1. VTC2003-Fall1 The Autoconfiguration of Recursive DNS Server and the Optimization of DNS Name Resolution in Hierarchical Mobile IPv6 Jaehoon Jeong, Kyeongjin Lee, Jungsoo Park, Heecheol Lee, Hyoungjun Kim ETRI {paul,leekj,pjs,hclee_shep,khj}@etri.re.kr http://www.adhoc.6ants.net/~paul http://www.adhoc.6ants.net/~paul This paper and presentation material are posted on the above site. VTC2003-Fall

2. 2 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

3. VTC2003-Fall3 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.

4. VTC2003-Fall4 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 support site-local address routing.

5. VTC2003-Fall5 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.

6. VTC2003-Fall6 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 Hop# MIN Delay [ms] MAX Delay [ms] Average Delay [ms] RDNSS(ETRI)3374.9 RDNSS(SNU)18143225.6 RDNSS(IETF)24245304259.9

7. VTC2003-Fall7 Benefit of using Local Recursive DNS Server (2/2) The figure shows the Resolution Delay of a Host DNS Name through 3 Recursive DNS Servers -> The result informs us of the benefit of using local RDNSS!

8. VTC2003-Fall8 Current DNS Service Scenario in HMIPv6 (1/2) Internet Mobility Anchor Point (MAP) MN RDNSS2 DNS Server (DNSS) Foreign NetworkHome Network Home Agent (HA) Web Server (WS) 5 1 2 3 4 RDNSS : Recursive DNS Server

9. VTC2003-Fall9 Current DNS Service Scenario in HMIPv6 (2/2) Internet Mobility Anchor Point (MAP) RDNSS2 DNS Server (DNSS) Foreign NetworkHome Network Home Agent (HA) Web Server (WS) 5 1 3 4 MN 2 Dog-legged DNS Name Resolution

10. VTC2003-Fall10 Suggested DNS Service Scenario in HMIPv6 Internet Mobility Anchor Point (MAP) RDNSS2 DNS Server (DNSS) Foreign NetworkHome Network Home Agent (HA) Web Server (WS) 5 1 3 MN 2 4 Optimization of DNS Name Resolution

11. VTC2003-Fall11 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.

12. VTC2003-Fall12 Procedure of DNS Autoconfiguration and Format of RDNSS Option RDNSS Option in RA Message

13. VTC2003-Fall13 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  d where d is the distance b/w MAP & HA

14. VTC2003-Fall14 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”.Name Service in IPv6 Mobile Ad-hoc Network connected to the Internet