This paper describes a novel Software-Defined Networking (SDN) Controller architecture that is built on Model-Driven Software Engineering (MDSE) principles. It supports both the “classic” OpenFlow-based approach to SDN and emerging model-driven network management/programmability technologies, such as NETCONF/YANG. The architecture was first implemented in the OpenDaylight Project Hydrogen release, and it is being further evolved in subsequent OpenDaylight releases.

OpenDaylight: Towards a Model-Driven SDN Controller architecture

Segment Routing (SR) leverages the source routing paradigm. A node
steers a packet through an ordered list of instructions, called
segments. A segment can represent any instruction, topological or
service-based. A segment can have a semantic local to an SR node or
global within an SR domain. SR allows to enforce a flow through any
topological path while maintaining per-flow state only at the ingress
nodes to the SR domain. Segment Routing can be directly applied to the
MPLS architecture with no change on the forwarding plane. A segment is
encoded as an MPLS label. An ordered list of segments is encoded as a
stack of labels. The segment to process is on the top of the stack.
Upon completion of a segment, the related label is popped from the
stack. Segment Routing can be applied to the IPv6 architecture, with a
new type of routing header. A segment is encoded as an IPv6 address.
An ordered list of segments is encoded as an ordered list of IPv6
addresses in the routing header. The active segment is indicated by
the Destination Address of the packet. The next active segment is
indicated by a pointer in the new routing header.

Segment Routing Architecture

In general, techniques are described for configuring and managing virtual networks. For example, a distributed virtual network controller is described that configures and manages an overlay network within a physical network formed by plurality of switches. A plurality of servers are interconnected by the switch fabric, each of the servers comprising an operating environment executing one or more virtual machines in communication via the overlay networks. The servers comprises a set of virtual switches that extends the overlay network as a virtual network to the operating environment of the virtual machines. The controller may instruct the servers and the virtual switches to perform various operations, such as determining a physical network path taken by packets of a network packet flow, determining latency through the network, re-routing traffic in the virtual network due to network events, replicating traffic for multicasting, providing multi-tenant services to support multiple virtual networks, monitoring and logging traffic characteristics within the virtual networks and other operations.

Physical path determination for virtual network packet flows

As the proliferation of data rich content and increasingly more capable mobile devices has continued, the amount of data communicated over mobile operator's networks has increased Upgrading the existing network that was designed for voice calls is not desirable or practical for many mobile operators This disclosure relates to a mobility edge gateway that resides on the edge of the core network and can provide one or more services such as call localization, offloading of traffic, session management, and content streaming The call localization involves identifying calls that can be maintained at the edge of the network and bridging the calls at the mobility edge gateway to bypass the core network The offloading involves identifying traffic and offloading the traffic to the Internet or another network to bypass the core network These services can relieve congestion on the core network of mobile operator's networks

Providing services at a communication network edge

Network operators anticipate the offering of an increasing variety of cloud-based services with stringent Service Level Agreements. Technologies currently supporting IP networks however lack the flexibility and scalability properties to realize such evolution. In this article, we present Segment Routing (SR), a new network architecture aimed at filling this gap, driven by use-cases defined by network operators. SR implements the source routing and tunneling paradigms, letting nodes steer packets over paths using a sequence of instructions (segments) placed in the packet header. As such, SR allows the implementation of routing policies without per-flow entries at intermediate routers. This paper introduces the SR architecture, describes its related ongoing standardization efforts, and reviews the main use-cases envisioned by network operators.

The Segment Routing Architecture

A centralized controller provides dynamic end-to-end network path setup across multiple network layers. In particular, the centralized controller manages end-to-end network path setup that provisions a path at both the transport network layer (e.g., optical) and the service network layer (e.g., IP/MPLS). The centralized controller performs path computation for an optical path at the transport network layer and for a path at the service network layer that transports network traffic on the underlying optical transport path, based on information obtained by the centralized controller from the underlying network components at both layers.

Dynamic end-to-end network path setup across multiple network layers

An extensible software defined network (SDN) controller is described that provides an application-aware framework that enable a variety of different user applications to communicate with the controller and that allows the controller to automatically configure devices in a network based on the needs of the applications. For example, the controller includes a plurality of different northbound interfaces that enable a variety of different user applications to communicate with the controller. The controller also includes multiple southbound protocols for configuring and enabling functionality in network devices based on the communications with the user applications.

Software defined network controller

A method performed by a network device may include assembling a multiprotocol label switching (MPLS) echo request, the echo request including an instruction for a transit node to forward the echo request via a bypass path associated with the transit node, and an instruction for an egress node to send an echo reply indicating that the echo request was received on the bypass path. The method may also include sending the MPLS echo request over a functioning label switched path (LSP).

LSP ping and traceroute for bypass tunnels

In general, principles of the invention relate to techniques for detecting data plane failures in Multi-Protocol Label Switching (MPLS) Label-Switched Paths (LSPs) that may be tunneled over one or more other LSPs. More specifically, the techniques described herein allow for testing connectivity of an LSP that is tunneled through at least one other LSP, and testing connectivity of an inter-autonomous system LSP. For example, a method comprises providing, with an intermediate label-switching router (LSR) of an LSP, instructions to an ingress LSR of the LSP to modify a forwarding equivalence class (FEC) stack of MPLS echo request packets. The intermediate LSR may provide the instructions within an MPLS echo reply packet.

Failure detection for tunneled label-switched paths

An ingress router of a provider network receives a packet from a customer network, determines that the packet includes a customer network label and that the packet is to be tunneled through the provider network, based on the determination, adds a delimiter label to the packet indicative of a bottom of a provider network label stack and one or more provider network labels to the packet, and forwards the packet to a next routing device along the provider network tunnel. An egress routing device of the provider network receives a packet comprising a provider network label stack, removes the provider network label stack from the packet, determines whether the packet comprises a delimiter label following the provider network label stack, and, when the packet comprises the delimiter label, forwards the packet to a customer network interface device.

Network tunneling using a label stack delimiter

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