Software Defined Networking (SDN)
Software Defined Networking (SDN) has as its broad aim to open up the control of flows through the network to user-customizable software which is independent of the hardware which forwards the flows. Once the control software is separated from the hardware and morphed to a more open environment, users are able to reap many benefits, including the following:
- Network and service customizability.
- Improved operations.
- Increased performance.
Different Approaches to SDN
Originating from the academic community, SDN is a relatively new concept which has formed multiple approaches all of which serve the common SDN agenda but do so in distinct fashions. Two approaches have risen to prominence with differences in pedigree and implementation making each applicable to different markets but not so much that they cannot be deployed together – creating a hybrid SDN solution.
Born in university research labs, OpenFlow is defined in the recently formed Open Networking Foundation. OpenFlow removes the entire control plane from the network equipment relegating it to a data-plane only role. New mechanisms of network control (discovery, path computation, path setup etc...) are created and hosted on a server/cloud. Although applicable to telco/WAN, early work has focused on data center and campus applications.
Standardized in the IETF, PCE takes an evolutionary approach and migrates only the path computation component of traditional networking devices to a centralized role. Much of the well established and proven software functions of the control plane are left untouched and remain integrated within the NEs enabling a gradual migration to SDN. PCE has the added benefit of providing inter-domain networking which is a key application for carrier networks. These attributes make PCE the preferred approach to SDN for telco/WAN environments.
PCE-based SDN Preferred for the Telco/WAN
The OpenFlow model is more revolutionary in concept which comes at the cost of requiring a forklift upgrade. With OpenFlow all devices along the path of a flow must support OpenFlow before the path is available, no matter what equipment modification or replacement that may require. A wholesale change of this nature makes it particularly well suited for closed environments such as data centers and campus networks, where IP routing and MPLS signaling are not widely deployed. However, the complete upheaval of control plane function in the WAN, where IP routing and MPLS prevail, is not well suited for incumbent service providers with massive investments in network elements and legacy service requirements.
In contrast, SDN Migration with a PCE-based approach can be gradual and/or partial. With PCE, only the ingress node of a flow needs to be upgraded. Network elements that are not yet upgraded with PCE may still be used in paths and may also continue to function as ingress nodes using their existing path computation function. Moreover, the heavy investments carriers have made in IP routing and MPLS control plane technologies remain intact. For Telco/WAN environments, this approach is significantly less cost, less risk, and less disruptive than OpenFlow making it the preferred approach for SDN.
Metaswitch has extended its Integrated Control Plane solution, which is widely deployed in Telco/WAN networks, to fully support PCE.
Features and Benefits
Metaswitch’s PCE solution offers the following features and benefits.
- Control plane / virtualization expertise
- Developed by routing, signaling, and virtualization experts
- Pre-integrated with leading MPLS/GMPLS solution
- Flexibility / Modularity
- Portable to any OS, any architecture
- PCE client integrated into any NE
- PCE client/server integrated into an OSS
- PCE server can run on any PC or cloud environment
- Open APIs for customization
- Opens control of the control plane to the service providers
- Massive scalability
- Vital for PCE servers
- Arbitrary parallelization
- Multi-thread, multi-core, multi-CPU support
- Robust fault tolerance
- Part of Metaswitch High Availability Framework
- Full distribution support
The Metaswitch solution for manufacturers of packet-optical devices is based on the following elements.
- DC-PCE including PCE Client and Server support
- Metaswitch's Integrated Control Plane, which can be used to implement a MPLS/GMPLS and IP Routing control plane on a huge range of network equipment
- High Availability Framework (HAF), Metaswitch's architecture for delivering fault tolerance and reduced downtime across the range of network protocols
- N-BASE, Metaswitch's portable operating environment for network software products
- Metaswitch professional services, training, and support directly from the Metaswitch engineering organization