Patent Application
20220007251
Embodiments of the invention relate to the field of 5th Generation (5G) mobile communication technology and more specifically, to a method and system for using location identifier separation protocol (LISP) to enable a distributed user plane function architecture to improve efficiency in a 5G network by eliminating inefficiency related to the use of anchor points and further methods for efficiently managing loss handover of user equipment between attachment points.
Referring to
The 5GC 115 and its components are responsible for enabling communication between the UE 101 and other devices both internal and external to the cellular communication system. The 5GC 115 includes a user plane function (UPF) 105, a session management function (SMF) 107, an access and mobility management function (AMF) 109 and similar components. Additional components are part of the 5GC 115, but the components with less relevance to the handling of the UE 101 and its mobility have been excluded for clarity and to simplify the representation. The UE 101 may change the gNodeB 103 through which it communicates with the network as it moves about geographically. The AMF 109, UPF 105 and SMF 107 coordinate to facilitate this mobility of the UE 101 without interruption to any ongoing telecommunication session of the UE 101.
The AMF 109 is a control node that, among other duties, is responsible for connection and mobility management tasks. The UE 101 sends connection, mobility, and session information to the AMF 109, which manages the connection and mobility related tasks. The SMF handles session management for the UE 101.
The UPF 105 provides anchor points for a UE 101 enabling various types of transitions that facilitate the mobility of the UE 101 without the UE losing connections with other devices. The UPF 105 routes and forwards data to and from the UE 101 while functioning as a mobility anchor point for the UE 101 handovers between gNodeBs 103 and between 5G, long term evolution (LTE) and other 3GPP technologies. The UPF 105 also provides connectivity between the UE 101 and external data packet networks by being a fixed anchor point that offers the UE's Internet Protocol (IP) address into a routable packet network.
As shown in the example simplified network of
In one embodiment, a method is implemented by a network device in a cellular communication network, the method to improve handover processing by a source tunnel router (TR) where the source TR forwards traffic destined for a user equipment (UE) that is transferring its connection to a target gNodeB, a target user plane function (UPF) and a target TR to enable mobility within the cellular communication network without anchor points. The method includes receiving a routing locator (RLOC) of the target TR connected to the target UPF and the target gNodeB from a session management function (SMF), redirecting traffic with an endpoint identifier (EID) of the UE to the target TR, receiving a release message from the SMF, and removing state for the EID of the UE.
In another embodiment, a method is implemented by a network device in a cellular communication network, the method to improve handover processing by a target TR and target gNodeB where the target TR and target gNodeB relay traffic between a UE and other devices connected to the cellular communication network to enable mobility within the cellular communication network without anchor points. The method includes receiving redirected traffic for the UE from a source TR, receiving upstream traffic from the UE, forwarding the upstream traffic to a correspondent, and sending an update to a location identifier separation protocol (LISP) mapping server (MS) indicating an EID to the target TR identified by RLOC mapping.
In a further embodiment, a network device in a cellular communication network implements a method to improve handover processing by a source TR where the source TR forwards traffic destined for a UE that is transferring its connection to a target gNodeB, a target UPF and a target TR to enable mobility within the cellular communication network without anchor points. The network device includes a non-transitory computer-readable storage medium having stored therein a handover manager, and a processor coupled to the non-transitory computer-readable storage medium, the processor to execute the handover manager, the handover manager to receive a RLOC of the target TR connected to the target UPF and the target gNodeB from a SMF, to redirect traffic with an EID of the UE to the target TR, to receive a release message from the SMF, and to remove state for the ED of the UE.
In one embodiment, a network device in a cellular communication network implements a method to improve handover processing by a target TR and target gNodeB where the target TR and target gNodeB relay traffic between a UE and other devices connected to the cellular communication network to enable mobility within the cellular communication network without anchor points. The network device includes a non-transitory computer-readable medium having stored therein a handover manager, and a processor coupled to the non-transitory computer-readable medium, the processor to execute the handover manager, the handover manager to receive redirected traffic for the UE from a source TR, to receive upstream traffic from the UE, to forward the upstream traffic to a correspondent, and to send an update to a LISP MS indicating an ED to the target TR identified by RLOC mapping.
The invention may best be understood by referring to the following description and accompanying drawings that are used to illustrate embodiments of the invention. In the drawings:
The following description sets forth methods and system for improving the efficiency of bandwidth utilization in 5th Generation cellular communication architecture networks. More specifically, the embodiments provide a method and system for using location identifier separation protocol (LISP) to improve efficiency in a 5G network by eliminating inefficiency related to the use of anchor points. The 5G architecture and the geographic placement of its components is driven by both technical and business considerations and requires specific functionalities and functional distributions to be carried forward in any update to the architecture. The embodiments provide improved efficiency while preserving the key functionalities of the 5G architecture. The embodiments further build on this architecture to improve the efficiency and reliability of the handover process when a user equipment (UE) transitions from one attachment point in the network to another attachment point. These handover processes include the use of filters for managing traffic forwarding and similar processes.
The specific inefficiencies in the 5G network architecture that are addressed include the functions of the user plane functions (UPF) when serving as anchor points. The embodiments utilize identifiers/locator separation and mapping system technology to enable separation of mobility support from other session functions and the distribution of the session functions closer to the edge. Existing mobility components of 5G networks have an inherent inefficiency in that they use tunneling from an “anchor point” to the UE. Such solutions also have a defined architecture that is motivated by both technical and business concerns which require specific functionalities and functional distributions to be carried forward in any next generation mobility architecture. The embodiments eliminate the bandwidth inefficiency of anchor points while preserving the key functionalities and entity relationships embodied in the 5G network architecture.
In the following description, numerous specific details such as logic implementations, opcodes, means to specify operands, resource partitioning/sharing/duplication implementations, types and interrelationships of system components, and logic partitioning/integration choices are set forth in order to provide a more thorough understanding of the present invention. It will be appreciated, however, by one skilled in the art that the invention may be practiced without such specific details. In other instances, control structures, gate level circuits and full software instruction sequences have not been shown in detail in order not to obscure the invention. Those of ordinary skill in the art, with the included descriptions, will be able to implement appropriate functionality without undue experimentation.
References in the specification to “one embodiment,” “an embodiment,” “an example embodiment,” etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.
Bracketed text and blocks with dashed borders (e.g., large dashes, small dashes, dot-dash, and dots) may be used herein to illustrate optional operations that add additional features to embodiments of the invention. However, such notation should not be taken to mean that these are the only options or optional operations, and/or that blocks with solid borders are not optional in certain embodiments of the invention.
In the following description and claims, the terms “coupled” and “connected,” along with their derivatives, may be used. It should be understood that these terms are not intended as synonyms for each other. “Coupled” is used to indicate that two or more elements, which may or may not be in direct physical or electrical contact with each other, co-operate or interact with each other. “Connected” is used to indicate the establishment of communication between two or more elements that are coupled with each other.
An electronic device stores and transmits (internally and/or with other electronic devices over a network) code (which is composed of software instructions and which is sometimes referred to as computer program code or a computer program) and/or data using machine-readable media (also called computer-readable media), such as machine-readable storage media (e.g., magnetic disks, optical disks, read only memory (ROM), flash memory devices, phase change memory) and machine-readable transmission media (also called a carrier) (e.g., electrical, optical, radio, acoustical or other form of propagated signals—such as carrier waves, infrared signals). Thus, an electronic device (e.g., a computer) includes hardware and software, such as a set of one or more processors coupled to one or more machine-readable storage media to store code for execution on the set of processors and/or to store data. For instance, an electronic device may include non-volatile memory containing the code since the non-volatile memory can persist code/data even when the electronic device is turned off (when power is removed), and while the electronic device is turned on that part of the code that is to be executed by the processor(s) of that electronic device is typically copied from the slower non-volatile memory into volatile memory (e.g., dynamic random access memory (DRAM), static random access memory (SRAM)) of that electronic device. Typical electronic devices also include a set or one or more physical network interface(s) to establish network connections (to transmit and/or receive code and/or data using propagating signals) with other electronic devices. One or more parts of an embodiment of the invention may be implemented using different combinations of software, firmware, and/or hardware.
A network device (ND) is an electronic device that communicatively interconnects other electronic devices on the network (e.g., other network devices, end-user devices). Some network devices are “multiple services network devices” that provide support for multiple networking functions (e.g., routing, bridging, switching, Layer 2 aggregation, session border control, Quality of Service, and/or subscriber management), and/or provide support for multiple application services (e.g., data, voice, and video).
LISP is routing technology that provides alternate semantics for Internet Protocol (IP) addressing. This is achieved via the tunneling of identity information, i.e., endpoint identifier (EID), between tunnel routers identified by routing locators (RLOCs). The on-the-wire format is a variation of IP in IP tunneling with simply different semantics associated with the IP addresses located at different points in the stack. Each of these values, the EID and RLOC, have separate address or numbering spaces. Splitting EID and RLOC enables a device to change locations within a LISP network without the identity of the device changing and therefore associated session state (e.g. transmission control protocol (TCP) or IP security (IPSEC)) remains valid independent of the EID's actual point of attachment to LISP network.
The embodiments utilize LISP to avoid the limitations of anchor points in the 5G network architecture. The UPF in the 5G network architecture act as anchor points that also implement specific functionalities not easily dispensed with as they address business and regulatory requirements. The UPF, which acts as a session anchor point for a given subscriber session, normally has an invariant point in the network. The 5G network architecture has split the anchor point into UPF and SMF, where the UPF is the user plane component and the SMF is the control plane component. The embodiments take advantage of the control plane location being invariant and hide how the user plane is handled by having the location of the UPF functionality follow the UE. For example, the UPF session “state” associated with a UE is co-located with the gNodeB that the UE is currently attached to and if the UE changes its attachment point to the network, the location of the UPF session state and functionality will also be moved to the new attachment point. The embodiments use LISP to “hide” the user plane mobility component from peers in the architecture that are not architected for peer mobility. Key elements of the embodiments include connectivity between a distributed UPF in a visited network and a UPF in a home network (home routed traffic in a roaming scenario), and connectivity between a correspondent and a distributed UPF in a home network (non-roaming case). Although the data plane portion of the UPF associated with a specific UE will follow the UE, the control component appears to peers as geographically pinned entity, which replicates the semantics of how a 3GPP network works today. The embodiments are able to be implemented with no negative impacts on the scaling of networks, or the surrounding network functions. All non-UP interfaces from the UPF (legal intercept, policy etc.) are aggregated by the SMF. The embodiments provide a tunnel router (TR) that participates in 5G procedures and is closely linked to the UPF. The UPF and TR are both controlled entities by the SMF and linked. The UPF and TR can be a single entity or broken out as two to simplify mapping between 5G concepts and LISP concepts.
In this example, functions of the UPF 105 are distributed. Distributed refers to the traditional function that was served by an anchor point being delegated to the LISP system, and the policy and forwarding aspects of the UPF itself being moved adjacent to the UE's point of attachment to the network, such that the state associated with stateful functions and session management are required to “follow” the UE when it changed point of attachment to the network. However, one skilled in the art would understand that this configuration is provided by way of example and not limitation. The distribution of the functions of the UPF 105 in combination with the use of LISP can be utilized in other configurations where different permutations of the functions are distributed. Examples illustrating some of the variations are described herein below with reference to
Returning to the discussion of
The distributed UPFs 105 can be instantiated at each gNodeB with a logically separate instance for each connected UE 101. Thus, the state and similar configuration are specific to the UE 101 and can be transferred or shared with other instances located at other gNodeBs to facilitate handover operations.
A UE 101 served by a home network 117 is shown. The UE 101 is connected to a source gNodeB 103 that may be co-located with UPF 105 as well as a TR 151. The N2 interface is utilized to communicate control plane information between the source gNodeB 103 and the AMF 109. Similar control exchange occurs between other 5GC components (not illustrated) as well as between the SMF 107 and the AMF 109.
When the UE 101 sets up a protocol data unit (PDU) session it will either be directly connected to its home network or roaming. During the course of control exchange the SMF 107 will select the UPF to serve the UE 101 for the requested session. For a directly connected UE the traffic is eligible for local breakout using LISP, the selected UPF 105 will be collocated with the gNodeB 103.
LISP routing (thick solid line) is used to send the user plane traffic across the 5GC from an ingress TR 151 to an egress TR 153 to enable communication between the UE 101 and the correspondent 113. A TR serves as an ingress or egress TR relative to the direction of data traffic such that a given TR is an ingress TR where traffic is being tunneled to be forwarded to the egress TR and an egress TR when it receives traffic from the ingress TR. In the event of a handover from a source gNodeB 103 to a target gNodeB 121, control plane exchange is utilized to coordinate the transfer or synchronization of state from the source gNodeB 103, UPF 105 to the target gNodeB 121, and target UPF 135.
In the example, the TR 151 co-located with the UPF 105 determines the RLOC serving the correspondent, which may be the egress TR 153. The RLOC may be determined using the destination EID from the data traffic by contacting the LISP MR 145. After a transfer of the UE 101 to a target gNodeB 121, the local instance of the UPF 135 will similarly use the destination EID to forward the traffic via the local TR 137 to the egress TR 153 without interruption.
The operations in the flow diagrams will be described with reference to the exemplary embodiments of the other figures. However, it should be understood that the operations of the flow diagrams can be performed by embodiments of the invention other than those discussed with reference to the other figures, and the embodiments of the invention discussed with reference to these other figures can perform operations different than those discussed with reference to the flow diagrams.
The process of the TR begins in response to the receiving of traffic originating at the UE or similar source (Block 501). The traffic may have passed through the UPF. The TR examines the packet header, which is a native header (e.g., an IP header) and from the header information determines the correspondent EID from the packet header (Block 503). If the TR has not already resolved the EID to an RLOC, it does so by querying the LISP MR or similar service to determine the RLOC of the egress TR for the correspondent (Block 505).
The received packet is then encapsulated in a LISP packet where the LISP header is added to the received packet, which is then encapsulated in an IP packet addressed to the RLOC of the egress TR (Block 507). The encapsulated packet can then be forwarded over the core network toward the egress TR (Block 509). The egress TR removes the LISP encapsulation and forwards the packet on to the correspondent on the basis of the EID in the decapsulated packet.
The embodiments have been described with an example of a LISP domain that corresponds to a single SMF serving area. This would need to be logically true for the life of a PDU session as the SMF would coordinate state migration between the distributed set of UPFs as well as collection of session telemetry. In further embodiments, a tracking area could be instantiated as a subset of the LISP domain by the SMF or AMF. In further embodiments, additional 5GC components could be distributed and co-located with the UPF at the gNodeB. As long as an EID of the UE maps to a correct RLOC for the gNodeB, the associated components in a distributed architecture are reachable via the same RLOC, thus there is a 1:1 correspondence between the gNodeBs and any distributed components. The distributed components are instanced on a per UE basis.
However, in the architecture of the embodiments herein, the mobility as a function moves from in front of the UPF to behind it. In other words, the TRs play a role in the mobility before the traffic reaches the distributed UPF, thus, the TRs must play a role in signaling with the UE and gNodeB regarding the handover and must assume the role of coordinating between the source TR and the target TR to make handover hitless. As shown on the right, there are multiple ingress TRs (ITRs) that enable communication with various correspondents.
The handoff is considered “break before make.” The handoff results in a simplification of the UE in that it is not required to maintain multiple radio connections simultaneously, but instead places additional requirements on the network. 5G procedures such as X2 assisted handoff are designed to mitigate the effects of this, however as specified would be inadequate to deal with LISP as a mobility mechanism. The embodiments are expanded to support seamless handoff between TRs, to provide the function that 5G does (X2 handover as an exemplar). At the same time, the expanded support does not rely on the current 5G architectures inefficiencies in the form of anchor points, and bearer setup. The embodiments include extensions to LISP operation to permit a lossless handoff and to permit coordination of LISP TRs with 5G compatible handoff processes.
In a 5G handoff a handover request has knowledge of the source and target gNodeBs. With knowledge of the target gNodeB, the TR associated with the source gNodeB can use the LISP mapping system to resolve the target TR RLOC and can then coordinate the handoff with it and be able to redirect traffic sent prior to synchronization of other systems with the new EID/RLOC binding. This involves additional messaging, including example message types and processes as described further herein below.
The embodiments seek to provide a handoff process that minimizes loss, buffering and blocking of traffic. The embodiments include a handoff process that may involve some traffic being buffered when no connectivity exists from the source TR to the UE and from the UE to the target TR. Buffering at the UE of upstream traffic, during the period that the UE is changing connectivity from the source gNodeB to the target gNodeB, is not problematic as it is the end-system performing the buffering, not an intermediate system, and therefore is not required to deal with packets in flight. To minimize blocking/buffering, the source TR maintains communication with the UE until the moment the UE disconnects. When the UE disconnects, the source TR will immediately start redirecting traffic to the target TR. The handover process involves an exchange of information or ‘handshake’ that is designed such that the source TR and target TR have a priori knowledge of the intended handover sequence. The target TR thereby can expect traffic related to the handover process and so it does not simply silently discard it.
The embodiments provide a trigger for updating the LISP mapping system. The trigger encompasses a “connect” at the target TR, which fits the model of the TR performing the update and is also the RLOC now associated with the ED. The connect can be considered a trigger for a reoptimization process where the dogleg route far_end_correspondents->source_TR->target_TR can be simplified to far_end_correspondents->target_TR.
The handover (HO) decision is made with the 5GC network whereby the target gNodeB that will subsequently serve the UE is identified. When the gNodeBs and UPFs received a notification of the initiation of mobility, it triggers the associated TRs to start the processes shown in
The diagrams of
As illustrated in
The SMF sends the RLOC of the target UPF/TR to the source UPF/TR for handover and redirection of the downstream traffic to the target UPF/TR (Block 1201). The source TR then redirects UE EID destined downstream traffic to the target TR (Blocks 1203 and 1301) once the UE has disconnected. The source TR redirects the UE EID destined downstream traffic by overwriting the RLOC in the received downstream traffic. When the UE connects to the target gNodeB, the target gNodeB sends a path switch message to the AMF, which is relayed to the SMF. The path switch message is an indication that the source UPF session can be taken down after a slight delay. The UE starts sending upstream data via the target UPF/TR (Block 1303). The upstream data traffic is forwarded toward its destination (Block 1305). The target TR, after seeing the UE EID from upstream traffic of the UE, sends an EID/RLOC binding update to LISP Mapping Server (Block 1309).
In parallel, any buffered traffic from the source UPF is sent to the UE (Block 1307). The buffered traffic may include an end marker to signal a completion of the sending of the buffered traffic. The LISP mapping system updates EID/RLOC binding for the correspondent TRs. After receiving the updated bindings, the correspondent TRs direct traffic for the UE using the RLOC of the target TR. The SMF then directs the source UPF/TR to release any session resources associated with the UE (Block 1205). The source UPF/TR responds by removing state related to the UE EID (Block 1207).
The embodiments can utilize a set of messages for the gNodeB to coordinate with the LISP system and architecture as set forth in the example of Table I:
These messages are for a client system to inform the LISP system of pending handoff and for the LISP system to perform the associated inter-TR coordination that is required to facilitate the handover.
The handover process of the embodiments can be utilized with a variety of similar architectures and has been provided by way of example and not limitation. As long as the EID of the UE maps to the correct RLOC for the attached TR, the associated UPF in a distributed architecture are also reachable via the same RLOC. Although in the simplest case there is a 1:1 correspondence between the gNodeB and any UPFs, the system can be expanded to incorporate more complex cases using the same principles.
The embodiments of this handover process provide various advantages over the art. By using LISP, the embodiments get the benefit of shortest path forwarding for mobility management. Coordinating knowledge of pending handover with LISP permits a redirect of traffic from the source egress TR to the target egress TR via the source ingress TR once the UE is no longer reachable from the source TR, and in the process of connecting with the target TR. Informing the target egress TR of a pending handover permits it to receive and buffer traffic for an EID prior to re-attachment of the EID to the network eliminating loss. Eliminating the concept of bearers (which manifest themselves as differentiated services code points (DSCPs)) permits significant simplification of the handover process. These processes collectively mitigate the effects of a “break before make” style of mobility.
Two of the exemplary ND implementations in
The special-purpose network device 1402 includes networking hardware 1410 comprising compute resource(s) 1412 (which typically include a set of one or more processors), forwarding resource(s) 1414 (which typically include one or more ASICs and/or network processors), and physical network interfaces (NIs) 1416 (sometimes called physical ports), as well as non-transitory machine-readable storage media 1418 having stored therein networking software 1414. A physical NI is hardware in a ND through which a network connection (e.g., wirelessly through a wireless network interface controller (WNIC) or through plugging in a cable to a physical port connected to a network interface controller (NIC)) is made, such as those shown by the connectivity between NDs 1400A-H. During operation, the networking software 1420 may be executed by the networking hardware 1410 to instantiate a set of one or more networking software instance(s) 1422. Each of the networking software instance(s) 1422, and that part of the networking hardware 1410 that executes that network software instance (be it hardware dedicated to that networking software instance and/or time slices of hardware temporally shared by that networking software instance with others of the networking software instance(s) 1422), form a separate virtual network element 1430A-R. Each of the virtual network element(s) (VNEs) 1430A-R includes a control communication and configuration module 1432A-R (sometimes referred to as a local control module or control communication module) and forwarding table(s) 1434A-R, such that a given virtual network element (e.g., 1430A) includes the control communication and configuration module (e.g., 1432A), a set of one or more forwarding table(s) (e.g., 1434A), and that portion of the networking hardware 1410 that executes the virtual network element (e.g., 1430A).
The special-purpose network device 1402 is often physically and/or logically considered to include: 1) a ND control plane 1424 (sometimes referred to as a control plane) comprising the compute resource(s) 1412 that execute the control communication and configuration module(s) 1432A-R; and 2) a ND forwarding plane 1426 (sometimes referred to as a forwarding plane, a user plane, or a media plane) comprising the forwarding resource(s) 1414 that utilize the forwarding table(s) 1434A-R and the physical NIs 1416. By way of example, where the ND is a router (or is implementing routing functionality), the ND control plane 1424 (the compute resource(s) 1412 executing the control communication and configuration module(s) 1432A-R) is typically responsible for participating in controlling how data (e.g., packets) is to be routed (e.g., the next hop for the data and the outgoing physical NI for that data) and storing that routing information in the forwarding table(s) 1434A-R, and the ND forwarding plane 1426 is responsible for receiving that data on the physical NIs 1416 and forwarding that data out the appropriate ones of the physical NIs 1416 based on the forwarding table(s) 1434A-R.
Returning to
The instantiation of the one or more sets of one or more applications 1464A-R, as well as virtualization if implemented, are collectively referred to as software instance(s) 1452. Each set of applications 1464A-R, corresponding virtualization construct (e.g., instance 1462A-R) if implemented, and that part of the hardware 1440 that executes them (be it hardware dedicated to that execution and/or time slices of hardware temporally shared), forms a separate virtual network element(s) 1460A-R. The applications 1464A-R may include a handover manager 1465A-R that may encompass the components of a distributed user plane function, tunnel routers and similar components and processes as described herein, in particular to the processes describe with reference to
The virtual network element(s) 1460A-R perform similar functionality to the virtual network element(s) 1430A-R—e.g., similar to the control communication and configuration module(s) 1432A and forwarding table(s) 1434A (this virtualization of the hardware 1440 is sometimes referred to as network function virtualization (NFV)). Thus, NFV may be used to consolidate many network equipment types onto industry standard high-volume server hardware, physical switches, and physical storage, which could be located in Data centers, NDs, and customer premise equipment (CPE). While embodiments of the invention are illustrated with each instance 1462A-R corresponding to one VNE 1460A-R, alternative embodiments may implement this correspondence at a finer level granularity (e.g., line card virtual machines virtualize line cards, control card virtual machine virtualize control cards, etc.); it should be understood that the techniques described herein with reference to a correspondence of instances 1462A-R to VNEs also apply to embodiments where such a finer level of granularity and/or unikernels are used.
In certain embodiments, the virtualization layer 1454 includes a virtual switch that provides similar forwarding services as a physical Ethernet switch. Specifically, this virtual switch forwards traffic between instances 1462A-R and the NIC(s) 1444, as well as optionally between the instances 1462A-R; in addition, this virtual switch may enforce network isolation between the VNEs 1460A-R that by policy are not permitted to communicate with each other (e.g., by honoring virtual local area networks (VLANs)).
The third exemplary ND implementation in
Regardless of the above exemplary implementations of an ND, when a single one of multiple VNEs implemented by an ND is being considered (e.g., only one of the VNEs is part of a given virtual network) or where only a single VNE is currently being implemented by an ND, the shortened term network element (NE) is sometimes used to refer to that VNE. Also, in all of the above exemplary implementations, each of the VNEs (e.g., VNE(s) 1430A-R, VNEs 1460A-R, and those in the hybrid network device 1406) receives data on the physical NIs (e.g., 1416, 1446) and forwards that data out the appropriate ones of the physical NIs (e.g., 1416, 1446). For example, a VNE implementing IP router functionality forwards IP packets on the basis of some of the IP header information in the IP packet; where IP header information includes source IP address, destination IP address, source port, destination port (where “source port” and “destination port” refer herein to protocol ports, as opposed to physical ports of a ND), transport protocol (e.g., user datagram protocol (UDP), Transmission Control Protocol (TCP), and differentiated services code point (DSCP) values.
The NDs of
A virtual network is a logical abstraction of a physical network (such as that in
A network virtualization edge (NVE) sits at the edge of the underlay network and participates in implementing the network virtualization; the network-facing side of the NVE uses the underlay network to tunnel frames to and from other NVEs; the outward-facing side of the NVE sends and receives data to and from systems outside the network. A virtual network instance (VNI) is a specific instance of a virtual network on an NVE (e.g., a NE/VNE on an ND, a part of a NE/VNE on a ND where that NE/VNE is divided into multiple VNEs through emulation); one or more VNIs can be instantiated on an NVE (e.g., as different VNEs on an ND). A virtual access point (VAP) is a logical connection point on the NVE for connecting external systems to a virtual network; a VAP can be physical or virtual ports identified through logical interface identifiers (e.g., a VLAN ID).
Examples of network services include: 1) an Ethernet LAN emulation service (an Ethernet-based multipoint service similar to an Internet Engineering Task Force (IETF) Multiprotocol Label Switching (MPLS) or Ethernet VPN (EVPN) service) in which external systems are interconnected across the network by a LAN environment over the underlay network (e.g., an NVE provides separate L2 VNIs (virtual switching instances) for different such virtual networks, and L3 (e.g., IP/MPLS) tunneling encapsulation across the underlay network); and 2) a virtualized IP forwarding service (similar to IETF IP VPN (e.g., Border Gateway Protocol (BGP)/MPLS IPVPN) from a service definition perspective) in which external systems are interconnected across the network by an L3 environment over the underlay network (e.g., an NVE provides separate L3 VNIs (forwarding and routing instances) for different such virtual networks, and L3 (e.g., IP/MPLS) tunneling encapsulation across the underlay network)). Network services may also include quality of service capabilities (e.g., traffic classification marking, traffic conditioning and scheduling), security capabilities (e.g., filters to protect customer premises from network—originated attacks, to avoid malformed route announcements), and management capabilities (e.g., full detection and processing).
For example, where the special-purpose network device 1402 is used, the control communication and configuration module(s) 1432A-R of the ND control plane 1424 typically include a reachability and forwarding information module to implement one or more routing protocols (e.g., an exterior gateway protocol such as Border Gateway Protocol (BGP), Interior Gateway Protocol(s) (IGP) (e.g., Open Shortest Path First (OSPF), Intermediate System to Intermediate System (IS-IS), Routing Information Protocol (RIP), Label Distribution Protocol (LDP), Resource Reservation Protocol (RSVP) (including RSVP-Traffic Engineering (TE): Extensions to RSVP for LSP Tunnels and Generalized Multi-Protocol Label Switching (GMPLS) Signaling RSVP-TE)) that communicate with other NEs to exchange routes, and then selects those routes based on one or more routing metrics. Thus, the NEs 1470A-H (e.g., the compute resource(s) 1412 executing the control communication and configuration module(s) 1432A-R) perform their responsibility for participating in controlling how data (e.g., packets) is to be routed (e.g., the next hop for the data and the outgoing physical NI for that data) by distributively determining the reachability within the network and calculating their respective forwarding information. Routes and adjacencies are stored in one or more routing structures (e.g., Routing Information Base (RIB), Label Information Base (LIB), one or more adjacency structures) on the ND control plane 1424. The ND control plane 1424 programs the ND forwarding plane 1426 with information (e.g., adjacency and route information) based on the routing structure(s). For example, the ND control plane 1424 programs the adjacency and route information into one or more forwarding table(s) 1434A-R (e.g., Forwarding Information Base (FIB), Label Forwarding Information Base (LFIB), and one or more adjacency structures) on the ND forwarding plane 1426. For layer 2 forwarding, the ND can store one or more bridging tables that are used to forward data based on the layer 2 information in that data. While the above example uses the special-purpose network device 1402, the same distributed approach 1472 can be implemented on the general-purpose network device 1404 and the hybrid network device 1406.
For example, where the special-purpose network device 1402 is used in the user plane 1480, each of the control communication and configuration module(s) 1432A-R of the ND control plane 1424 typically include a control agent that provides the VNE side of the south bound interface 1482. In this case, the ND control plane 1424 (the compute resource(s) 1412 executing the control communication and configuration module(s) 1432A-R) performs its responsibility for participating in controlling how data (e.g., packets) is to be routed (e.g., the next hop for the data and the outgoing physical NI for that data) through the control agent communicating with the centralized control plane 1476 to receive the forwarding information (and in some cases, the reachability information) from the centralized reachability and forwarding information module 1479 (it should be understood that in some embodiments of the invention, the control communication and configuration module(s) 1432A-R, in addition to communicating with the centralized control plane 1476, may also play some role in determining reachability and/or calculating forwarding information—albeit less so than in the case of a distributed approach; such embodiments are generally considered to fall under the centralized approach 1474, but may also be considered a hybrid approach). The control communication and configuration module 932A-R may implement a handover manager 1433A-R that may encompass the components of a distributed user plane function, tunnel routers and similar components and processes as described herein, in particular to the processes describe with reference to
While the above example uses the special-purpose network device 1402, the same centralized approach 1474 can be implemented with the general purpose network device 1404 (e.g., each of the VNE 1460A-R performs its responsibility for controlling how data (e.g., packets) is to be routed (e.g., the next hop for the data and the outgoing physical NI for that data) by communicating with the centralized control plane 1476 to receive the forwarding information (and in some cases, the reachability information) from the centralized reachability and forwarding information module 1479; it should be understood that in some embodiments of the invention, the VNEs 1460A-R, in addition to communicating with the centralized control plane 1476, may also play some role in determining reachability and/or calculating forwarding information—albeit less so than in the case of a distributed approach) and the hybrid network device 1406. In fact, the use of SDN techniques can enhance the NFV techniques typically used in the general-purpose network device 1404 or hybrid network device 1406 implementations as NFV is able to support SDN by providing an infrastructure upon which the SDN software can be run, and NFV and SDN both aim to make use of commodity server hardware and physical switches.
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While some embodiments of the invention implement the centralized control plane 1476 as a single entity (e.g., a single instance of software running on a single electronic device), alternative embodiments may spread the functionality across multiple entities for redundancy and/or scalability purposes (e.g., multiple instances of software running on different electronic devices).
Similar to the network device implementations, the electronic device(s) running the centralized control plane 1476, and thus the network controller 1478 including the centralized reachability and forwarding information module 1479, may be implemented a variety of ways (e.g., a special purpose device, a general-purpose (e.g., COTS) device, or hybrid device). These electronic device(s) would similarly include compute resource(s), a set or one or more physical NICs, and a non-transitory machine-readable storage medium having stored thereon the centralized control plane software. For instance,
In embodiments that use compute virtualization, the processor(s) 1542 typically execute software to instantiate a virtualization layer 1554 (e.g., in one embodiment the virtualization layer 1554 represents the kernel of an operating system (or a shim executing on a base operating system) that allows for the creation of multiple instances 1562A-R called software containers (representing separate user spaces and also called virtualization engines, virtual private servers, or jails) that may each be used to execute a set of one or more applications; in another embodiment the virtualization layer 1554 represents a hypervisor (sometimes referred to as a virtual machine monitor (VMM)) or a hypervisor executing on top of a host operating system, and an application is run on top of a guest operating system within an instance 1562A-R called a virtual machine (which in some cases may be considered a tightly isolated form of software container) that is run by the hypervisor; in another embodiment, an application is implemented as a unikernel, which can be generated by compiling directly with an application only a limited set of libraries (e.g., from a library operating system (LibOS) including drivers/libraries of OS services) that provide the particular OS services needed by the application, and the unikernel can run directly on hardware 1540, directly on a hypervisor represented by virtualization layer 1554 (in which case the unikernel is sometimes described as running within a LibOS virtual machine), or in a software container represented by one of instances 1562A-R). Again, in embodiments where compute virtualization is used, during operation an instance of the CCP software 1550 (illustrated as CCP instance 1576A) is executed (e.g., within the instance 1562A) on the virtualization layer 1554. In embodiments where compute virtualization is not used, the CCP instance 1576A is executed, as a unikernel or on top of a host operating system, on the “bare metal” general purpose control plane device 1504. The instantiation of the CCP instance 1576A, as well as the virtualization layer 1554 and instances 1562A-R if implemented, are collectively referred to as software instance(s) 1552.
In some embodiments, the CCP instance 1576A includes a network controller instance 1578. The network controller instance 1578 includes a centralized reachability and forwarding information module instance 1579 (which is a middleware layer providing the context of the network controller 1478 to the operating system and communicating with the various NEs), and an CCP application layer 1580 (sometimes referred to as an application layer) over the middleware layer (providing the intelligence required for various network operations such as protocols, network situational awareness, and user-interfaces). At a more abstract level, this CCP application layer 1580 within the centralized control plane 1476 works with virtual network view(s) (logical view(s) of the network) and the middleware layer provides the conversion from the virtual networks to the physical view. The CCP application layer 1580 may implement a handover manager 1481 that may encompass the components of a distributed user plane function (UPF), tunnel routers and similar components and processes as described herein, in particular to the processes describe with reference to
The centralized control plane 1476 transmits relevant messages to the user plane 1480 based on CCP application layer 1580 calculations and middleware layer mapping for each flow. A flow may be defined as a set of packets whose headers match a given pattern of bits; in this sense, traditional IP forwarding is also flow-based forwarding where the flows are defined by the destination IP address for example; however, in other implementations, the given pattern of bits used for a flow definition may include more fields (e.g., 10 or more) in the packet headers. Different NDs/NEs/VNEs of the user plane 1480 may receive different messages, and thus different forwarding information. The user plane 1480 processes these messages and programs the appropriate flow information and corresponding actions in the forwarding tables (sometime referred to as flow tables) of the appropriate NE/VNEs, and then the NEs/VNEs map incoming packets to flows represented in the forwarding tables and forward packets based on the matches in the forwarding tables.
Standards such as OpenFlow define the protocols used for the messages, as well as a model for processing the packets. The model for processing packets includes header parsing, packet classification, and making forwarding decisions. Header parsing describes how to interpret a packet based upon a well-known set of protocols. Some protocol fields are used to build a match structure (or key) that will be used in packet classification (e.g., a first key field could be a source media access control (MAC) address, and a second key field could be a destination MAC address).
Packet classification involves executing a lookup in memory to classify the packet by determining which entry (also referred to as a forwarding table entry or flow entry) in the forwarding tables best matches the packet based upon the match structure, or key, of the forwarding table entries. It is possible that many flows represented in the forwarding table entries can correspond/match to a packet; in this case the system is typically configured to determine one forwarding table entry from the many according to a defined scheme (e.g., selecting a first forwarding table entry that is matched). Forwarding table entries include both a specific set of match criteria (a set of values or wildcards, or an indication of what portions of a packet should be compared to a particular value/values/wildcards, as defined by the matching capabilities—for specific fields in the packet header, or for some other packet content), and a set of one or more actions for the user plane to take on receiving a matching packet. For example, an action may be to push a header onto the packet, for the packet using a particular port, flood the packet, or simply drop the packet. Thus, a forwarding table entry for IPv4/IPv6 packets with a particular transmission control protocol (TCP) destination port could contain an action specifying that these packets should be dropped.
Making forwarding decisions and performing actions occurs, based upon the forwarding table entry identified during packet classification, by executing the set of actions identified in the matched forwarding table entry on the packet.
However, when an unknown packet (for example, a “missed packet” or a “match-miss” as used in OpenFlow parlance) arrives at the user plane 1480, the packet (or a subset of the packet header and content) is typically forwarded to the centralized control plane 1476. The centralized control plane 1476 will then program forwarding table entries into the user plane 1480 to accommodate packets belonging to the flow of the unknown packet. Once a specific forwarding table entry has been programmed into the user plane 1480 by the centralized control plane 1476, the next packet with matching credentials will match that forwarding table entry and take the set of actions associated with that matched entry.
A network interface (NI) may be physical or virtual; and in the context of IP, an interface address is an IP address assigned to a NI, be it a physical NI or virtual NI. A virtual NI may be associated with a physical NI, with another virtual interface, or stand on its own (e.g., a loopback interface, a point-to-point protocol interface). A NI (physical or virtual) may be numbered (a NI with an IP address) or unnumbered (a NI without an IP address). A loopback interface (and its loopback address) is a specific type of virtual NI (and IP address) of a NE/VNE (physical or virtual) often used for management purposes; where such an IP address is referred to as the nodal loopback address. The IP address(es) assigned to the NI(s) of a ND are referred to as IP addresses of that ND; at a more granular level, the IP address(es) assigned to NI(s) assigned to a NE/VNE implemented on a ND can be referred to as IP addresses of that NE/VNE.
While the invention has been described in terms of several embodiments, those skilled in the art will recognize that the invention is not limited to the embodiments described, can be practiced with modification and alteration within the spirit and scope of the appended claims. The description is thus to be regarded as illustrative instead of limiting.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/IB2018/058409 | 10/26/2018 | WO | 00 |
