HMIPv6

1. HMIPv6

2. Mobile-IPv6 • Modes for communications between the mobile node and a correspondent node • Bidirectional tunneling • Does not require Mobile IPv6 support from the correspondent node • “Route Optimization“ • Requires the mobile node to register its current binding at the correspondent node. • Packets from the correspondent node can be routed directly to the care-of address of the mobile node

3. Internet or Intranet “ ” Mobile-IPv6 using Reverse Tunneling Mobile Node Access Router Access Router Corresponding Node Home Agent

4. Internet or Intranet “ ” Mobile-IPv6 using Route Optimization Mobile Node Access Router Access Router Corresponding Node Home Agent

5. Binding Updates Link UP Internet or Intranet “ ” Mobile-IPv6 Binding Updates x Mobile Node Access Router Access Router Corresponding Node Home Agent

7. Drawbacks of Mobile IPv6 • Mobile IPv6 • Reacts after L2 movement • Introduces a period of service disruption after L2 movement until signaling is completed • Performance depends on Mobile IP registration time and MH-HA distance • Optimization Schemes • Fast Handover for Mobile IPv6 • Anticipates Mobile IP messaging (before L2 movement) • Hierarchical Mobile IPv6 • Reduces MN to HA round trip delay • Reduces the number of messages (ratio transmission efficiency)

8. 11.2 Hierarchical Mobile IPv6 (HMIPv6) –RFC4140 • HMIPv6 requires new entities called Mobility Anchor Points (MAPs) in the visiting network. • MAP acts as a local home agent. • It is usually implemented on a router. • Mobile nodes have to perform binding updates to home agents and correspondent nodes only when it firstly enters into a MAP domain. • When mobile nodes move inside the MAP domain, they do not have to perform binding updates to home agent and correspondent nodes. Binding updates to the MAP are only needed. • If HMIPv6 is not provided in a visited network, a mobile node performs normal MIPv6 protocol and gets connectivity to Internet.

9. Figure 11-1. Hierarchical Mobile IPv6. Figure 11-1. Hierarchical Mobile IPv6.

10. Two types of care-of address are defined for HMIPv6 • on-link care-of address (LCoA) is a CoA used as a CoA in the binding update to MAP. • regional care-of address (RCoA) is a CoA in the binding update to home agent and correspondent nodes in case of route optimization. • Only RCoA is registered at the mobile node's home agent and correspondent nodes. • MAPs keep binding between RCoA and LCoA • home agents keep binding between mobile node's home address and the primary care-of address (RCoA)

11. Movements within MAP are not informed to outer nodes of MAP. • Only movements between MAPs are notified to home agent, which reduces mobile signaling message exchanges between inner MAP domain and outer network.

12. 11.2.2 Terminology • Access Router (AR): mobile node's default router. • On-link care-of address (LCoA): LCoA is an address obtained from the visited network via stateless address configuration mechanism. • Prefix information is learned from Router Advertisement message from a default router, AR. • In original MIPv6, this address type is simply called care-of address. • Mobility Anchor Point (MAP): MAP is a special router located in a visited network by a mobile node. • MAP operates as a local home agent. • Multiple MAPs may exist in a visited network. • MAP domain: MAP domain is determined by Router Advertisement messages from access routers, which contain MAP information.

13. 11.2.2 Terminology • Regional care-of address (RCoA): RCoA is an address obtained from the visited network via stateless address configuration mechanism. • Prefix information is learned from MAP option of the Router Advertisement message. • Only this address type is known to domains outside of MAP. • Local Binding Update: Local Binding is modified by the Binding Update message to MAP. • Once MAP receives this message, it starts DAD for RCoA because RCoA may be already occupied. • If there is no conflict, it updates Binding Cache Entry (BCE) for the binding between RCoA and LCoA of the mobile node.

14. 11.2.3 Operation • when a mobile node enters MAP domain • When a mobile node moves withinMAP domain

15. when a mobile node enters MAP domain

16. Router Advertisement and address configuration 1. When a mobile node visits a network, the node will receive Router Advertisement messages from AR(s). • When HMIPv6 is supported in the visited network, the Advertisement message will contain MAP option to allow the mobile to discover MAP address. • Available MAP list is kept in the AR and periodically sent using Router Advertisement messages. 2. Once the mobile node receives Router Advertisement messages with the MAP option which contains prefix information for RCoA, it will configure two addresses, RCoA and LCoA by the stateless address configuration mechanism. • In detail, the mobile node learns a prefix for LCoA from Prefix Information option • a prefix for RCoA from MAP option in the Router Advertisement message. • Then, the mobile node builds RCoA and LCoA by appending 64-bit prefix to 64-bit interface identifier.

17. MAP option - 11.2.5.2 Neighbor Discovery extension • MAP option is contained in the Option field of Router Advertisement messages to allow mobile nodes to learn MAP address from ARs. Figure 11-3. Router Advertisement message from access router at step 2 in Fig. 11-2.

18. Local Binding Update Figure 11-4. Exchanged messages for MAP Registration at step 4 in Fig. 11-2.

19. Local Binding Update 3. As the mobile node builds RCoA, the mobile node sends Local Binding Update message to the MAP. • The A and M flags in the Local Binding Update message should be set to differentiate from the original Binding Update message. • In the Local Binding Update message to MAP, RCoA is regarded as the home address for the mobile node and contained in the Home Address option. Mobile node's LCoA is used as the source address.

20. 4. Upon MAP receives Local Binding Update message, it binds mobile node's RCoA to its LCoA. Simultaneously, the MAP performs DAD for mobile node's RCoA. 5. The MAP will return a Binding Acknowledgement message to the mobile node, to indicate the result of the binding update to MAP. 6. The mobile node must silently discard any acknowledgement packet from MAP without Type 2 Routing Header, which contains mobile node's RCoA.

21. bidirectional tunnel • Once the binding update to the MAP is successfully completed, a bidirectional tunnel between the mobile node and MAP is established. • Any communication between the mobile node and correspondent nodes should go through the MAP. • The MAP will perform encapsulation for packets from correspondent nodes or mobile node's home agent to the mobile node • and also perform decapsulating packets from the mobile node to forward them to correspondent nodes.

22. binding update to HA and CN • Once the binding update to MAP is successfully completed, binding updates to home agent and correspondent nodes should be followed. • These binding updates are same as specified in MIPv6 standard except that RCoA is used as the care-of address. • LCoA is unknown to outside of MAP domain. • Thus, when HA and CNs sends packets to the mobile node, the Destination Address field of packet should be set to the mobile node's RCoA. • MAP intercepts them and fetches LCoA corresponding to RCoA by referring the binding cache table. • Then, it tunnels packets to the mobile node. • For the tunneling, the Destination Address field is filled with LCoA, and Source Address field is filled with the address of MAP. • Any delivered packet without Type 2 Routing Header will be discarded in the mobile node.

23. Figure 11-5. Data packet exchange between a mobile node and correspondent node at step 7 in Fig. 11-2.

24. 层次移动IPv6信令消息交互图

25. a mobile node moves withinMAP domain • If the mobile node changes its physical location within MAP domain, only binding update to MAP is required. • Thus, the old LCoA in BCE will be replaced by a new one. • Binding updates to its home agent or correspondent nodes are not necessary. • The MAP domain is determined by Router Advertisement messages from ARs. • Since binding updates to home agent and correspondent nodes are not required, the binding update latency may be significantly reduced.

26. Figure 11-6. HMIPv6 example2: when a mobile node moves into new AR within the same MAP domain.

27. Figure 11-7. HMIPv6 Example 3: when a mobile node moves into new MAP domain. Messages for home registration may not pass through MAP.

28. Hierarchical Mobile IPv6

29. Handoff Time

30. HMIPv6 • Motivation • Reduce the number of Bus when MNs move within a MAP domain • Transparency of the MN’s mobility to CNs • Location Privacy • HMIPv6 • Mobility anchor point (MAP): Local HA • MN acquires two addresses • On-link CoA: LCoA • Regional CoA: RCoA • Reduce Mobile IPv6 signaling load • Improve Handoff delay

31. Basic Operation of HMIPv6 • Extension of MIPv6 – Minor extensions to MN operation – CN and HA operation will not be affected • The introduction of the MAP concept – Minimize the latency due to handoffs between AR – Diminish signaling (including wireless resource) costs Ø MN only perform one local BU to a MAP when changing its location within the MAP domain. • Local Location Transparency • – On-Link Address : LCoA, • Regional Care-of Address : RCoA • – If the MN changes its LCoA within a local MAP domain, it only needs to register the new LCoA with the MAP. • – RCoA registered with CNs and the HA does not change. • – This makes the MN's mobility transparent to the CNs

32. HMIPv6 Operation (Home address, RCoA) HA CN Internet Home BU MAP MAP (RCoA, LCoA) MAP domain Local BU oldAR newAR MN

33. HMIPv6 Operation (Home address, RCoA) HA CN Internet MAP MAP (RCoA, LCoA’) MAP domain Local BU oldAR newAR MN

34. HMIPv6 Operation (Home address, RCoA’) HA CN Internet Home BU MAP (RCoA’, LCoA’) MAP MAP domain oldAR newAR Local BU MN

35. Basic Operation of HMIPv6

36. Basic Operation of HMIPv6

37. Basic Operation of HMIPv6

38. Basic Operation of HMIPv6

39. Dynamic MAP Discovery • n Procedure of Dynamic MAP Discovery • propagate the MAP option from the MAP to the MN through the hierarchy of routers. • The routers receiving the MAP option propagate them on certain interfaces with Router Advertisement message

40. MAP Selection in a distributed-MAPs Environment • Furthest MAP • – MN may choose to register with the furthest MAP to avoid • frequent re-registrations. • – This is particularly important for fast MNs that will perform • frequent handoffs. • Nearest MAP • – Network operators may choose a flat architecture in some cases • where a MIP handoff may be considered a rare event. • – In these scenarios, operators may choose to include the MAP • function in the lowest ARs. • – In this scenario, a MN may choose a MAP (in the AR) as an • anchor point when performing a handoff. • – This kind of dynamic hierarchy (or anchoring) is only • recommended for cases where inter-AR movement is not frequent.