Development of IPv6-IPv4 Translation Mechanisms for SIP-based VoIP Applications

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Development of IPv6-IPv4 Translation Mechanisms
for SIP-based VoIP Applications

• Advisor Dr. Kai-Wei Ke
• Speaker Wei-Ying Huang

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Outline

• Introduction
• BIA
• BIS
• SLT
• SIPv6 Translator
• Implementation

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Introduction

• SIP VoIP application is an important driving
  force to promote IPv6.
• This paper presents the deployment of two
  IPv6-IPv4 translation mechanisms (i.e.,
  Socket-layer Translator and SIPv6 Translator) for
  SIP VoIP applications.

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IPv4/IPv6 Transition Mechanisms

• Dual Stack
• Reduce the cost invested in transition by running
  both IPv4/IPv6 protocols on the same machine .
• Tunneling
• Reduce the cost in wiring by re-using current
  IPv4 routing infrastructures as a virtual link.
• Translation
• Allow IPv6 realm to access the rich contents
  already developed on IPv4 applications

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Dual Stack

• Dual stack hosts run both the IPv4 and the IPv6
  in Network Layer.

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Tunneling
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Translation

• Translation Mechanism is used when the IPv4
  network connects to IPv6 network

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Translation (cont)

• Install between the IPv4 network and IPv6
  network.
• NAT-PT (Network Address Translation and Protocol
  Translation)
• ALG (Application-Level-Gateway)
• SIIT (Stateless IP/ICMP Translation)
• Install on host computer
• BIS (Bump-In-the-Stack)
• BIA (Bump-In-the-Application)

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BIA (Bump-in-the-API)

• Allows the dual stack hosts to communicate with
  other IPv6 hosts using existing IPv4
  applications.
• Provides the translation method between the IPv4
  APIs and IPv6 APIs.
• The goal is simply achieved without IP header
  translation.

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BIA (cont)

• The BIA technique inserts an API translator
  between the socket API module and the TCP/IP
  module in the dual stack hosts.

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Components of BIA

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Components of BIA (cont)

• Function Mapper
• It translates an IPv4 socket API function into an
  IPv6 socket API function.
• Name Resolver
• It returns a proper answer in response to the
  IPv4 application's request.
• Address Mapper
• It internally maintains a table of the pairs of
  an IPv4 address and an IPv6 address.

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Behavior of BIA

• ---gt A DNS message for name resolving created by
  the applications and the name resolver in the API
  translator.
• gt An IPv4 address request to and reply from
  the address mapper for the name resolver and the
  function mapper.
• gt Data flow by socket API functions created by
  the applications and the function mapper in the
  API translator.

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15

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BIS (Bump-in-the-Stack)

• Between a TCP/IPv4 module and network card driver
  modules and translate IPv4 into IPv6 and vice
  versa.

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Components of BIS

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Components of BIS (cont)

• Translator
• It translates IPv4 into IPv6 using the IP
  conversion mechanism
• Extension Name Resolver
• This action is the same as Name Resolver in BIA
• Address mapper
• This action is the same as Address mapper in BIA

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SLT (Socket-layer Translator)

• BIS and BIA can successfully translate NAT
  friendly protocols (e.g. HTTP and TELNET)
• Both of them only process the network-layer and
  transport-layer header information.
• Some protocols such as FTP and SIP contain IP
  address and port information in the
  application-layer headers

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SLT (cont)

• The SLT translates NAT friendly protocols by
  redirecting IPv4 socket functions to IPv6.
• For non-NAT friendly protocols (e.g., FTP and
  SIP), we implement Application Layer Gateways
  (ALGs) and ALG Manager.
• ALGs and ALG Manager allow the dual-stack hosts
  to access IPv6 resources through IPv4
  applications without any modification.

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Components of SLT

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Components of SLT (cont)

• BIA Component
• Operates the same functions as the BIA mechanism
• ALG-Manager
• The ALG-Manager forwards the parameters to
  SIP-ALG or FTP-ALG by port number.

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Components of SLT (cont)

• FTP-ALG
• Translate both IP/port information in the FTP
  messages and the FTP commends.

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Components of SLT (cont)

• SIP-ALG
• The SIP-ALG modifies IP address and port number
  information in SIP From, To, Via, Contact header
  fields and Session Description Protocol (SDP) c
  and m fields.

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Comparison of Transition Mechanisms

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SIPv6 Translator

• Problem SIP UA cannot directly communicate with
  IPv4-based SIP UA.

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Components of SIPv6 Translator

• NIC (Network interface controllers)
• One NIC connects to IPv6 networks and the other
  connects to IPv4 networks.
• Packet Forwarding Engine
• Intercepts the incoming packets, forwards to the
  NAT-PT Component.
• Sends the translated packets to the destination
  NICs.

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Components of SIPv6 Translator (cont)

• NAT-PT Component
• Consists of the Stateless IP/ICMP Translation
  (SIIT) component and an IPv6-IPv4 mapping table.
• Performs IPv6-IPv4 translation for IP and ICMP
  headers.
• ALG-Manager
• Dispatches the incoming packet to DNS-ALG and
  SIP-ALG according to the transport port number.
  (Port 53-gtDNS, Port 5060-gtSIP)

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Components of SIPv6 Translator (cont)

• DNS-ALG
• Translates an IPv4 (or IPv6) DNS query to an IPv6
  (or IPv4) DNS query and instructs the NAT-PT
  Component to builds the IPv6-IPv4 mapping.
• SIP-ALG
• Translates the IP/port-related fields in the SIP
  and SDP header and instructs the NAT-PT Component
  to builds IPv6-IPv4 mapping.

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SLT Performance

• Measure the NCTU SLT performance on FTP
  applications transfer.
• environment
• Server vsftpd running on Linux Fedora
• Client SmartFTP running on Windows XP
• Network Bandwidth 100Mbps Ethernet
• Files size 10KB to 2GB

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Transmission Delay (sec)
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Transmission Delay with and without NCTU SLT
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Evaluation of SLT and SIPv6 Translator Deployment
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SIP/SDP header fields that are checked by SIP
VoIP devices
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Conclusions

• Present two IPv6-IPv4 translation mechanisms
  (i.e., SLT and SIPv6 Translator) and their
  deployment.
• SLT
• Translate a SIPv4 UA to IPv6 version.
• SIPv6 Translator
• Assist the SIPv6 UA to interwork with all SIPv4
  UAs and PSTN gateways on NTP VoIP platform.
• SLT only translate SIPv4 UA to IPv6 version, but
  maybe can try to translate SIPv6 UA to IPv4
  version in future work.

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Reference

• Whai-En Chen Wu, Q Development and Deployment
  of IPv6-Based SIP VoIP Networks IEEE CNF 31-04
  Jan. 2005 Page(s)76 - 79 Digital Object
  Identifier 10.1109/SAINTW.2005.1619982
• Whai-En Chen, Chia-Yung Su and Yi-Bing Lin.NCTU
  SLT A Socket-layer Translator forIPv6-IPv4
  Translation. Accepted and to appear inIEEE
  Communications Letters.
• S. Lee, M-K. Shin, Y-J. Kim, E. Nordmark,
  A.Durand. Dual Stack Hosts Using
  Bump-in-the-API(BIA). IETF RFC3338. October
  2002.
• K. Tsuchiya, H. Higuchi, Y. Atarashi. Dual Stack
  Hosts using the Bump-In-the-Stack Technique
  (BIS). IETF RFC2767. February 2000.

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NAT-PT
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