In other words, MPLS encapsulations are performed on IP packets entering the MPLS cloud. An MPLS label is a 20-bit value found in the 32-bit MPLS shim header that is wedged between the L2 header and the IP packet.
ATM cells are forwarded within the ATM cloud based on Virtual Path Identifiers/Virtual Circuit Identifiers (VPIs/VCIs), whereas MPLS tagged IP packets are forwarded within the MPLS cloud based on MPLS labels. An MPLS cloud is comparable to an ATM cloud. One quick way to understand MPLS is through an analogy: MPLS to ATM. MPLS goes under the umbrella of data-path virtualization. As MPLS is a huge topic, only its bare necessities are reviewed in this section. Since the various next-generation WAN deployment options involve MPLS and MPLS VPN, before covering these techniques further, it is worthwhile to include a brief MPLS VPN prelude. Tan, in Private Cloud Computing, 2012 MPLS VPN prelude Ryu is comparable to Pox, but still under active development and supports the up-to-date OpenFlow versions. In contrast, industry-oriented implementations, such as Floodlight, Opendaylight, and Faucet, often provide a REST API and are configured via a configuration file in Yet Another Next Generation (YANG) or YAML Ain't Markup Language (YAML) format, rather than actual programming. However, they deliver many examples, which can be modified and adapted to different needs. Both implementations were research-oriented and are now deprecated. The reference controller implementation for the OpenFlow protocol was Nox, which is C++ based, and its sibling Pox, which is Python based. Note that the initial design of the PFCP was defined to support the Control and UPs Separation feature in the EPC. The N2 uses the Stream Control Transmission Protocol (SCTP) to transport the Next Generation Application Protocol (NG-AP) to support CP communication between 5G-AN and 5G-Core.īetween the SM function (i.e., SMF) and UPF over the N4 interface, it is based on Packet Forwarding Control Protocol (PFCP) to allow the SMF to control UPF for the UP data. The N2 interface supports CP signaling between the RAN and 5G core including the scenarios related to UE context management and PDU session/resource management procedures. This includes information related to connection, mobility, and session-related messages to the AMF, which handles cases related to connection and mobility messages, but forwards SM info to SMF. The N1 interface is used by the UE for transmitting nonradio signaling between the UE and AMF/SMF. 5G-AN uses N2 (CP) to interface with 5G-Core where N1 is a transparent interface between 5G-UE with 5G-Core (i.e., carrying NAS signaling). As mentioned earlier, the MM and SM CP functionalities have been reorganized and decoupled into two functionally independent NFs, AMF and SMF, respectively. The CP signaling is transmitted through the Uu, N2, and N11 interfaces. The CP is used to carry the signaling between the UE and the network. Tricci So, in 5G NR and Enhancements, 2022 3.1.3.1 End-to-end protocol stack of 5G control plane based on 3rd Generation Partnership Project access Subscription control checks the administrative rights of the UMTS bearer service user to use the requested service with the specified QoS attributes. It reserves the resources if allocated to the UMTS bearer service. It determines for each UMTS bearer service request whether the required resources can be provided by this entity. Īdmission/capability control maintains information about all available resources of a network entity and about all resources allocated to UMTS bearer services.The translation function performs a conversion between UMTS bearer service attributes and QoS parameters of the external networks service control protocol. It provides all user-plane QoS management functions with the relevant attributes. The service manager coordinates the functions of the control plane for establishing, modifying, and maintaining the service. The control plane QoS management functions include: Control plane QoS management functions support the establishment and modification of a UMTS bearer service by signaling/negotiation with the UMTS external services and by the establishment or modification of all UMTS internal services with the required characteristics.
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