Detecting Network Attachment in IPv6 Problem Statement

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. AR1 AR2 AR3 Cell 1 Cell 2 Cell 3 AP1 AP2 AP3 Background, Movement Detection Each AR advertises the different prefix. Internet There are 3 Wireless Cell for 3 APs. A:: B:: C::

5. AR1 AR2 AR3 Link 2 Link 1 AP1 AP2 AP3 Background, Movement Detection Each AR advertises the different prefix. Internet There are 3 Wireless Cell for 3 APs. There are only 2 links. A:: B:: C:: * Link: a communication facility or medium over which nodes can communicate at the link layer

6. AR1 AR2 AR3 MN Cell 1 Cell 2 Cell 3 AP1 AP2 AP3 Background, Movement Detection 1. MN is attached to AR1 via AP1 Internet A:: B:: C::

7. AR1 AR2 AR3 MN Cell 1 Cell 2 Cell 3 AP3 AP2 AP1 Background, Movement Detection 1. MN is attached to AR1 via AP1 2. MN changes its attachment to AP2 and link change has occurred. Internet A:: B:: C::

8. AR1 AR2 AR3 MN Cell 1 Cell 2 Cell 3 AP3 AP2 AP1 Background, Movement Detection 1. MN is attached to AR1 via AP1 2. MN changes its attachment to AP2 and link change has occurred. Internet 3. MN changes its attachment to AP3 but still remains at the same link. A:: B:: C::

9. AR1 AR2 AR3 MN Cell 1 Cell 2 Cell 3 AP3 AP2 AP1 Background, Movement Detection 1. DNAv6 have to detect movement quickly when MN moves from Cell 1 to Cell2. Internet 2. MN should not falsely assume movement when MN moves from Cell 2 to Cell 3. A:: B:: C::

10. Internet AR1 AR2 N AP1 AP2 DNAv6, rough sketch 0. Node N is attached to AR1 via AP1.

11. Internet AR1 AR2 N AP1 AP2 DNAv6, rough sketch 0. Node N is attached to AR1 via AP1. 1. N make an access to AR2 via AP2, a new link-layer connection has been established. 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 - N receives a RA and checks the prefixes in it. 5.In case its IP address is no longer valid, N forms a new IP address.

12. Internet AR1 AR2 N AP1 AP2 DNAv6, rough sketch 0. Node N is attached to AR1 via AP1. 1. N make an access to AR2 via AP2, a new link-layer connection has been established. 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.

13. DNAv6 Process • 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

14. DNAv6 Methods • 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

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. Internet Router MN AP1 AP2 Multi-link Subnet Link local Addr, 2 Prefix A:: Link local Addr, 1 Prefix A:: • 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?

19. Internet Router MN AP1 AP2 Link local scope of Router Addr & Omission of Prefix information Link local Addr, 1 Prefix B:: Link local Addr, 1 Prefix A:: • 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.

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

21. Current MD implementations • Investigation Result at the Brussel ETSI