1. Detecting Network Attachment in IPv6 Problem Statement JinHyeock Choi, Samsung AIT jinchoe@samsung.com 2003.11.11

2. Contents Background/ Movement Detection DNAv6 Overview DNAv6 Process DNAv6 Methods DNAv6 Problems DNAv6 Next Steps & Requirement

3. Background, Movement Detection

4. Internet AR1 AP1AP2 AR2AR3 AP3 Cell 1Cell 2Cell 3 There are 3 Wireless Cell for 3 APs. Each AR advertises the different prefix. A::B::C:: Background, Movement Detection

5. Internet AR1 AP1AP2 AR2AR3 AP3 There are only 2 links. Link 1 Link 2 There are 3 Wireless Cell for 3 APs. Each AR advertises the different prefix. A::B::C:: Background, Movement Detection * Link: a communication facility or medium over which nodes can communicate at the link layer

6. Internet AR1 AP1AP2 AR2AR3 AP3 1. MN is attached to AR1 via AP1 Cell 1Cell 2Cell 3 MN A::B::C:: Background, Movement Detection

7. Internet AR1 AP1AP2 AR2AR3 AP3 1. MN is attached to AR1 via AP1 2. MN changes its attachment to AP2 and link change has occurred. MN Cell 1Cell 2Cell 3 A::B::C:: Background, Movement Detection

8. Internet AR1 AP1AP2 AR2AR3 AP3 1. MN is attached to AR1 via AP1 2. MN changes its attachment to AP2 and link change has occurred. Cell 1Cell 2Cell 3 MN A::B::C:: Background, Movement Detection 3. MN changes its attachment to AP3 but still remains at the same link.

9. Internet AR1 AP1AP2 AR2AR3 AP3 Cell 1Cell 2Cell 3 MN A::B::C:: Background, Movement Detection 1. DNAv6 have to detect movement quickly when MN moves from Cell 1 to Cell2. 2. MN should not falsely assume movement when MN moves from Cell 2 to Cell 3.

10. 0. Node N is attached to AR1 via AP1. DNAv6, rough sketch Internet AR1 N AP1AP2 AR2

11. 0. Node N is attached to AR1 via AP1. 2. N receives a hint that link change may have occurred. 3. N checks whether it still is at the same link. - If so, it can still reach its current AR and don’t need to perform DNAv6 anymore. 4. If not, a node discovers a new AR with the prefix information. DNAv6, rough sketch - N receives a RA and checks the prefixes in it. 5. In case its IP address is no longer valid, N forms a new IP address. Internet AR1 N AP1AP2 AR2 1. N make an access to AR2 via AP2, a new link-layer connection has been established.

12. DNAv6, rough sketch Internet AR1 N AP1AP2 AR2 0. Node N is attached to AR1 via AP1. 2. N receives a hint that link change may have occurred. 3. N checks whether it still is at the same link. - If so, it can still reach its current AR and don’t need to perform DNAv6 anymore. 4. If not, a node discovers a new AR with the prefix information. - N receives a RA and checks the prefixes in it. 5. In case its IP address is no longer valid, N forms a new IP address. 1. N make an access to AR2 via AP2, a new link-layer connection has been established.

13. Step1: Hint Step2: Detecting the link change. – Checking the reachability of current default router. Step3: Router Discovery with the prefix information. – Checking the validity of current IP address DNAv6 Process

14. Step1: Hint – Link layer hint – New RA message – RA beaconing Step2: Checking the Link change. – Checking the reachability of current default router. NUD like (3 NSs) 1 NS and timeout RA beaconing Step3: Router Discovery with the prefix information. – RS/ RA exchange DNAv6 Methods

15. DNAv6 Problems No means to represent a link – In RA message, neither router address nor prefixes can do it. – Link-layer hint can’t detect Link change by itself. The ambiguity of RA information – Link local scope of router address – Prefix omission The delay to check the reachability of current AR – It’s difficult to detect something is NOT there. – Roughly 3 secs for NUD Random Delay in RS/ RA exchange No agreed way to do DNAv6

16. DNAv6 Goals with Requirements Update a RA message format, which – can represent a link – doesn’t have performance degrading ambiguities. Specify a operational procedure, which – can quickly detect link change – can quickly receive a RA with the prefix information. Define a DNAv6 scheme such that – Fast: low time delay – Precise/ Secure: Little error – Efficient: limit signaling (NS/NA or RS/RA)

17. Appendix: MD Pathologies Multi-link Subnet Link local scope of Router Addr with Omission of Prefix Information ECS without L2 support Current MD implementations (from ETSI interoperability test)

18. Multi-link Subnet Router Internet Prefix A:: AP1AP2 MN Assume Router has two interface with two different link local addresses. To each interface, an AP is attached. Through each interface, the Router advertises the same Prefix A:: without setting L bit. When a MN moves from AP1 to AP2, it changes its default router address but can keep using its CoA. Should we design DNAv6 to accommodate this case or can we safely ignore this as a pathological exception? Link local Addr, 1 Link local Addr, 2

19. Link local scope of Router Addr & Omission of Prefix information Router Internet Prefix A:: Prefix B:: AP1AP2 MN Assume Router has two interface with the same link local addresses. To each interface, an AP is attached. Through each interface, the Router advertises two different prefixes, A:: & B:: without setting L bit. Assume a MN has moved from AP1 to AP2. If a router omitted prefix from its RA, MN can’t detects movement with RA messages. Link local Addr, 1 Link local Addr, 1

20. Internet R1R2 R1 advertises On-Link Prefix A:: MN is implemented to send BU whenever hint occurs. MN keeps sending BUs whenever a RA arrives. R2 advertises On-Link Prefix B:: ECR without L2 support AP1 MN

21. Current MD implementations Investigation Result at the Brussel ETSI