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This paper discusses the autoconfiguration of recursive DNS servers in HMIPv6, optimizing DNS name resolution through RA-based DNS discovery. It presents benefits of using local RDNSS servers and analyzes resolution delays.
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VTC2003-Fall The Autoconfiguration of Recursive DNS Server and the Optimization of DNS Name Resolutionin Hierarchical Mobile IPv6 Jaehoon Jeong, Kyeongjin Lee, Jungsoo Park, Heecheol Lee, Hyoungjun KimETRI{paul,leekj,pjs,hclee_shep,khj}@etri.re.kr http://www.adhoc.6ants.net/~paulThis paper and presentation material are posted on the above site. VTC2003-Fall
Contents • Motivation • Related Work • Main Idea • Benefit of using Local Recursive DNS Server • Current DNS Service Scenario in HMIPv6 • Suggested DNS Service Scenario in HMIPv6 • DNS Autoconfiguration and Optimization in HMIPv6 • Analysis of the Delay needed for DNS Name Resolution • Conclusion VTC2003-Fall
Motivation • The current DNS name resolution depends on fixed recursive DNS server(s) preconfigured in the host if we don’t use DHCPv6. • But, this is unsuitable for the mobile IPv6 environment. • In the respect of DNS name resolution time. • What solutions are there to save DNS name resolution time? • This paper suggests one of the possible solutions. VTC2003-Fall
Related Work: DNS Discovery • DNS Autoconfiguration in DHCPv6 • DNS Discovery throuth DHCPv6 DNS Option • Weak Point • It needs some delay for the discovery of DHCPv6 server and the additional message exchange. • Well-known Site-local Unicast Addresses for Recursive DNS Servers • Three well known addresses are defined to configure stub resolvers on IPv6 nodes • Weak Point • Every domain should have at least one recursive DNS server with well-known site-local addresses configured and supportsite-local address routing. VTC2003-Fall
Main Idea: Optimized DNS Name Resolution through RA-based DNS Discovery • Autoconfiguration of recursive DNS server (RDNSS) • Through RA-based DNS discovery, a mobile node can configure the address of recursive DNS server(s) placed in the visited network statelessly. • Optimization of DNS name resolution • It is possible by using the local recursive DNS server placed in the visited network instead of that placed in the home network. • The scope of this paper • Hierarchical Mobile IPv6 Network • But the idea of this paper can be applied to mobile IPv6 network or normal IPv6 network. VTC2003-Fall
Benefit of using Local Recursive DNS Server (1/2) • Test Environment • A host performs the DNS resolution of another host’s DNS name through three DNS servers • Resolution Delay for each Recursive DNS Server (RDNSS) • Sample Packet# : 10 VTC2003-Fall
Benefit of using Local Recursive DNS Server (2/2) The figure shows the Resolution Delay of a Host DNS Name through3 Recursive DNS Servers-> The result informs us of the benefit of using local RDNSS! VTC2003-Fall
RDNSS1 Current DNS Service Scenario in HMIPv6 (1/2) DNS Server(DNSS) Web Server(WS) RDNSS : Recursive DNS Server 3 Internet Home Agent(HA) Mobility Anchor Point(MAP) 2 5 1 RDNSS2 4 MN VTC2003-Fall Home Network Foreign Network
RDNSS1 Current DNS Service Scenario in HMIPv6 (2/2) DNS Server(DNSS) Dog-legged DNS Name Resolution Web Server(WS) 3 Internet Home Agent(HA) Mobility Anchor Point(MAP) 2 5 4 RDNSS2 1 MN VTC2003-Fall Home Network Foreign Network
RDNSS1 Suggested DNS Service Scenario inHMIPv6 DNS Server(DNSS) Optimization of DNS Name Resolution Web Server(WS) 3 Internet Home Agent(HA) Mobility Anchor Point(MAP) 5 2 1 RDNSS2 4 MN VTC2003-Fall Home Network Foreign Network
DNS Autoconfiguration and Optimization in HMIPv6 • HMIPv6 Extension • The address of Recursive DNS Server (RDNSS) is advertised into MAP domain by MAP and Routers below the MAP. • Neighbor Discovery Extension • RDNSS Option, a new option of RA message, has been introduced to contain the address of Recursive DNS Server. • RDNSS Selection by the Mobile Node • RDNSS nearest from MN is selected for DNS service. • Detection of RDNSS Failure • MAP keeps the state of RDNSSes. • If any RDNSS fails, MAP announces the failure into MAP domain. VTC2003-Fall
Procedure of DNS Autoconfiguration and Format of RDNSS Option RDNSS Option in RA Message VTC2003-Fall
Analysis of the Delay needed for DNS Name Resolution 1. Dog-legged DNS Name Resolution Time (T1) 2. Optimized DNS Name Resolution Time (T2) Difference of T1-T2 dwhere d is the distance b/w MAP & HA VTC2003-Fall
Conclusion • DNS Autoconfiguration and Optimization • Through autoconfiguration of recursive DNS server, the optimization of DNS name resolution is possible in HMIPv6 network. • RA-based DNS Discovery is the most efficient in HMIPv6. • Applicability of DNS Autoconfiguration • This scheme can be adopted in other wireless networks, such as NEMO and MANET connected to the Internet. • Refer to PIMRC2003 paper, “Name Service in IPv6 Mobile Ad-hoc Network connected to the Internet”. VTC2003-Fall