Shall we apply paging technologies to proxy mobile IPv6? J.-H. Lee, T.-M. Chung, S. Pack, and S. Gundavelli 1 in Proceedings of the 3rd international workshop on Mobility in the evolving internet architecture, Seattle, WA, USA, 2008, pp

Outline Introduction Preliminaries – Proxy Mobile IPv6 – Paging Mechanism Paging Extension for PMIPv6 Performance Evaluation Conclusions and Future Work 2

Introduction The Host-Based Mobility protocol depends on the mobility stack installed in a mobile host (MH). – which typically operates in a limited capacity maintaining binding information has a strong influence on the limited resource. Proxy Mobile IPv6 (PMIPv6) supports network-based mobility for the MH. – the MH does not need to install the mobility stack into its protocol stack. handoff across different networks without its own mobility signaling cost 3

Introduction (cont.) Drawbacks of PMIPv6 – all mobility signaling is controlled through the mobility entities – data traffic of MH must be managed by the mobility entities – This network-based mobility architecture not only lacks the network resource, but also limits the scalability in support of very large numbers of MHs we propose a paging extension scheme – to minimize the signaling overhead and optimize mobility management cost in PMIPv6. 4

Outline Introduction Preliminaries – Proxy Mobile IPv6 – Paging Mechanism Paging Extension for PMIPv6 Performance Evaluation Conclusions and Future Work 5

Proxy Mobile IPv6 (PMIPv6) Mobile IPv6 requires client functionality in the IPv6 stack of a mobile node. – Host-based Network-based mobility is another approach to solving the IP mobility challenge. Per-MN-Prefix model – an addressing model where there is a unique network prefix or prefixes assigned for each node. 6 S. Gundavelli, K. Leung, V. Devarapalli, K. Chowdhury, and B. Patil, "Proxy Mobile IPv6," IETF, RFC 5213, 2008.

Local Mobility Anchor (LMA) – has the functional capabilities of a MIPv6 home agent as with the additional capabilities – the topological anchor point for the MN’s “home network” prefix(es) in a PMIPv6 domain Mobile Access Gateway (MAG) – a function on an access router – tracks the MN’s movements – manages the mobility signaling on behalf of an MN 7

8 home domain wide area network correspondent node MAG2 MAG1 AP1 AP2 Initiation LMA home domain (e.g., 1400:0112::0/40) 1 L2 access authentication with MN-ID 2 Proxy Binding Update: with MN-ID and the address of MAG1 (e.g., proxy-CoA1) 3 Proxy Binding Ack.: with a home prefix for the MN (e.g., 1400:0112::1/64 ) 4 1) Unicast Router Advertisement 2) Configure “home address” (e.g., 1400:0112::1::30)

9 home domain wide area network correspondent node MAG2 MAG1 AP1 AP2 LMA home domain (e.g., 1400:0112::0/40) Communication Communicate with the MN using the MN’s “home address” (1400:0112::1::30::MN_MAC) Downlink : LMA tunnels packets that destined to the MN’s “home address” to Proxy-CoA1 Uplink: MAG1 tunnels packets from the MN to the LMA data packets

10 home domain wide area network correspondent node MAG2 MAG1 AP1 AP2 Handover within the Home Domain LMA home domain (e.g., 1400:0112::0/40) 1 L2 access authentication 2 Proxy Binding Update: with MN-ID and the address of MAG2 (e.g., proxy-CoA2) 3 Proxy Binding Ack.: with the same home prefix for the MN (i.e., 1400:0112::1/64 ) 4 1) Unicast Router Advertisement 2) use the same “home address” (e.g., 1400:0112::1::30) data packets

11 home domain wide area network correspondent node MAG2 MAG1 AP1 AP2 LMA home domain (e.g., 1400:0112::0/40) Communication-2 Communicate with the MN using the MN’s “home address” (1400:0112::1::30::MN_MAC)

Network traffic bottleneck at the LMA while it tries to support a large number of MHs – all registration messages generated by MAGs, – data traffic generated by MHs, and – data traffic destined for MHs 12

Paging Mechanism operates on a set of neighboring networks which constitutes a paging area. – active mode the mobility entity, i.e., home agent or LMA recognizes the exact location of the MH – idle mode the MH hands off across different networks in a paging area without the registration procedure resulting in need for paging achieve a reduction in signaling loads occurred by MHs in the idle mode a battery consumption at the MH is reduced significantly 13

paging mechanisms for Mobile IPv4 in [3] Home Agent paging – the paging initiator is the home agent – simple  required only at the home agent and mobile host – flexible  different update and paging algorithms may be implemented in the home agent and mobile hosts. – reduced efficiency  home agents may be located some distance from the mobile hosts – poor scalability – decreasing reliability  the failure of a home agent or paging process in a home agent would render all the mobile hosts it serves unreachable – deployment  the paging information could be considered confidential and may not be available 14 [3] R. Ramjee et al. IP Paging Service for Mobile Hosts. In Proc. of ACM SIGMOBILE, pages 332–345, July 2001.

Foreign Agent paging – the previous foreign agent is the paging initiator – simple  requiring changes to foreign agents and mobile hosts. – scalability  the processing load of paging is distributed among the different foreign agents – efficient and deployable  the confidentiality issues of Home Agent paging are avoided – somewhat flexible  different update and paging algorithms can be implemented in the mobile hosts and foreign agents – will not work with the mobile host co-located CoA option of Mobile IP – reliability  the failure of the previous foreign agent could result in the mobile host being unreachable indefinitely 15

Domain paging – paging initiator selected dynamically – load balancing for performance – fail-over for reliability – reliability  a completely distributed approach, retaining the scalability and efficiency – confidentiality issues of Home Agent paging are avoided – truly localized  no updates to the home agent due to paging – works both with the co-located care-of option of Mobile IP as well as the network-based foreign agent option. – additional functionality in the routers – not as simple to implement nor as easy to deploy 16

paging performance study [6] the paging size is the most important unit for acquiring the effect of IP paging. IP paging shows its ability only when the number of cells per network is small. However, we argue that this interpretation of paging in IP-based mobility protocols has to be examined under various performance parameters, not only by the cell size. 17 [6] J. Kempf and P. Mutaf. IP Paging Considered Unnecessary: Mobile IPv6 and IP Paging for Dormant Mode Location Update in Macrocellular and Hotspot Networks. In Proc. of IEEE WCNC, pages 1032–1036, March 2003.

Outline Introduction Preliminaries Paging Extension for PMIPv6 Performance Evaluation Conclusions and Future Work 18

Design considerations Support for unmodified mobile hosts – the previous paging mechanisms proposed for HBM protocols require paging response messages sent from the MH Reduction in mobility signaling cost – signaling converging to the LMA increases the network unavailability probability decreases the scalability in support of very large numbers of MHs Avoidance of paging processing at a single point – the paging processing would be distributed among the MAGs 19

Paging Architecture the MAGs in the same paging area are involved in the same multicast group time-based state – a lifetime of a currently active binding for an MH turns into the idle mode when the lifetime is expired – the serving MAG informs other MAGs located in the same paging area The paging area information is only updated in the LMA when the MH hands off to a new paging area 20

Paging Message Sequence 21 Idle Indication?

Outline Introduction Preliminaries Paging Extension for PMIPv6 Performance Evaluation Conclusions and Future Work 22

Network Model each paging area is consisted of the same number of cells an MAG is located in each cell – a cell is considered as a subnet The number of cells in the L-level paging area is calculated as follows 23

Mobility Model Fluid-flow model – suitable for MHs having a high mobility and static velocity The direction of an MH is distributed uniformly in the range of (0, 2π) The cell and paging area crossing rate: – ν  the average velocity of the MH – ρ  the MH’s density – Lc  the cell perimeter – Lp  the paging area perimeter 24

Cost Analysis the location update for the basic PMIPv6 25 MH-MAG MAG-LMA tunnelMove out of cell location update refreshing

the location update for the PMIPv6 with paging extension 26 tunnel active mode MH 移出 cell location update refreshing incoming/outgoing session for idle mode MH Signaling between MAGs MH-MAG MAG-LMA paging when session incoming

Numerical Results it is typically assumed that the distance between the MAG and the LMA (t γ ) is larger than the distance between the MAGs (t β ) p α includes CPU processing time, queuing delay, etc 27 [11] X. Zhang, J. Castellanos, and A. Campbell. P-MIP: Paging Extensions for Mobile IP. ACM Mobile Networks and Applications, 7(2):127–141, March 2002 Size of a cell = 6500 m 2  32~130 MHs per cell

slow moving MHs stay in the same cell (subnet) for longer periods than the fast moving MHs. the size of paging areas is carefully designed and deployed in networks. such a problem can be absorbed by applying the dynamic paging algorithm [10] – the paging area is dynamically allocated based on several performance units 28 [10] Xie, H., Tabbane, S. and Goodman, D.J. Dynamic Location Area Management and Performance Analysis. In Proc. of IEEE VTC, pages 536–539, May 1993.

the fast moving MHs frequently hand off across the cell boundary 29

small percentage of MHs operating in the active mode 30

if there are all MHs operating in the active mode, the paging extension scheme cannot improve the network performance 31

Outline Introduction Preliminaries Paging Extension for PMIPv6 Performance Evaluation Conclusions and Future Work 32

Conclusions PMIPv6 follows a centralized mobility management architecture – poses heavy burden on the LMA and – causes network traffic bottleneck at the LMA. The proposed paging scheme has a decentralized paging architecture that distributes the paging state among the MAGs – the processing load of paging MHs is decentralized. We have modeled the location update cost – using layered hexagonal network model and the fluid flow model. numerical results confirm that the proposed paging extension scheme provides significant reduction in the location update cost In future, we would like to explore dynamic paging algorithms to further reduce the signaling load. 33