Design and Analysis of Optimal Multi-Level Hierarchical Mobile IPv6 Networks
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Transcript of Design and Analysis of Optimal Multi-Level Hierarchical Mobile IPv6 Networks
Design and Analysis of Optimal Multi-Level Hierarchical Mobile IPv6 Networks
Amrinder SinghDept. of Computer Science
Virginia Tech.
Agenda Introduction OM-HMIPv6 Analytical Modeling Numerical Results Simulation Validation Conclusion
Introduction Mobility management is essential for keeping
track of user’s current location
Many schemes proposed for cellular networks
Next-generation wireless/mobile network will be unified networks based on IP technology
Design of IP-based mobility management schemes has become necessary
Introduction HMIPv6 is enhanced version of Mobile IPv6
Minimizes signaling cost using a local agent called mobility anchor point (MAP)
MN entering MAP domain receives Router Advertisement (RA) from one or more local MAPs
MN can bind current CoA with an address on MAP’s subnet
Communication of MN MAP receives all packets on behalf of MN
Encapsulates and forwards directly to MN’s current address
Movement of MN within local MAP domain requires registration of new CoA with MAP reducing location update
To reduce location update further, the case of multi-level hierarchical MAPs
Background One of the earlier schemes focused on
determination of optimal size of regional network
Did not focus on determining optimal hierarchy
Other schemes proposed to optimize HMIPv6 did not consider the case of multi-level hierarchical structure
Optimal Multi-Level HMIPv6 Multiple MAPs organized in a tree structure
Root MAP Intermediate MAP Leaf MAP
Better fault tolerance, failure of MAP affects only the sub-tree under the MAP
Reduction in location update cost by localization of binding update procedure
Increase in packet delivery cost due to encapsulation and decapsulation
Binding Update MN sends Binding Update (BU) message to RMAP
At LMAP, check if MN is already registered with it If it is, registration completed Otherwise register and forward the BU
At each IMAP, check for registration as with LMAP
Process stops at IMAP where MN is already registered
Parameters for determining optimal level The number of MNs
Calculate the average number of MNs in network and divide by total area to determine density
MN mobility Determine average MN velocity during time interval
T
MN activity Determine session arrival rate and average session
size during T
Configuration of OM-HMIPv6 RMAP broadcasts RA with DIST=0
IMAP receives RA and re-broadcasts RA after increasing DIST field and compares DIST with optimal depth D*
If DIST<D*, MAP appends its IP address to MAP hierarchy list
Otherwise, forward RA as it is
Can employ some kind of loop elimination
Adaptation Scheme Parameters defined change from time to time
Need to redefine optimal hierarchy
Recalculate optimal hierarchy and perform reconfiguration
Not done very often
Analytical Modeling
Assumptions Access Routers (AR) are uniformly distributed
in each LMAP
The tree formed is a binary tree
Fluid-Flow mobility model with rectangular cell configuration
Rectangular cell configuration
Location update cost Number of cells in network = N, i.e. ARs
Number of ARs located in k-level MAP domain
Lc is the perimeter if cell
Lk is perimeter of k-level MAP domain
Location Update Cost Crossing rate for fluid flow model is given by
Total location update cost takes into account all possible crossings in the network
MNs moving in from foreign networks MNs moving across k-level MAP domains MNs moving across AR cell boundaries
ρ is the density of MNsv is the average velocity of MNs
Location Update CostUpdate Cost to HA caused by MN moving to foreign network
Sum of location update incurred by crossing k-level MAP domain area
Location cost incurred by crossing from one cell to another
Unit Location update cost
ω and η are unit update cost over wired and wireless link respectively
where H is distance between RMAP and AR and di-1,i =1
Packet Delivery Cost Need to consider transmission cost and processing
cost at each entity Packet delivery from CN to RMAP is given by
α is the unit transmission cost over a wired linkPHA is processing cost at HA
Packet Delivery Cost Packet delivery cost from RMAP to AR
Packet Delivery cost from AR to MN where β is unit transmission cost over wireless link
Calculation of Processing cost PMAP(k) is processing cost at k-level MAP domain
Includes lookup cost and packet encapsulation/decapsulation cost
PMAP(k) is assumed to be proportional to log(NU(k))
Calculating optimal hierarchy Formulate total cost as a function of
hierarchy and SMR
SMR is session arrival rate divided by mobility rate
Then define the difference function
Calculating optimal hierarchy If is larger than 0, the optimal hierarchy is 0
Otherwise optimal hierarchy is given by
Optimization can also application based Calculate total costs independently for each application Calculate weighted total cost
Numerical Results System Parameters used
Numerical Results
Optimal Hierarchy increases with number of ARs. More importantly an optimal hierarchy level exists
Session Arrival rate is normalized to 1As SMR , mobility and location cost As ARs , more levels and location cost
Numerical Results
Higher SMR means that packet delivery cost dominates the total cost and a lower hierarchy will reduce the total cost. Adaptive scheme will be effective
Varying the communication costs does change optimal hierarchy by determining which cost dominates.
Simulation Validation 5 types of MAP hierarchy evaluated. Use random walk mobility model
Routing probability for each direction is the same
Simulation Validation The MN stays in a given cell
area for time tR
This follows Gamma distribution with b=kλm
The session arrival process follows Poisson distribution
The session length is modeled by Pareto distribution with mean =ak/(a-1)
Simulation ResultMean session length is set to 10. Session arrival rate is normalized to 1.As SMR , mobility , hence frequency of binding updates Higher hierarchy implies lower binding cost as more number of LMAPs and IMAPs means binding update does not reach RMAP often
Simulation ResultMobility rate is fixed at 0.001We need to count how many MAP processings occur when packets are deliveredAs SMR , session arrival rate More packets to deliverAlso cost greater for higher hierarchy
Simulation ResultTotal cost is the sum of binding update and packet delivery costsValidates the analytical result that lower SMR means more hierarchical levels while a higher SMR means lower hierarchical levels
Conclusions Authors provide extensive analysis on multi-
level HMIPv6 which can support scalable services
Showed that optimal hierarchical level exists for the network
Investigated the effect of SMR on hierarchy However, did not talk about how often
reconfiguration would be needed and did not indicate the cost that would incur.