ip6  RFC 2473), covering all possible IPv4/IPv6 connectivity combinations.
• binding cache and IP allocation state saved in a MySQL database
• dual IPv4/IPv6 IP address allocation for mobile clients
• modular architecture, enabling the replacement of key components (IP allocation module, Tunnel Control module) with custom implementations

Limitations:

• GRE tunnels are not supported (in development, but not part of Release 1).
• network triggered detachments are not supported for now.

Central component of the ANGw, as described in  Mobility Support in IPv6 (RFC 3775) and  Proxy Mobile IPv6 (RFC 5213. It's role is to maintain a binding update list for currently connected mobile nodes. It handles requests for attachment/detachment and hand-overs between ANGws. It also manages the routing of packets between the PDN-Gw and the user endpoint. Communication with the LMA is established via Proxy Binding Updates and Answers, implementing the PMIP guidelines. It features a MySQL database as a storage back-end, enabling it to store and expose the state.

Supported features:

• dual IPv4/IPv6 supported for PMIP signaling
• ability to use various types of tunnels (ipip  RFC2003, sit  RFC4213, ipip6  RFC 2473, ip6ip6  RFC 2473), covering all possible IPv4/IPv6 connectivity setups
• binding update list stored in a MySQL database
• communication with a modified ISC-DHCP server serving IPv4/IPv6 addresses
• modular architecture, enabling the replacement of key components (Tunnel Control module) with custom implementations

Limitations:

• GRE tunnels are not supported (in development, but not part of Release 1).