The architectural design of carrier-grade SDN
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doc fix document Apr 17, 2018 Updating for new msf ctrl functions Apr 16, 2018

Multi-Service Fabric (MSF)

MSF is the architectural design of carrier-grade SDN that provides wide logical network slices with general purpose switches. We are studying architectural designs with the aim of solving the following problems we are having.

  • Immutable low-cost architecture
    • Capable to employ any product that is most economical and suitable at each moment, for providing functions required for service provider network.
  • Unlimited and adaptive Scalability
    • Capable to provide any level of scale needed for any use case.
  • Applicability of Any-vendor product
    • Simplified functions and unified specification in order to enable to select Any-vendor's products as you like.
  • Easy Maintenance
    • Capable to make use of small, simple and transparent equipment in order to let it easy to detect and fix the cause in case of failure.

Design Policy

  • Applicable to both data center and service provider network with the same architecture
  • Use commodity hardware and open source software, open interface as much as possible
  • Support carrier-grade scalability and stability by making use the autonomous and distributed IP function of the switches
  • Provide service common functions on the switches and service dependent functions on servers in cloud
  • In order for quick commercial deployment, it must be interoperable with existing networks using legacy protocols
  • Solving limitation of commodity switches is assisted by the controller that organizes the switch cluster as a fabric


  • Centralized management: Network management and abstraction are performed by the controller, such as managing IP-VPN, switch set-up, or switch clustering (switch cluster with clos-topology is treated as one logical switch).
  • Distributed/Autonomous: Network routing is done among the switches.



Controller is in charge of managing both overlay and underlay network. In overlay, the controller adds/removes the L2/L3 slice (VPN) or creates/deletes CP (Connection Point with cluster network). In underlay, automatic configuration for switches (with Zero Touch Provisioning (ZTP)), and connection to the network are supported. Controller also has some functions to improve operability, reliability.

Controller consists of three major components.

  • Fabric Controller (FC) is managing switch fabric model and network model.
  • Element Controller (EC) converts logical and physical information.
  • Element Manager (EM) provides switch driver to absorb difference of vendor-specific.


Furthermore, in order to connect between multiple data centers, Multi-Fabric Controller (MFC) aggregates the controllers (FC/EC/EM) of each location.


Fabric Controller (FC)


Element Controller (EC)


Element Manager (EM)



Concept_Functionality_and_NetworkScale (PDF) describes concept and overview, for your understanding of our project.

Technical_Details (PDF) describes more technical information about typical functions and basic operations for using controllers.


If you have any questions, enhancement requests, let us know with issue, or please contact msf-contact [at]


This project is a part of Multi-Service Fabric.