View
213
Download
0
Category
Tags:
Preview:
Citation preview
1
A Dynamical Redirection Approach to Enhancing
Mobile IP with Fault Tolerance in Cellular Systems
Jenn-Wei Lin, Jichiang Tsai , and Chin-Yu Huang
IEEE Global Telecommunication Conference 2002Taipei, Taiwan, R.O.C., Nov. 17-21, 2002
Department of Computer Science & Information Engineering, Fun Jen Catholic University, Taipei, Taiwan
jwlin@csie.fju.edu.tw
3
Introduction
Mobility IP in Cellular Systems– Ongoing data sessions without disruption due to
mobility
– IETF RFC 2002• Two kinds of mobility agents
– Foreign agent (FA)
– Home agent (HA)
– Failure Occurrence• Interrupting the data executable capability of mobile users
4
Introduction
Mobile Packet Data Flow – Data request
Radio Access Network
Mobile Mobile Packet Packet BaBackboneckbone
Foreign Agent Home Agent
Internet
Application Server
Mobile Node
5
Introduction
Mobile Packet Data Flow – Data response
Home Agent
Internet
Application Server
Mobile Mobile Packet Packet BaBackboneckbone
Foreign AgentRadio Access Network
Mobile Node
6
Introduction
Failure Occurrence – Failures in FAs
• Data requests unable to be delivered
Home AgentForeign Agent
Internet
Application Server
Failure
Radio Access Network
Mobile Node
Mobile Mobile Packet Packet BaBackboneckbone
7
Introduction
Failure Occurrence– Failures in HAs
• Data response unable to be sent back
Home AgentForeign Agent
Internet
Application Server
Failure
Radio Access Network
Mobile Node
Mobile Mobile Packet Packet BaBackboneckbone
8
Introduction
Goal– Not terminating the data services of mobile
users when failures occur in mobility agents• Proposing a reliable Mobile IP protocol in cellular
systems– Tolerating multiple failures of mobility agents
– Not needing the hardware support
10
Background
Wireless Network Model
RAN FA
FA
FA
Interconnection Network
MN
MN
RAN
RAN
Wireless IPBackbone
Router
Router
Router
Router
Router
Router
HA
HA
Internet
RAN: Radio Access NetworkFA: Foreign AgentHA: Home Agent
11
Background
Previous Approaches– R. Ghosh and G. Varghese [1998]– J. H Ahn and C. S. Hwang [2001]– Features
• Mobility agent– Hardware replication
• Mobility information– Potential long registration delay– Stable storage
• Fault-tolerant range– Within a network segment
13
Proposed Approach
Basic Idea– Workload redirection
• Network-initiated handoff– Redirecting the workload of the faulty FA to other failur
e-free FAs
• Tunneling – Redirecting the workloads of the faulty HA to other failu
re-free HAs
14
Proposed Approach
Network-Initiated Handoff– Modifying the FA selection algorithm
• Relationship between RANs and FAs before a FA failure
FA
.
.
.
RAN
RAN
RAN
FA
FAInterconnection
Network
.
.
.
MN
MN
15
Proposed Approach
Network-Initiated Handoff – Resetting the FA selection algorithm (Cont.)
• Relationship between RANs and FAs after a FA failure
Virtually moving the locations of MNs under the coverage area of the faulty FA
Faulty FA
.
.
.
RAN
RAN
RAN
Failure-free FA
Failure-free FAInterconnection
Network
.
.
.
MN
MN
: Original deliverypath
: Possibly fault-tolerantdelivery path
16
Proposed Approach
Tunneling– Performing the tunneling on the neighbor route
rs
Wireless IPBackbone
HA
Internet
Router Router
Network Segment
17
Proposed Approach
Tunneling– Intercepting the response packets by failure-fre
e HAs
Server
Wireless IPBackbone
Faulty HA
FA
Failure-free HA
Router
Tunneling
Tunneling
MNRAN
: Original delivery path : Fault-tolerant delivery path
Internet
Tunneling
18
Proposed Approach
Reconstructing mobility information– Sending a mobility-reconstruction message to e
ach FA– Filtering the visitor list to find the MNs original
ly managed by the faulty HA– Re-organizing each selected visitor entry as the
form of a mobility binding entry
20
Evaluation
Performance Degradation on a Failure-Free Mobility Agent– Probability of blocking packet data in a failure-free mo
bility agent
– Packet data to a mobility agent • Poisson distribution
– Processing time of packet data in a mobility agent• Arbitrary distribution
– M/G/c/c queuing model
21
Evaluation
Blocking Probability of a Failure-Free Mobility Agent– Erlang’s loss formula given from the M/G/c/c queuing
model
c
i
i
k
c
k
Blocking
i
Fw
c
Fw
P
0 !
!
22
Evaluation
Traffic Parameters
Parameter Meaning Value
F Number of faulty mobility agents 1
c Number of resource units in a mobility agent
50 (100)
λ Arrival rate of data to a mobility agent
10, 25, 50, 100
μ Service rate of data in a mobility agent
1
wk Ratio for redirecting the workload of the faulty mobility agent to the failure-free mobility agent k
0.1 to 1.0
25
Evaluation
Blocking Probability– When is not too large (e.g. 10 in FA and
10, 25 in HA), the blocking probability nearly approaches 0 regardless of the variance of wk.
– When is very large (e.g. 100), the blocking probability may be not large for the smaller wk.
– Four used traffic intensities are larger than the general traffic intensity in a commercial wireless system
27
Conclusions
A New Approach to Tolerating Multiple Failures of Mobility Agents– Not incurring failure-free overhead– Not requiring hardware support– Dynamically generating the backups of faulty mobility
agents Overhead
– Performance degradation on a failure-free mobility agent
– M/G/c/c queuing model (Erlang’s loss formula)
28
Conclusions
Comparisons
ComparingMetrics
ProposedApproach
Approach in Ghosh and Var
ghese [1998]
Approachin Ahn and Hwa
ng [2001]
Hardware support
No Yes Yes
RangeWhole system
networkIn a network
segmentIn a network
segment
Failure-free overhead
NoPotential long
registration
Message logging and checkpointin
g
Failure overhead
Network-initiated Handoff
TunnelingSearching
ARP executionARP execution
Restoration
Recommended