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Vorlage:Kurzbeschreibung SD-WAN ist ein Akronym für software-defined networking – deutsch: softwaredefinierte Vernetzung – in einem Wide Area Network (WAN). SD-WAN vereinfacht die Verwaltung und den Betrieb eines WANs, indem es die Hardware des Netzwerks von ihrem Steuermechanismus entkoppelt (trennt). Dieses Konzept ähnelt der Art und Weise, wie softwaredefinierte Netzwerke Virtualisierungstechnologie implementieren, um das Management und den Betrieb von Rechenzentren zu verbessern.[1]

Eine zentrale Anwendung von SD-WAN ist es, über einen kostengünstigeren und kommerziell verfügbaren Internetzugang den Aufbau leistungsfähigerer WANs zu ermöglichen, um so teurere private WAN-Verbindungstechnologien wie Multiprotocol Label Switching (MPLS) ganz oder teilweise zu ersetzen.[1]

Das amerikanische Marktforschungsunternehmen Gartner prognostizierte 2015, dass bis Ende 2019 30% der Unternehmen die SD-WAN-Technologie in ihren Niederlassungen einsetzen werden.[2]

Overview

WANs allow companies to extend their computer networks over large distances, to connect remote branch offices to data centers and each other, and deliver the applications and services required to perform business functions. When companies extend networks over greater distances and sometimes across multiple carriers' networks, they face operational challenges including network congestion, packet delay variation,[3] packet loss,[4] and even service outages. Modern applications such as VoIP calling, videoconferencing, streaming media, and virtualized applications and desktops require low latency.[5] Bandwidth requirements are also increasing, especially for applications featuring high-definition video.[6] It can be expensive and difficult to expand WAN capability, with corresponding difficulties related to network management and troubleshooting.[1]

SD-WAN products are designed to address these network problems.[7] By enhancing or even replacing traditional branch routers with virtualization appliances that can control application-level policies and offer a network overlay, less expensive consumer-grade Internet links can act more like a dedicated circuit. This simplifies the setup process for branch personnel.[8] SD-WAN products can be physical appliances or virtual appliances, and are placed in small remote and branch offices, larger offices, corporate data centers, and increasingly on cloud platforms.[7]

A centralized controller is used to set policies and prioritize traffic. The SD-WAN takes into account these policies and the availability of network bandwidth to route traffic. This helps ensure that application performance meets service level agreements (SLAs).[9]

History

SD-WAN consists of several technologies combined with newer enhancements. Redundant telecommunication links connecting remote sites date back to the 1970s with X.25 links used for remote mainframe terminal access.[10] Central management of those links with a greater focus on application delivery across the WAN started to become popular in the mid-2000s.[11] SD-WAN combines the two, and adds the ability to dynamically share network bandwidth across the connection points.[1] Additional enhancements include central controllers, zero-touch provisioning, integrated analytics and on-demand circuit provisioning, with some network intelligence based in the cloud, allowing centralized policy management and security.[12]

Networking publications started using the term SD-WAN to describe this new networking trend as early as 2014.[7]

Required characteristics

Research firm Gartner has defined an SD-WAN as having four required characteristics:[1]

  • The ability to support multiple connection types, such as MPLS, frame relay and higher capacity LTE wireless communications
  • The ability to do dynamic path selection, for load sharing and resiliency purposes
  • A simple interface that is easy to configure and manage
  • The ability to support VPNs, and third party services such as WAN optimization controllers, firewalls and web gateways

Form factors

SD-WAN products can be physical appliances or software based.[13]

Features

Features of SD-WANs include resilience, security, performance, and quality of service (QoS), with flexible deployment options and simplified administration and troubleshooting.

Resilience

A resilient SD-WAN reduces network downtime. The technology must feature real time detection of outages and automatic switch over to working links.[14]

Quality of service

SD-WAN technology supports quality of service by having application level awareness, giving bandwidth priority to the most critical applications. This may include dynamic path selection, sending an application on a faster link, or even splitting an application between two paths to improve performance by delivering it faster.[14]

Security

SD-WAN communication is usually secured using IPsec, a staple of WAN security.[15]

Application optimization

SD-WANs can improve application delivery using caching, storing recently accessed information in memory to speed future access.[16]

Deployment options

Most SD-WAN products are available as pre-configured appliances, placed at the network edge in data centers, branch offices and other remote locations. There are also virtual appliances that can work on existing network hardware, or the appliance can be deployed as a virtual appliance on the cloud in environments such as Amazon Web Services (AWS), Unified Communications as a service (UCaaS) or as Software as a Service (SaaS).[17] This allows enterprises to benefit from SD-WAN services as they migrate application delivery from corporate servers to cloud based services such as Salesforce.com and Google apps.[13]

Administration and troubleshooting

Management simplicity is a key requirement for SD-WANs, per Gartner. As with network equipment in general, GUIs may be preferred to command line interface (CLI) methods of configuration and control.[18] Other beneficial administrative features include automatic path selection, the ability to centrally configure each end appliance by pushing configuration changes out, and even a true software defined networking approach that lets all appliances and virtual appliances be configured centrally based on application needs rather than underlying hardware.[1]

Online traffic engineering

With a global view of network status, a controller that manages SD-WAN can perform careful and adaptive traffic engineering by assigning new transfer requests according to current usage of resources (links). For example, this can be achieved by performing central calculation of transmission rates at the controller and rate-limiting at the senders (end-points) according to such rates.[19][20][21][22][23]

Complementary technology

SD-WAN versus WAN Optimization

There are some similarities between SD-WAN and WAN optimization, the name given to the collection of techniques used to increase data-transfer efficiencies across WANs. The goal of each is to accelerate application delivery between branch offices and data centers, but SD-WAN technology focuses additionally on cost savings and efficiency, specifically by allowing lower cost network links to perform the work of more expensive leased lines, whereas WAN Optimization focuses squarely on improving packet delivery. An SD-WAN utilizing virtualization techniques assisted with WAN Optimization traffic control allows network bandwidth to dynamically grow or shrink as needed. SD-WAN technology and WAN optimization can be used separately or together,[24] and some SD-WAN vendors are adding WAN optimization features to their products.[16][25]

WAN edge routers

A WAN edge router is a device that routes data packets between different WAN locations, giving an enterprise access to a carrier network. Also called a boundary router, it is unlike a core router, which only sends packets within a single network.[26] SD-WANs can work as an overlay to simplify the management of existing WAN edge routers, by lowering dependence on routing protocols.[7] SD-WAN can also potentially be an alternative to WAN Edge routers.[8]

SD-WAN versus hybrid WAN

SD-WANs are similar to hybrid WANs, and sometimes the terms are used interchangeably, but they are not identical. A hybrid WAN consists of different connection types, and may have a software defined network (SDN) component, but doesn't have to.[27]

SD-WAN versus MPLS

Cloud-based SD-WAN offers advanced features, such as enhanced security, seamless cloud and support for mobile users, that result naturally from the use of cloud infrastructure. As a result, cloud-based SD-WAN can replace MPLS, enabling organizations to release resources once tied to WAN investments and create new capabilities.[28]

Testing & validation

As there is no standard algorithm for SD-WAN controllers, device manufacturers each use their own proprietary algorithm in the transmission of data. These algorithms determine which traffic to direct over which link and when to switch traffic from one link to another. Given the breadth of options available in relation to both software and hardware SD-WAN control solutions, it's imperative they be tested and validated under real-world conditions within a lab setting prior to deployment.Vorlage:Citation needed

There are multiple solutions available for testing purposes, ranging from purpose-built network emulation appliances which can apply specified network impairments to the network being tested in order to reliably validate performance, to software-based solutions.Vorlage:Citation needed

Marketplace

IT website Network World divides the SD-WAN vendor market into three groups: established networking vendors who are adding SD-WAN products to their offerings, WAN specialists who are starting to integrate SD-WAN functionality into their products, and startups focused specifically on the SD-WAN market.[1]

Alternatively, a market overview by Nemertes Research groups SD-WAN vendors into categories based on their original technology space, and which are "Pure-play SD-WAN providers", "WAN optimization vendors", "Link-aggregation vendors", and "General network vendors"[29] While Network World's second category (startups focused specifically on the SD-WAN market), is generally equivalent to Nemertes' "Pure-play SD-WAN providers" category, Nemertes offers a more detailed view of the preexisting WAN and overall networking providers.

Additionally, Nemertes Research also describes the in-net side of the SD-WAN market, describing the go-to-market strategy of connectivity providers entering the SD-WAN market. These providers include "Network-as-a-service vendors", "Carriers or telcos", "Content delivery networks" and "Secure WAN providers".[29]

Several online resources, including the networking technology podcast "Packet Pushers", keep an updated list of existing SD-WAN vendors.[16] In June 2018, Network World named 10 hot SD-WAN startups.[30]

References

Vorlage:Reflist

[[Category:Computing terminology]] [[Category:Configuration management]] [[Category:Data transmission]] [[Category:Emerging technologies]] [[Category:Network architecture]] [[Category:Telecommunications]] [[Category:Wide area networks]]

  1. ↑ a b c d e f g SD-WAN: What it is and why you’ll use it one day. networkworld.com. 10. Februar 2016. Abgerufen am 27. Juni 2016.
  2. ↑ Predicting SD-WAN Adoption. gartner.com. 15. Dezember 2015. Abgerufen am 27. Juni 2016.
  3. ↑ How to address WAN jitter issues for real-time applications. networkworld.com. 22. Oktober 2012. Abgerufen am 27. Juni 2016.
  4. ↑ What’s slowing down your network and how to fix it. computerweekly.com. 1. April 2015. Abgerufen am 27. Juni 2016.
  5. ↑ Low-latency networks aren’t just for Wall Street anymore. gigaom.com. 6. April 2012. Abgerufen am 27. Juni 2016.
  6. ↑ How fast should my Internet connection be to watch streaming HD movies?. HowStuffWorks.com. 31. Oktober 2011. Abgerufen am 27. Juni 2016.
  7. ↑ a b c d Software-Defined WAN: A Primer. networkcomputing.com. 9. September 2014. Abgerufen am 27. Juni 2016.
  8. ↑ a b SD-What? Understanding SD-WAN. techtarget.com. Abgerufen am 28. Juni 2016.
  9. ↑ SD-WAN Vendors Making A Splash. networkcomputing.com. 27. August 2015. Abgerufen am 28. Juni 2016.
  10. ↑ A Brief History of the Enterprise WAN. networkworld.com. 6. April 2012. Abgerufen am 28. Juni 2016.
  11. ↑ Managing the WAN. networkworld.com. 13. März 2006. Abgerufen am 28. Juni 2016.
  12. ↑ SD-WAN: The Killer App For Enterprise SDN?. networkcomputing.com. 22. Juli 2015. Abgerufen am 28. Juni 2016.
  13. ↑ a b SD-WAN: Bringing WAN Sexy Back. nojitter.com. 2. November 2015. Abgerufen am 29. Juni 2016.
  14. ↑ a b Do wide area networks need to get software-defined?. techtarget.com. Abgerufen am 13. Mai 2015.
  15. ↑ How IPsec provides secure communications. techtarget.com. Abgerufen am 29. Juni 2016.
  16. ↑ a b c List of SD-WAN Vendors. packetpushers.net. Abgerufen am 29. Juni 2016.
  17. ↑ Linda Hardesty: Oracle’s Purchase of Talari Makes It the First Major Public Cloud Provider to Offer SD-WAN, SDX Central. 20 December 2018. Abgerufen im 27 January 2019. 
  18. ↑ Difference Between GUI and Command Line. differencebtw.com. 29. Mai 2015. Abgerufen am 29. Juni 2016.
  19. ↑ C. Hong: Achieving High Utilization with Software-Driven WAN. ACM SIGCOMM. 2013.
  20. ↑ S. Kandula: Calendaring for Wide Area Networks. ACM SIGCOMM. 2014.
  21. ↑ H. Zhang: Guaranteeing Deadlines for Inter-Datacenter Transfers. ACM EUROSYS. 2015.
  22. ↑ M. Noormohammadpour: DCCast: Efficient Point to Multipoint Transfers Across Datacenters. USENIX HOTCLOUD. 2017.
  23. ↑ M. Noormohammadpour: QuickCast: Fast and Efficient Inter-Datacenter Transfers using Forwarding Tree Cohorts. IEEE INFOCOM. 2018. Abgerufen im January 23, 2018.
  24. ↑ Why SD-WAN is the next breed of WAN optimization. techtarget.com. Abgerufen am 29. Juni 2016.
  25. ↑ Citrix Combines SD-WAN, WAN Optimization In Single Appliance. packetpushers.com. 16. März 2016. Abgerufen am 29. Juni 2016.
  26. ↑ Definition: edge router. techtarget.com. Abgerufen am 29. Juni 2016.
  27. ↑ Definition hybrid WAN. techtarget.com. Abgerufen am 22. August 2016.
  28. ↑ SD-WAN vs. MPLS vs. Public Internet. Abgerufen am 28. Februar 2018.
  29. ↑ a b SD-WAN providers: Consider the small with the big (en-US). In: SearchSDN. Abgerufen am 1. November 2017. 
  30. ↑ Jeff Vance: 10 hot SD-WAN startups to watch (en). In: Network World. Abgerufen am 30. Oktober 2018. 
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