Computer News No. 123  Sep.-Oct. 2006  

Optical HARNET Provides 10G Connectivity Between HK Universities

    1. Background
    2. Recent progress
    3. Highlights of the optical HARNET network infrastructure
    4. Two central exchange points at HKU and CUHK connecting to the Internet

1. Background

In issue no. 122 of Computer News, we reported on the Computer Centre working with the JUCC (Joint Universities Computer Centre) to implement the new optical network backbone of HARNET (The Hong Kong Academic and Research NETwork) to cope with increasing demands for Internet bandwidth to facilitate the research and academic activities of the 8 tertiary education institutions.  The optical backbone provides two 10Gbps rings covering all the 8 institutions on HARNET.  It employs Dense Wavelength Division Multiplexing (DWDM) optical technology to optimize the data carrying capacity of a single optical fiber.  It  can also facilitate academic research activities because different network services (e.g. data traffic, high-definition video stream, SAN storage connection, etc) can be carried on different wavelengths (lambda) over a single fiber connection.

We are pleased to report on the progress of the project.

2. Recent progress

After the tendering exercise by JUCC, the vendor PCCW was selected to provide the required fiber connections and optical networking equipment for HARNET institutions.  Since July 2006, the Computer Centre has been working closely with the JUCC on the upgrade and on extensive network backbone reconfiguration works. The optical equipment was installed by the vendor and testing work had been completed in September, 2006. Afterwards, Internet2 traffic of HARNET institutions was migrated to travel through the new optical HARNET backbone since early October, 2006.  The JUCC Network Task Force (NTF) is closely monitoring on the new optical network with the vendor, and further tuning of network parameters would be carried out when required.

Besides normal data traffic, JUCC NTF is also arranging testing with the vendor on remote SAN storage backup and on high-quality video transmission . We will report on further progress in the future Computer News.

3. Highlights of the optical HARNET network infrastructure

The 8 institutions on the optical HARNET are connected to form a "ring in ring" network design. (See Figure 1.)  There is a large "outer ring" connecting all 8 institutions and a smaller "inner ring" connecting HKU, CUHK, HKUST,and PolyU.  Each 10Gbps ring has fail-over protection, resulting in 5Gbps usable bandwidth per ring.  Self healing switching time is less than 50ms, and thus providing fast self-healing resilience for the optical HARNET.

In the new optical HARNET set-up, Nortel OME6500 optical switch equipped with optical multiplexers are installed at all 8 HARNET institutions.  The new optical backbone provides Gigabit Ethernet (GE) connections and Fiber Channel (FC) connections.  The FC connections enable collaboration between HARNET institutions for remote backup based on SAN connections.  The new optical HARNET backbone provides the flexibility to reconfigure the GE and FC connections between the institutions as the need arises.
Figure 1: Optical HARNET network topology (September 2006)

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4. Two central exchange points at HKU and CUHK connecting to the Internet

Two central exchange points are established at HKU and CUHK to which the GE wide area network connections from the other six institutions are connected.  The two central exchange points provide redundant connections to the network of the vendor PCCW for connecting to the Internet. 

The existing HARNET is still running till next summer when it will be wholly superseded by the new optical HARNET.  The new optical HARNET network configuration is more complicated than before.  As the Computer Centre takes up the role of running a central exchange point, the workload on network support and network management is increased.  We shall strive to keep the state-of-the-art optical HARNET serve the University and HARNET better.