greg bilodeau mike reed

DMAP-FR: Integrated Mobility and Service Management withFailure Recovery Support for Mobile IPv6 Systems

Greg BilodeauMike Reed

What is DMAP-FR?

• An extension of Dynamic Mobility Anchor Points (DMAP)

• DMAP is an extension of Hierarchical

Mobile IPv6 (HMIPv6) • HMIPv6 is an extension of Mobile

IPv6

Mobile IPv6

• Mobility in IPv6 Networks.• MIPv6 is expected to have wide

deployment in the future for all-IP mobile systems.

• More mobile apps will access multimedia and data services over IP

Mobile IPv6 - Advantages over MIPv4

• Specialized "foreign agent" routers not needed.

• Support for route optimization fundamental part of protocol.

• Packets sent to mobile node (MN) sent using IPv6 routing header rather than IP encapsulation

• Dynamic home agent (HA) discovery mechanism returns single reply to the mobile node.

Mobile IPv6 - Problems

• Does not solve local or hierarchical forms of mobility management.

• Effective mobility and service management schemes to reduce network traffic needed.

• Fault tolerance for service continuity despite network router failures.

Hierarchical MIPv6

• Allows local mobility handling.• Designed to reduce the amount of

signalling traffic between the MN and home agent (HA) and correspondent nodes (CNs).

• Utilizes local home agents called mobile anchor points (MAPs).

Hierarchical MIPv6 - MAPs

Advantages of HMIPv6 and MAPs

• Unlike FA in IPv4, MAPs not required on every subnet.

• Limit the amount of IPv6 signalling traffic outside the local domain

• Allow MNs to hide their location from CNs.

• MN may chose which MAP (or MAPs) to associate with.

Disadvantages of HMIPv6 and MAPs

• Static domain in terms of number of subnets covered.

• Single point of failure.• While mobility is addressed, service

and performance management is not considered.

Dynamic Mobile Anchor Points (DMAP)

• Integrated mobility and service management.

• MN not only determines which MAP to bind to, it determines which access router (AR) acts as a MAP.

• MAP binding based on both mobility and service requirements of the specific MN.


Location handoff: MN moves across subnet boundary Service handoff: MN moves across DMAP domain boundary MAP domain size: number of subnets in region covered by the MAP

Dynamic Mobile Anchor Points (DMAP) - The Tradeoff

Choosing a MAP "further" from the MN decreases the number of service handoffs, but increases the triangular routing overhead and location handoffs Choosing a MAP "closer" to the MN reduces the intra-subnet routing, but increases the frequency of service handoffs

Dynamic Mobile Anchor Points (DMAP) - Finding Optimal MAP

MN must be capable of collecting required statistical information.Goal is the minimization of "communication cost" per time unit.

Dynamic Mobile Anchor Points (DMAP) - Performance Evaluation


Calculating MN2DMAP: F(Mark(Xs)+1) returns the number of hops between the current subnet and the DMAP separated byMark(Xs)+1 subnets. The argument of the F(x) function is added by 1 to satisfy the initial condition that Mark(Xs) = 0 in which the DMAP has just moved into a new service area, so at the first subnet crossing event, the distance between the DMAP and the subnet is one subnet apart


Calculating NewDMAP: As MN must inform HA and all N client nodes of new RCoA


Calculating average communication overhead Includes delays between CN and DMAP, DMAP to AR of current subnet, and wireless link between AR and MN


Calculating average location change overhead


Total communication cost per time unit:

DMAP-FR

• Dynamic Mobility Anchor Points – Fault Recovery

• The addition of fault tolerance to DMAP.

Failure Recovery Design

• Assume two things:o For each Access Router there is an overlapping

coverage from other Access Routers since the failure of an AR will disconnect all Mobile Nodes attached to it

o in the case that a router(not a Mobility Anchor Point) fails or a link goes down, it can be handled by the recovery mechanism of the routing protocol.

Failure Recovery Design Cont'd

• Based on dynamically selecting an Access Router as the Mobile Anchor Point of a Mobile Node.

• It can recover from two kinds of failures:o The current Access Router can become the Mobile

Node's DMAP if the DMAP failso Access Router failure/recovery can be treated as

disconnection/reconnection. The failure of DMAP can be detected by not receiving the announcement message by timeout.


• There are Three Cases for Failure Recovery:o Failure of MN's DMAP which is not current AR.o Failure of MN's DMAP which is current AR.o Failure of MN's current AR.

Failure Modes - Failure of MN's DMAP which is not current AR

• Suppose that the MN is currently under AR2 and the current DMAP is AR1 (based on Figure 1).

• In this case, the Current AR becomes the MN's DMAP. AR2 will inform the HA and CN's that it is now the DMAP.

Failure Modes - Failure of MN's DMAP which is current AR

• The MN is under AR1 which is the current DMAP and it fails. In this case, since the wireless coverage area of the current AR is overlapping, the MN could be under radio range of several other subnets.

• The MN will register with a new AR near by which will become the new MN's DMAP. AR2 will inform the HA and CN's of the Regional Care of Address change.

Failure Modes - Failure of MN's current AR

• The MN is under AR3 when AR3 fails and the DMAP is on AR1.

• In this case the MN locates another AR, i.e. AR1, or AR2, to replace AR3. The MN will register with the new AR through a binding message.

Performance Analysis

Performance Analysis cont'd

• Using Stochastic Petri Nets because of:o their ability to deal with general time distribution for eventso their concise representation of the underlying state machine to deal

with a large number of stateso their expressiveness to reason about a MN's behavior as it migrates

from one state to another in response to events occurring in the system.

Performance Analysis cont'd

• The number of tokens accumulated in place Xs, that is, Mark(Xs), represents the number of subnets crossed by the MN since the MN entered a new service area.

• We allow it to accumulate to K (the subnet size we're trying to test), at which point we perform a service handoff.

Petri Net Explanation

• The Mobility rate at which location handoffs occur is which is the transition rate assigned to Moving.

• When a Mobile Node moves across a subnet area, a token is put in place Moves

Petri Net Explanation cont'd

• After moving into a subnet, the Mobile Node obtains a new Care Of Address, and informs the DMAP of the Care Of Address change.

• This is modeled by enabling and firing transition MN2DMAP while disabling transition Moving.

• After MN2DMAP is fired, a token in place MOVES flows to place Xs, representing that a location handoff has been completed and the DMAP has been informed of the Care of Address change of the Mobile Node.


• If the Number of tokens in place Xs has accumulated to K then it means that the Mobile Node has just moved into a new service area and a service handoff ensues.

• This is modeled by assigning an enabling function that will enable transition MovingDMAP after K tokens have been accumulated in place Xs.

• After transition MovingDMAP is fired, all K tokens are consumed and place Xs contains no tokens, representing the action that the DMAP has just moved into a new service area.

• The rate at which transition MovingDMAP fires depends on the cost of informing the Home Agent and Corresponding Nodes of the DMAP Care of Address change.


• The DMAP alternates between "work" and "Failure" states. Initially the DMAP is in the work state.

• After some time has elapsed, the DMAP goes to the failure state.

• This is modeled by transition failing. • Note that if the DMAP is already in place Failure, transition

failing cannot fire.


• While the DMAP is in failure mode, after time has elapsed representing the recovery time, the DMAP goes to the work state.

• The is modeled by the transition recovering.


• For case 1 the DMAP fails but the current AR is alive, as illustrated in Figure 1.

• In this case, the current Access Router will become DMAP, the new DMAP will inform the Home Agent and Corresponding Nodes of the Regional Care of Address change.

• This is modeled by firing transition recovering with a transition rate reflecting the cost.

• Firing this transition will flush all the tokens in place Xs as if a service handoff had happened. This is modeled by a variable input arc from place Xs to transition recovering.


• For Case2, the DMAP fails and the current Access Router happens to be the DMAP, as illustrated in Figure 1 where the MN's current AR and DMAP is AR1 and AR1 fails.

• In this case, the MN will register with a new AR near by• The new AR will become the Mobile Node's DMAP who will

then inform the Home Agent and Corresponding nodes of the new Regional Care of Address.This event is also modeled by firing transition recovering.


• For Case 3, the current AR fails but the DMAP is alive, as illustrated in Figure 1.

• In this case, the Mobile Node will register with another Access Router nearby. • The new Access Router then only needs to inform the DMAP of the Care Of

Address change. • This event can also be modeled by transition recovering.• Note that the rate to transition recovering depends on the system state which

will be characterized later.

Characterizing rate of the Recovering transition

• When transition Recovering fires, the Mobile Node will contact the DMAP. If the DMAP fails and the current Access Router is the MAP, the Mobile Node will register with a new Access router near by.

• The new access router will become the DMAP and inform the Home Agent and Corresponding Nodes of the RCoA change.

• If the DMAP fails while the current AR is still alive, the current AR will become the DMAP.

• In either case the current Access Router chosen becomes the new DMAP and the cost involved is to inform the Home Agent and Corresponding nodes.

Characterizing rate cont'd

• Since the new DMAP is F(Mark(Xs)) + hops away from the failed DMAP, the cost can be parameterized as

{ N [ F(Mark(Xs)) ] + [ F(Mark(Xs)) ] +

• The rate transition Recovering is the reciprocal of this quantity.

Overall communication costs

• A Mobile Node and its DMAP determine the service area dynamically to minimize the overall network signaling costs for mobility management, service management and fault tolerance related operations incurred by the Mobile Node. There are three costs considered:o The service costo The mobility costo The failure recovery cost

Overall communication cost

• CTotal = Cservice * + Cmobility * Crecovery * fo CTotal = overall cost incurred per time unito Cservice = average communication cost to service a

data packet.o Cmobility = average communication cost to service a

location handoff, including one that can trigger a service handoff.

o Crecovery = the communication overhead for the network to recover from DMAP or AR failures.

o Data packet rate between the Mobile Node and Corresponding node.

o f = DMAP failure rate

Average communication cost to perform failure recovery

• Ci,recovery = o F(Mark(i) + 1)

if the current AR fails while the DMAP is still aliveo F(Mark(i) + 1) F(Mark(i)

+ 1) if the DMAP fails

Cost versus K

• DMAP-FR has an optimal service area size Kopt to minimize the overall network traffic cost, when given a set of parameter values characterizing the mobility and service behaviors of the Mobile Node and failure behaviors of Access Routers in the Mobile IP networks.

Kopt versus f

• Kopt increases as f increases. • The reason is that as the failure rate increases, the Mobile

Node's DMAP likes to stay at a large service area to reduce the location handoff cost such that a location handoff will most likely only involve informing the DMAP of the location change without incurring a service handoff to migrate the DMAP.

Cost difference between HMIPv6 and DMAP-FR

• The cost difference between HMIPv6 and DMAP-FR as a function of Service-to-Mobility Ratio.

• We observe that the cost difference between HMIPv6 and DMAP-FR degenerates,then sharply rises as SMR continues to increase.

• We conclude that DMAP-FR performs better than HMIPv6, especially when SMR is high.

Conclusion

• DMAP-FR - efficient mobility and service management with failure recovery supporting Mobile IPv6 environments.

• Devised a computational procedure to compute the optimal service area size that would minimize the overall network traffic cost.

• Compare our scheme with HMIPv6 • Performance gain due to a proper selection of the best

service area dynamically.

References

• W. He and I.R. Chen, "DMAP-FR: Integrated Mobility and Service Management with Failure Recovery Support for Mobile IPv6 Systems," 6th IEEE International Conference on Information Technology: New Generation, Las Vegas, April 2009.

• I. R. Chen, W. He, and B. Gu. DMAP: A scalable and efficient integrated mobility and service management scheme for Mobile IPv6 systems. Wireless Personal Communications, 43(2):711–723, 2007.

• R. Ghosh and G. Varghese. Fault-tolerant Mobile IP. Technical Report WUCS-98-11, Washington University, 1998.

• D. Johnson, C. Perkins, and J. Arkko. Mobility Support in IPv6. http://www.ietf.org/rfc/rfc3775.txt, IETF, Work in Progress, 2004.

• H. Omar, T. Saadawi, and M. Lee. Supporting reduced location management overhead and fault tolerance in Mobile-IP systems. In IEEE International Symposium on Computers and Communications, pages 347 – 353, 1999.

• H. Soliman, C. Castelluccia, K. El-Malki, and L. Bellier. Hierarchical Mobile IPv6 mobility management. http://www.ietf.org/rfc/rfc4140.txt, IETF, RFC, 2005.

• T. You, S. Pack, and Y. Choi. Robust hierarchical Mobile IPv6 (RH-MIPv6): an enhancement for survivability and fault-tolerance in Mobile IP systems. In IEEE 58th Vehicular Technology Conference, pages 2014–2018, 2003.

• 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.

http://people.cs.vt.edu/~irchen/5214/pdf/itng09.pdf

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greg bilodeau mike reed

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