SDN (Software-Defined Networking)を活用し，すぐに災害復旧できるバックボーンネットワーク
グエン キエン, トラン ミン クウアン, 山田茂樹

どんな研究？

何が分かる？

The current technology of Internet provides an acceptablelevel of resilience in normal operation. However, the Internet
may get catastrophic impacts when unexpected disasters
such as earthquake, tsunami happen. Especially, the Internet
backbones face many challenges to normal operation including
power outage, link, node failures, rerouting packets, trafficengineering etc. Therefore, it is necessary to research newtechnologies for fast recovery backbone networks.

SDN (Software-Defined Networking）は、ネットワークの転送機能と制御機能を分離 して構成する技術で、OpenFlowと言うプロトコルを使ってネットワークを、プログラ ムのように人間の意図通りに簡単に動作させることを狙った技術です。この研究は、SDN技術を活用して災害からすぐに立ち直ることのできるバックボーンネットワークを構築することを目指しています。SDNで災害で破壊されたバックボーンネットワークを復旧させる手法の長所と短所を検討した上で我々の解決策を提示するとともに、その評価結果も御紹介します。

SDN approach for disaster-resilient backbones
Goal : Keeping unstoppable Internet services during disasters

Software-Defined Networking (SDN) architecture
decouples the network control and forwarding
functions enabling the network control to become
directly programmable and the underlying
infrastructure to be abstracted for applications andnetwork services. The OpenFlow™ protocol is afoundational element for building SDN solutions.

Our current approach

Challenges① SDN at network
backbone level?
② Fast failure detection
and restoration③ Efficient trafficengineering④ Efficient cooperation
with the service provision
layer (later phase)

Limitations of the current technologies•••

Routing protocol (BGP, OSPF) long convergence time
Extremely hard to debug and manage
Not well cooperated with service provider (i.e., cloudcomputing)
Network Operating system (NOS) has a global view of the network f(Map)

Performance evaluation examples
Example 1: We investigate the latencies between controllers and switches in order to find the appropriate number andlocations of controllers
CDFs of average latency

CDFs of worst-case latency

Pareto optimal

Method: Assuming all SDN/OpenFlow devices are deployed on SINET3, the number of controller is varied from one to four. All
possible locations of controllers are investigated, and the optimal values are revealed. The details of latency metrics are in *.
SINET3 is the Japanese Research and Education
Network, operated by NII. The topology fromhttp://www.topology-zoo.org/

In term of latency, one controller is enough for the SINET3* Kien Nguyen, Quang Tran Minh, and Shigeki Yamada. “A Software-Defined Networking approach for Disaster-Resilient WANs” , Proc. Of PMECT 2013 (accepted)).

Example 2: We investigate reactive switch-over from a faulty link to an alternative link on a part of SINET3, assuming arealistic scenario
Receive Rate on Tokyo Host (Iperf client)

Goodput on the alternative path

Method: We simulated the following disasterrecovery scenario in SINET3. First, a TCP flow
is generated over a path between Iperf serverand client. Then an earthquake occurs, andthe path is broken due to link failure. Acontroller finally sets up an alternative pathfor the TCP flow, using OpenFlow protocol.
Fast restoration of TCP traffic using SDN/OpenFlow technology

NII

連絡先：グエン キエン, トラン ミン クウアン, 山田茂樹／ 国立情報学研究所 情報学プリンシプル研究系 教授
TEL : 03-4212-2654

URL: http://klab.nii.ac.jp/~kien/

Email : {kienng, quangtran, shigeki}@nii.ac.jp