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Network Working Group                                            S. Hyun
Internet-Draft                                                  J. Jeong
Intended status: Standards Track                                  S. Woo
Expires: May 17, 2017                                             Y. Yeo
                                                 Sungkyunkwan University
                                                                 J. Park
                                                                    ETRI
                                                       November 13, 2016


           NSF-triggered Traffic Steering in I2NSF Framework
               draft-hyun-i2nsf-nsf-triggered-steering-01

Abstract

   This document describes an architecture of the framework for
   Interface to Network Security Functions (I2NSF) which enables traffic
   steering between Network Security Functions (NSFs) for security
   policy enforcement.  Such traffic steering enables composite
   inspection of network traffic by steering the traffic through
   multiple types of NSFs according to the information model for the
   NSF-facing interface in the I2NSF framework.  This document explains
   the additional components integrated into the I2NSF framework and
   their functionalities to achieve NSF-triggered traffic steering.  It
   also describes representative use cases to address major benefits
   from the proposed architecture.

Status of This Memo

   This Internet-Draft is submitted to IETF in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
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   This Internet-Draft will expire on May 17, 2017.

Copyright Notice

   Copyright (c) 2016 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
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   described in the Simplified BSD License.

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Objective  . . . . . . . . . . . . . . . . . . . . . . . . . .  3
   3.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  4
   4.  Architecture . . . . . . . . . . . . . . . . . . . . . . . . .  5
     4.1.  NSF Operation Manager  . . . . . . . . . . . . . . . . . .  7
     4.2.  Developer's Management System  . . . . . . . . . . . . . .  7
     4.3.  Packet Forwarding Header . . . . . . . . . . . . . . . . .  8
     4.4.  Network Security Function Forwarder (NSFF) . . . . . . . .  8
   5.  Use Cases  . . . . . . . . . . . . . . . . . . . . . . . . . .  9
     5.1.  Enforcing Different NSFs Depending on a Packet
           Source's Trust Level . . . . . . . . . . . . . . . . . . .  9
     5.2.  Effective Load Balancing with Dynamic NSF Instantiation  . 10
   6.  Security Considerations  . . . . . . . . . . . . . . . . . . . 11
   7.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 11
   8.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 11
     8.1.  Normative References . . . . . . . . . . . . . . . . . . . 11
     8.2.  Informative References . . . . . . . . . . . . . . . . . . 12















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1.  Introduction

   To effectively cope with emerging sophisticated network attacks, it
   is necessary that various Network Security Functions (NSFs)
   cooperatively analyze network traffic [sfc-ns-use-cases][RFC7498]
   [i2nsf-problem][capability-im].  In addition, depending on the
   characteristics of network traffic and their suspiciousness level,
   the different types of network traffic need to be analyzed through
   the different sets of NSFs.  An information model in [capability-im]
   is proposed for NSF-facing interface in the framework for Interface
   to Network Security Functions (I2NSF) that enables an NSF to trigger
   further inspection by calling another NSF based on its own analysis
   results [i2nsf-framework].  However, the current design of the I2NSF
   framework does not consider network traffic steering fully in order
   to enable such consecutive inspections through multiple NSFs.

   In this document, we propose an architecture that integrates
   additional components for traffic steering over NSFs into the I2NSF
   framework.  We extend the security controller's functionalities such
   that it can interpret a high-level policy of NSF-triggered traffic
   steering into a low-level policy and manage them.  It also keeps
   track of the available NSF instances and their information (e.g.,
   network information and workload), and makes a decision on which NSF
   instances to use for a given NSF.  Based on the forwarding
   information provided by the security controller, a Network Security
   Function Forwarder (NSFF) performs network traffic steering through
   required NSFs.  The NSFF is also responsible for interpreting
   inspection result from an NSF to enforce more advanced inspection.
   We define an additional packet header format to specify security
   inspection results and advanced inspection requests.

2.  Objective

   o  Policy configuration for consecutive inspections: NSF-triggered
      traffic steering architecture allows policy configuration and
      management of NSF triggering.  Based on the triggering policy,
      relevant network traffic can be analyzed through various NSFs in a
      composite, cooperative manner.

   o  Network traffic steering for consecutive inspection: NSF-triggered
      traffic steering architecture allows network traffic to be steered
      through multiple required NSFs based on the triggering policy.
      Moreover, the I2NSF information model for NSF facing interface
      [capability-im] requires an NSF to call another NSF for further
      inspection based on its own inspection result.  To meet this
      requirement, NSF-triggered traffic steering architecture also
      enables traffic forwarding from one NSF to another NSF.




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   o  Load balancing over NSF instances: NSF-triggered traffic steering
      architecture provides load balancing of incoming traffic over
      available NSF instances by leveraging the flexible traffic
      steering mechanism.  For this objective, it also performs dynamic
      instantiation of an NSF when there are an excessive amount of
      requests for that NSF.

3.  Terminology

   This document uses the terminology described in [RFC7665][RFC7665]
   [sfc-ns-use-cases][i2nsf-terminology][ONF-SFC-Architecture].

   o  Network Security Function (NSF): A function that is responsible
      for specific treatment of received packets.  A Network Security
      Function can act at various layers of a protocol stack (e.g., at
      the network layer or other OSI layers) [RFC7665].  Sample Network
      Security Service Functions are as follows: Firewall, Intrusion
      Prevention/Detection System (IPS/IDS), Deep Packet Inspection
      (DPI), Application Visibility and Control (AVC), network virus and
      malware scanning, sandbox, Data Loss Prevention (DLP), Distributed
      Denial of Service (DDoS) mitigation and TLS proxy.

   o  Advanced Inspection/Action: As like the I2NSF information model
      for NSF facing interface [capability-im], Advanced Inspection/
      Action means that an NSF calls another NSF for further inspection
      based on its own inspection result.

   o  Network Security Function Profile (NSF Profile): NSF Profile
      represents NSF's inspection capabilities.  Each NSF has its own
      NSF Profile to specify the type of security service it provides
      and its resource capacity etc.

   o  Network Security Function Operation Manager (NSF Operation
      Manager): NSF Operation Manager consistently manages information
      and state of NSF instances and provides NSF network access
      information to support advanced inspection request.  For example,
      the information includes the supported transport protocols, IP
      addresses, and locations for the NSF instances.  Also, NSF
      Operation Manager takes charge of dynamic management of a pool of
      NSF instances by consulting with Developer's Management System and
      load balancing over NSF instances.

   o  Packet Forwarding Header/Encapsulation: Packet Forwarding Header
      is used to forward a packet from one NSF to another for further
      inspection.  The former NSF constructs a Packet Forwarding Header
      with the NSF profile of the latter NSF and transmits it to a NSFF.
      The required fields are the action code, the number of the
      metadata, and the metadata.  In this context, the metadata is a



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      part of NSF profile.

   o  Network Security Function Forwarder (NSFF): An NSF forwarder is
      responsible for forwarding traffic to one or more connected NSFs
      according to the information carried in the packet forwarding
      encapsulation when the traffic comes back from an NSF.
      Additionally, an NSFF is responsible for transporting traffic to
      another NSFF (in the same or the different type of overlay), and
      terminating overlay inspection [RFC7665].

4.  Architecture

   This section describes an NSF-triggered traffic steering architecture
   and the basic operations of traffic steering.  It also includes
   details about each component of the architecture.

   Figure 1 describes the components of NSF-triggered traffic steering
   architecture.  Our architecture enables support a composite
   inspection of packets in transit.  According to the inspection result
   of each NSF, which is stored in the Packet Forwarding Header, the
   traffic packets could be steered to another NSF for futher detailed
   analysis.  It is also possible to reflect a high-level advanced
   inspection policy and a configuration from I2NSF User which is a
   component of the original I2NSF framwork.  Moreover, the proposed
   architecture provides load balancing, auto supplementary NSF instance
   generation, and the elimination of unused NSF instances.  In order to
   achieve these design purposes, we integrate several components to the
   original I2NSF framwork.  In the following sections, we explain the
   details of each component.






















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   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | I2NSF User                                                      |
   |              +-+-+-+-+-+-+-+-+                                    |
   |              |User/          |                                    |
   |              |App Controller |                                    |
   |              +-+-+-+^+-+-+-+-+                                    |
   |                     |                                             |
   |                     |                                             |
   +-+-+-+-+-+-+-+-+-+-+-|-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                         | Consumer-Facing Interface
                         |
   +-+-+-+-+-+-+-+-+-+-+-|-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | Security Management System                                        |
   |                     |                                             |
   |       +-+-+-+-+-+-+-v-+-+-+-+                                     |
   |       |Security Controller  |                                     |
   |       |    +-+-+-+-+-+-+    | Registration                        |
   |       |    | NSF       |    |   Interface  +-+-+-+-++-+-+-+-+     |
   |       |    | Opeation  |    |<------------>| Developer's    |     |
   |       |    | Manager   |    |              | Mgnt System    |<--+ |
   |       |    +-+-+-+-+-+-+    |              +-+-+-+-++-+-+-+-+   | |
   |       +-+-+-+-+-+-^-+-+-+-+-+                                   | |
   +-+-+-+-+-+-+-+-+-+-|-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                       | NSF-Facing Interface                        |
                       |                                             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |Security Network   |                                             | |
   |                   +-------------------------------------+       | |
   |                   |                                     |       | |
   |             +-+-+-v-+-+-+-+-+-+-+-+-+-+-+-+-+-+         |       | |
   |             |  +---------+       +---------+  |         |       | |
   |             |  | NSFF-1  |  ...  | NSFF-n  |  |         |       | |
   |             |  +---------+       +---------+  |         |       | |
   |             +-+-+-+-+-+-+-+-^-+-+-+-+-+-+-+-+-+         |       | |
   |                             |                           |       | |
   |       +-+-+-+-+-+-+-+-+-+-+-v-+-+-+-+-+-+-+-+-+-+-+--+  |       | |
   |       |  +---------+  +---------+       +---------+  |<-+       | |
   |       |  |  NSF-1  |  |  NSF-2  |  ...  |  NSF-m  |  |          | |
   |       |  +---------+  +---------+       +---------+  |<---------+ |
   |       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+--+            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


           Figure 1: NSF-triggered Traffic Steering Architecture







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4.1.  NSF Operation Manager

   NSF Operation Manager is a core component in our system.  It is
   responsible for the following three things: (1) Maintaining the
   information of every available NSF instance such as IP address,
   supported transport protocol, NSF profile, and load status. (2)
   Responding the queries of available NSF instances from NSFF so as to
   help to conduct advanced inspection relevant to a given NSF profile.
   (3) Requesting Developer's Management System for the dynamic
   instantiation of supplementary NSF instances to avoid service
   congestion or the elimination of an existing NSF instance to avoid
   resource waste.  As Figure 1 describes, NSF Operation Manager is a
   sub-module of Security Controller.

   Whenever a new NSF instance is registered, Developer's Management
   System passes the information of the registered NSF instance to NSF
   Operation Manager, so NSF Operation Manager maintains a list of the
   information of every available NSF instance.  NSF Operation Manger
   will receive the request packet containing NSF profile for advanced
   inspection from NSFF.  Once receiving a query of a certain NSF
   profile from NSFF, NSF Operation Manager searches for all the
   available NSF instances applicable for that NSF profile and then
   finds the best instance with selection criteria like location and
   load status.  After finding the best instance, it returns the search
   result to NSFF.

   In our system, each NSF instance periodically reports its load status
   to NSF Operation Manager.  Based on such reports, NSF Operation
   Manager updates the information of the NSF instances and manages the
   pool of NSF instances by requesting Developer's Management System for
   the additional instantiation or elimination of the NSF instances.
   Consequently, NSF Operation Manager enables efficient resource
   utilization by avoiding congestion and resource waste.

4.2.  Developer's Management System

   We extend Developer's Management System for additional
   functionalities as follows.  As mentioned above, NSF Operation
   Manager requests Developer's Management System to create additional
   NSF instances when the existing instances of that NSF are congested.
   On the other hand, when there are an excessive number of instances
   for a certain NSF, NSF Operation Manager requests Developer's
   Management System to eliminate some of the NSF instances.  As a
   response to such requests, Developer's Management System creates
   and/or removes NSF instances.  Once it creates a new NSF instance or
   removes an existing NSF instance, the changes must be notified to NSF
   Operation Manager.




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4.3.  Packet Forwarding Header


   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | Outer Encapsulation | Packet Forwarding Header| Origin Packet |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                        /                           \
             +---------+                             +-----------+
            /                                                     \
           /                                                       \
          +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
          | Action Code | SpecInfo Num| SpecInfo-0| ... | SpecInfo-n|
          +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


                 Figure 2: Packet Forwarding Header Format

   Packet Forwarding Header is used to convey inspection result and
   required inspection to an NSFF, so it has variable length of fields
   like Figure 2.  It contains fixed Action and the SpecInfo Num fields
   and variable SpecInfo fields.  Action field has a value out of
   "allow", "deny", "advanced", and "mirror".  SpecInfo Num field
   represents how many SpecInfos are included in the Packet Forwarding
   Header and each SpecInfo can include a part of NSF Profile which is
   required for the next inspection.  For instance, SepcInfo can be
   "syn-flood-mitigate", "udp-flood-mitigate", "content-matching-tcp"
   etc, which are the service profile of an NSF.

4.4.  Network Security Function Forwarder (NSFF)

   It is responsible for the following two functionalities: (1)
   Initiallyu forwarding the incoming traffic/packets to Network
   Security Sub-Module, as described in the I2NSF information model for
   NSF facing interface [capability-im]. (2) Forwarding the traffic/
   packets to the matched NSF with the NSF profile which is specified in
   a Packet Forwarding Header.

   An NSFF takes a gateway functionality, so it receives incoming
   traffic/packets first and attaches outer encapsulation in order to
   forward the traffic/packets to Network Sub-Module [capability-im].
   The example of Network Sub-Moudle is a firewall which performs packet
   header inspection.  This Network Security Sub-Module attaches a
   Packet Forwarding Header between the outer encapsulation and the
   original packet and specifies NSF Profile in that header so that it
   can be forwarded to Content Security Sub-Module or Mitigate Sub-
   Module for advanced inspection.

   When receiving a packet attached with a packet forwarding header of a



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   specific NSF profile, an NSFF searches for an available NSF instance
   which provides the network security service corresponding to
   (matching with) the NSF profile and forward the packet to the NSF
   instance.  If an NSF decides that the packet requires further
   inspection via another type of NSF, it constructs a packet forwarding
   header specified with (including) the NSF profile of the advanced
   NSF, attaches the header to the packet, and then sends the resulting
   packet to the NSFF.  Once receiving the packet, the NSFF checks the
   NSF profile specified in the packet forwarding header.  Then it
   searches for an NSF instance matching with the NSF profile by
   consulting with NSF Operation Manager, and finally forwards the
   packet to the NSF instance.

5.  Use Cases

   This section introduces two use cases for the NSF-triggered Traffic
   Steering Framework: (1) Enforcing Different NSFs Depending on a
   Packet Source's Trust Level, (2) Effective Load Balancing with
   Dynamic NSF Instantiation.

5.1.  Enforcing Different NSFs Depending on a Packet Source's Trust
      Level

   In the proposed architecture, all incoming packets initially arrive
   at the NSFF.  We assume that the current security policy forces all
   incoming packets to be by default inspected by a firewall in this
   scenario.  Thus the NSFF forwards the received packets to a firewall
   instance.  Then the firewall identifies the source of the traffic and
   evaluates the trust level of the source.  If the traffic comes from a
   trusted source, it is likely to be benign.  In this case, the traffic
   is just forwarded to the destination without further detailed
   inspection via different types of NSFs as illustrated in
   Figure 3.(a).  Otherwise if the traffic comes from an untrusted
   source, the firewall attaches a packet forwarding header including
   the NSF profile corresponding to DPI to the packet and returns the
   resulting packet to the NSFF.  Once receiving the packet, the NSFF
   forwards the packet to the DPI instance which will perform detailed
   inspection for the packet payload.  Figure 3.(b) illustrates this
   case.












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   +-+-+-+-+-+            +-+-+-+-+-+            +-+-+-+-+-+-+-+
   | Source  |----------->| Firewall|----------->| Destination |
   +-+-+-+-+-+            +-+-+-+-+-+            +-+-+-+-+-+-+-+

             (a) Traffic Flow of Trusted Source


   +-+-+-+-+-+     +-+-+-+-+-+     +-+-+-+-+-+     +-+-+-+-+-+-+-+
   | Source  |---->| Firewall|---->|   DPI   |---->| Destination |
   +-+-+-+-+-+     +-+-+-+-+-+     +-+-+-+-+-+     +-+-+-+-+-+-+-+

             (b) Traffic Flow of Untrusted Source


      Figure 3: Different Path Allocation according to Traffic Source

5.2.  Effective Load Balancing with Dynamic NSF Instantiation

   In a large-scale network domain, there typically exist a large number
   of NSF instances that provide various security services.  It is
   possible that a specific NSF instance experiences an excessive amount
   of traffic beyond its capacity.  In this case, it is required to
   allocate some of the traffic to another available instance of the
   same NSF.  If there are no additional instances of the same NSF
   available, we need to create a new NSF instance and then direct the
   subsequent traffic to the new instance.  In this way, we can avoid
   service congestion and achieve more efficient resource utilization.

   This process is commonly called load balancing.  In our proposed
   architecture, NSF Operation Manager performs periodic monitoring of
   the load status of available NSF instances.  In addition, it is
   possible to dynamically generate a new NSF instance through
   Developer's Management System.  With these functionalities along with
   the flexible traffic steering mechanism, we can eventually provide
   load balancing service.

   The following describes the detailed process of load balancing when
   congestion occurs at the firewall instance:

   1.  NSF Operation Manager detects that the firewall instance is
       receiving too much requests.  Currently, there are no additional
       firewall instances available.

   2.  NSF Operation Manager requests Developer's Management System to
       create a new firewall instance.

   3.  Developer's Management System creates a new firewall instance and
       then registers the information of the new firewall instance to



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       NSF Operation Manager.

   4.  NSF Operation Manager updates the SFC Information Table to
       reflect the new firewall instance, and notifies NSF and NSFF of
       this update.

   5.  According to the new forwarding information, the NSFF forwards
       the subsequent traffic to the new firewall instance.  As a
       result, we can effectively alleviate the burden of the existing
       firewall instance.

6.  Security Considerations

   To enable network security function chaining in the I2NSF framework,
   we adopt the additional components in the SFC architecture.  Thus,
   this document shares the security considerations of the SFC
   architecture that are specified in [RFC7665] for the purpose of
   achieving secure communication among components in the proposed
   architecture.

7.  Acknowledgements

   This work was supported by Institute for Information & communications
   Technology Promotion(IITP) grant funded by the Korea government(MSIP)
   (No.R-20160222-002755, Cloud based Security Intelligence Technology
   Development for the Customized Security Service Provisioning).

   This document has greatly benefited from inputs by Linda Dunbar,
   Susan Hares, and Hyoungshick Kim.

8.  References

8.1.  Normative References

   [RFC7665]               Boucadair, M. and C. Jacquenet, "Software-
                           Defined Networking: A Perspective from within
                           a Service Provider Environment", RFC 7665,
                           March 2014.

   [sfc-ns-use-cases]      Wang, E., Leung, K., Felix, J., and J. Iyer,
                           "Service Function Chaining Use Cases for
                           Network Security",
                           draft-wang-sfc-ns-use-cases-01 (work in
                           progress), March 2016.







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8.2.  Informative References

   [RFC7498]               Quinn, P. and T. Nadeau, "Problem Statement
                           for Service Function Chaining", RFC 7498,
                           April 2015.

   [capability-im]         Xia, L., Zhang, D., Li, K., Basile, C., Lioy,
                           A., Lopez, D., Lopez, E., Bouthors, N., and
                           L. Fang, "Information Model of Interface to
                           Network Security Functions Capability
                           Interface",
                           draft-xibassnez-i2nsf-capability-00 (work in
                           progress), November 2016.

   [i2nsf-framework]       Lopez, E., Lopez, D., Dunbar, L., Strassner,
                           J., and R. Kumar, "Framework for Interface to
                           Network Security Functions",
                           draft-ietf-i2nsf-framework-04 (work in
                           progress), October 2016.

   [i2nsf-problem]         Hares, S., Dunbar, L., Lopez, D., Zarny, M.,
                           Jacquenet, C., and J. Jeong, "I2NSF Problem
                           Statement and Use cases",
                           draft-ietf-i2nsf-problem-and-use-cases-03
                           (work in progress), November 2016.

   [i2nsf-terminology]     Hares, S., Strassner, J., Lopez, D., Xia, L.,
                           and H. Birkholz, "Interface to Network
                           Security Functions (I2NSF) Terminology",
                           draft-ietf-i2nsf-terminology-02 (work in
                           progress), October 2016.

   [ONF-SFC-Architecture]  ONF, "L4-L7 Service Function Chaining
                           Solution Architecture", June 2015.

















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Authors' Addresses

   Sangwon Hyun
   Department of Software
   Sungkyunkwan University
   2066 Seobu-Ro, Jangan-Gu
   Suwon, Gyeonggi-Do  16419
   Republic of Korea

   Phone: +82 31 290 7222
   Fax:   +82 31 299 6673
   EMail: swhyun77@skku.edu
   URI:   http://imtl.skku.ac.kr/


   Jaehoon Paul Jeong
   Department of Software
   Sungkyunkwan University
   2066 Seobu-Ro, Jangan-Gu
   Suwon, Gyeonggi-Do  16419
   Republic of Korea

   Phone: +82 31 299 4957
   Fax:   +82 31 290 7996
   EMail: pauljeong@skku.edu
   URI:   http://iotlab.skku.edu/people-jaehoon-jeong.php


   SangUk Woo
   Department of Software
   Sungkyunkwan University
   2066 Seobu-Ro, Jangan-Gu
   Suwon, Gyeonggi-Do  16419
   Republic of Korea

   Phone: +82 31 290 7222
   Fax:   +82 31 299 6673
   EMail: suwoo@imtl.skku.ac.kr,
   URI:   http://imtl.skku.ac.kr/index.php?mid=member_student












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   YunSuk Yeo
   Department of Software
   Sungkyunkwan University
   2066 Seobu-Ro, Jangan-Gu
   Suwon, Gyeonggi-Do  16419
   Republic of Korea

   Phone: +82 31 290 7222
   Fax:   +82 31 299 6673
   EMail: yunsuk@imtl.skku.ac.kr,
   URI:   http://imtl.skku.ac.kr/index.php?mid=member_student


   Jung-Soo Park
   Electronics and Telecommunications Research Institute
   218 Gajeong-Ro, Yuseong-Gu
   Daejeon  305-700
   Republic of Korea

   Phone: +82 42 860 6514
   EMail: pjs@etri.re.kr






























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