DHCP-based Fast Handover protocol

1. DHCP-based Fast Handover protocol NTT Network systems laboratories 2005. 3. 8 Takeshi Ogawa draft-ogawa-fhopt-00.txt 62nd IETF - Minneapolis Mobopts RG

2. Outline • Motivation • Problem statement • Proposed protocol • HO sequence example • Test system current situation

3. Motivation • IP layer Fast Handover function is needed for real time application. • A protocol, that realize FH function inexpensive and that will be available soon, is required. • FMIP(MIPSHOP) and Fast RA(DNA) can reduce IP layer HO time. • However, there are 4 problems in both method.

4. Problems of FMIP and Fast RA (1/3) • Many facilities to be up graded (expensive) With FMIP or Fast RA, all of ARs in service area MUST be up graded, and the ARs need to exchange messages for HOs. So, the number of facilities to be upgraded may be numerous, and connectivity between every pair of different venders and kinds of ARs shall be assured. The fewer facilities to be upgraded the better, and less correlation between facilities is better.

5. Problems of FMIP and Fast RA (2/3) 2. Handling of stateful address (not defined yet) Plain IP nodes (usually) uses DHCP to get stateful IP addresses. With FMIP, a new stateful IP address to be used after handover is distributed by PrRtAdv message (introduced in FMIP). We suppose unified method is better. With Fast RA, there is no function to distribute stateful IP addresses quickly. ... as long as I know.

6. Problems of FMIP and Fast RA (3/3) • Security association (SA) set-up method between MN and NAR. (being discussed in Mobopts now) With FMIP, FBU messages MUST be authenticated by AR to prevent service from being stolen. However, the SA set–up method for it is not defined, it might take long time... 4. How to reduce L2 HO time. (not defined yet) In the FMIP and the Fast RA, there is no function to reduce the L2 HO processing time.

7. Proposed DHCP-based FH protocol With the protocol, DHCP server sends "Fast Handover Options" to MN before handovers. Those options include essence of FMIP, link layer and IP layer information, to be used by the MN after handovers, so that the MN can complete HO sequence quickly. CN CN Fast HO function HA HA IPv6 network Fast HO function IPv6 network DHCP server AR AR AR AR AR AR AR AR MN MN Current FMIP and Fast RA Proposed method

8. It solves the 4 problems (1/2) It is based on DHCP so, • Facilities to be up graded • Fewer than FMIP and Fast RA (inexpensive) • With this protocol plain access routers (if they have the DHCP relay function) can be used. • 2. Handling of stateful address • Unified in DHCP manner. (defined) • SA set-up method • Not problem with this protocol. • SA between MN and DHCP server can be used after handover. (no problem) • (usually the DHCP server is not changed)

9. It solves the 4 problems (2/2) Furthermore, 4. L2 HO time Reduced by sending L2 information to MN before HO. (defined (wireless LAN)) For example, wireless LAN channel number used by new APs are sent to a MN, and the MN can search for the notified channel only instead of all channels and can reduce layer 2 HO time.

10. Seamless HO for MIP sequence example with this protocol MN （DHCP client） PAR DHCP server HA CN Fast Handover options DHCP REQUEST/REPLAY BU/BA User’s IP packets Tunnel Bufferring (Moor) HO trigger Search available channel only BU/BA (request buffering) Layer2 switch It could be less than a hundred millisecond(?) (wireless LAN to wireless LAN HO) 802.11i NAR Access authentication BU/BA (request sending) User’s IP packets Opt DAD (Moor) NS（DAD) Standard messages DHCP CONFIRM/REPLY No need if the MN is still in same DHCP-domain Proposed messages Defined in other draft

11. Test system implementing status We are currently implementing the test system in Linux. The basic protocol functions are to be checked by the end of March. MobileIPv6 HomeAgent (HA) DHCPv6 server CN L2SW CISCO 3745 L2SW L2SW AP1 AP2 AP3 MN

12. A DHCP-based FH protocol is proposed. Main functions of it are ported from FMIP. It could offer FH function inexpensive and would be available soonif you give me a help. Any comments welcome! Thank you in advance! Summary

13. Annex

14. Functions of proposed method It has 5 main Functions. (A), (B) and (C) are almost the same as FMIP, but (D) and (E) are new functions that FMIP does not offer.

15. Functions of proposed protocol • RA proxying function and (B) DHCP proxying function. Fast Handover Options carry information to MNs on old links, which are to be carried by the standard RA and DHCP IA options on new links, and MNs do not need to exchange RS/RA and DHCP solicit messages on new links.

16. Functions of proposed protocol (C) Movement detection function A unique ID for link (L3-information-ID) is introduced. Fast Handover Options carry new AP's ID (e.g., BSSID) and its corresponding L3-information-ID to MNs on old links, and MNs can detect movement using those IDs without NUD on a new link.

17. Functions of proposed protocol (D) Layer 2 information distribution function Fast Handover Options also carry new link information, for example, wireless LAN channel number used by new APs, and MNs can search for the notified channel only instead of all channels and can reduce layer 2 handover.

18. Functions of proposed protocol (E) Confirm Message solicit function A unique ID for DHCP-domains is also introduced. Fast Handover Options carry the IDs, and a MN can know whether it has entered a new DHCP-domain after handover. If the MN is still in the same DHCP-domain, it does not need to send a confirm Message to a DHCP server on a new link.

19. Functions not supported *Smooth HO function Tunnel Buffering may be applied *Prevent interruption during DAD Opt DAD may be applied. *Quick user authentication To be discussed but out of scope of this protocol now. *Context Transfer of AR This protocol can not offer this function.