Software-Defined Network

The CityU Data Centre Network has been upgraded to leverage the latest Software-Defined Network (SDN) technology. This two-tier spine-leaf architecture builds on high-throughput and low latency network equipment.

SDN

Spine-and-Leaf Architecture

A lower-tier switch (leaf layer) connects to the top-tier switches (spine layer) in a full-mesh topology in this two-tier architecture. The leaf layer consists of switches that connect to servers in the Data Centres.

With a spine-leaf architecture, data from one server always cross the same number of network equipment to get to another server, keeping latency at the lowest level because data only have to hop to a spine and a leaf switch to reach its destination.

Benefits of Spine-and-Leaf

  1. High performance and low latency
    The spine-leaf data centre network architecture can improve performance when handling the predominantly server-to-server communication (i.e. east-west traffic) within the data centres, shortening the communication path between servers to significantly increase application and service performance.
  2. Higher Bandwidth and Availability
    Spine-leaf architectures rely on Equal-Cost Multipath (ECMP) protocols to load balancing traffic across multiple available paths. ECMP can significantly increase the server-to-server communication bandwidth, and resilience/availability in case of path failures; traffic will flow via other available paths after failure detection.
  3. Scalability and Flexibility
    Spine-leaf is a highly scalable architecture. Additional spine switches can be added at any time to increase the Data Centre network capacity. In addition, new leaf switches can also be seamlessly installed to “scale out” the network infrastructure without any network interruption.
  4. Segmentation and Security
    SDN also leverages Virtual Extensible Network (VxLAN) technology to virtualise the physical network, provides a much higher security access control by segmenting the data centre network into distinct security segments. This segmentation can also help to facilitate infrastructure sharing among different institutional and academic needs.

IT.ServiceDesk@cityu.edu.hk