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Slide 1
MANETconf: Configuration of
Hosts in a Mobile Ad Hoc Network
Authors: Sanket Nesargi & Ravi Prakash
Originally Published: IEEE INFOCOM
’02, New York, June 2002
Presented By: Reed Newman
Date: Oct 3rd, 2007
Slide 2
Outline
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Background Information
Topic Primer
System Model
Related / Previous Work
MANETconf Concept
MANETconf Operation
Making MANETconf Robust
Security Issues
Simulations
Conclusions
Slide 3
Background Information

Sanket Nesargi
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Received M.S. and Ph.D. in CS at University of Texas at Dallas
Worked at Nortel for a few years
– Researches:
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Mobile Computing/Wireless Networks
– Network Service Protocols
– Protocol Design Frameworks
– Security
Transport/Network Layers in Fixed and Wireless Networks
Group Communication
Sensor Networks
Peer-to-Peer Systems
Bioinformatics
– Personals:
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Moving from “Hair Metal” into Pink Floyd, Led Zeppelin, Rainbow, Deep Purple
Rides a Kawasaki Ninja ZX 6 motorcycle
Loves his BMW 323i
Plays Squash, Badminton, Cricket
His website at UTD is called “The Dark Dungeon”
Slide 4
Background Information

Ravi Prakash
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Received Ph.D. in CS at The Ohio State
University in 1996
– Researches:
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Mobile Computing
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Location Management
Mobile-TCP
Cell Planning
Channel Allocation
• Checkpointing and Recovery
• Causally and Totally Ordered
Message Delivery
• Clocks and Dependency Tracking
– Personals:
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Nesargi’s Advisor
Big Robert De Niro fan
Toastmaster International Member
He “comes in peace and wants to
make the world a happy place.”
Slide 5
MANETs: Primer
 Typical
Wireless
Networks:
– Wireless Server
Assigns DHCP,
IP,DNS, netmask
– Data is routed
through server
– Wireless Server may
be Internet gateway
Laptop computer
Laptop computer
IBM Compatible
Wireless Server
Laptop computer
Laptop computer
Laptop computer
Slide 6
MANETs: Primer
 MANET
(Mobile
Ad Hoc Network):
Laptop computer
– Group of mobile,
wireless nodes
working
cooperatively and
spontaneously
– Devoid of fixed
infrastructure or
central
administration
Laptop computer
Laptop computer
Laptop computer
IBM Compatible
Laptop computer
Slide 7
System Model
Without centralized servers, unconfigured
nodes joining the MANET must be assigned
a unique IP addresses.
 Hosts already in the MANET must be
responsible for uniquely configuring hosts
wishing to join the MANET.
 Hosts in the MANET must be responsible for
allowing graceful and abrupt host departures.

Slide 8
System Model

In IPv4, the MANET can
use:
– 10.0.0.0 – 10.255.255.255
– 172.16.0.0 – 172.31.255.255
– 192.168.0.0 – 192.168.255.255
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
Laptop computer
Nodes communicate
through the exchange of IP
packets.
Hosts of edges of MANET
may not be directly
reachable. MANET nodes
must behave as routers and
forward packets from the
source to the destination.
Laptop computer
Laptop computer
Laptop computer
IBM Compatible
Laptop computer
Slide 9
Related/Previous Work

Zeroconf Working Group:

Assigns unique IPs to nodes in:

Limits the flexibility of Ad Hoc Networks
– Attacks similar problem of network configuration
with the lack of dedicated servers.
– Single network segments where all nodes can
directly communicate.
– Multiple segments connected to the same router.
Slide 10
Related/Previous Work

PMWRS (Perkins, Malinen, Wakikawa, Royer, Sun):
– Similar to Zeroconf.
– Performs duplicate address detection through multiple rounds of MANETwide flooding.
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PMWRS Limitations:
– Uses AREQ and AREP.
– Tied to underlying routing protocol as it specifies the routes to be used by its
messages.
– Uses 169.254.*.* IP block. Routers drop packets! This limits hosts ability to
route packets after configured.
– Network selects a candidate IP for the host joining the network. Checks for
conflicts by polling hosts in the network. Timeout delays and retry constants
are limiting when the size/shape of network is unknown.
– If multiple hosts request an IP concurrently, PMWRS may assign two hosts
the same IP.
– Much of the 169.254.*.* address block is reserved by IETF for future use.
Slide 11
Related/Previous Work

Hardware Based Addressing:
– Use the “unique” hardware address of a card to help uniquely assign
IPs (MAC address in Ethernet Adapters).

Hardware Based Addressing Limitations:
– MANET nodes not restricted to NICs with unique MAC addresses.
– Not all NICs have unique addresses.
– Some devices allow for the reprogramming of the MAC address.
– Nodes can be easily determined by tracking the MAC. Security?
Slide 12
MANETconf Concept

Assign unique IP addresses to hosts despite dynamic
topology by employing a mutual exclusion algorithm.
– A node proposes an IP address for an incoming host.
– If proposed IP is accepted by all other hosts, the incoming host is
assigned that IP.

Proposed solution is a modified version of the RicartAgrawala algorithm.
– RA Algorithm modification include the ability to be flexible to
changing network topology and a changing number of users in the
network.
– RAs inflexibility for topology changes is the motivation for
MANETconf.
Slide 13
MANETconf Operation

MANET Initialization:
– Requestor broadcasts its
Neighbor_Query message
and starts its
Neighbor_reply_timer.
– Very first requestor will not
receive any replied.
– When timer expires, the
requestor will try again and if
there is still no response it
assumes it is the first node in
the MANET.
Node j
Slide 14
MANETconf Operation

New Node Joining the MANET:
– Node i wishes to join the network.
Node j is currently the only node in
the network.
– i broadcasts the Neighbor_Query
message.
– j responds before the timer expires.
– i selects j as its initiator and ignores
any other Neighbor_Replies it may
receive.
– i sends j a Requester_Request
message.
Node j
Node i
Slide 15
MANETconf Operation

New Node Joining the MANET (cont’d):
– j polls other nodes in the network asking if IP
x is available for use. Other nodes check
their Allocated IP and Allocated_pending
lists.
– If all responses to j are affirmative, j:
• Assigns IP x to node i.
• Adds IP x to its Allocated IP list.
• Floods this information throughout the
MANET so other hosts can also transfer IP x
to their Allocated IP lists.
– If at least one host responses with a
negative, the entire process is repeated with
a new IP (x’).
– Process is repeated until node i is assigned
an IP or the initiator_request_retry number is
exceeded. j then notifies i with a failure
message stating that no resources are
available.
Node j
Node i
Slide 16
MANETconf Operation

Concurrent Address Initiation:
Node a
Node b
– Nodes a and e wishes to
concurrently join the network.
– If the two initiators (b and d) chose
unique IPs for a and e, there is no
conflict.
Node c
– If initiators b and d happen to chose
the same IP for a and e, the
initiators IP will be used to set
priority. The higher priority initiator
will receive the affirmative ack and
the lower priority initiator will
receive the negative ack.
Node d
Node f
Node e
Slide 17
MANETconf Operation

Graceful Departure of
Node:
– Node i wishes to depart the
network and relinquish its IP
before leaving the network.
– i broadcasts the
Address_Cleanup message.
– All nodes in the network
remove the used IP from their
Allocated IP list.
Node j
Node i
Slide 18
Making MANETconf Robust

Abrupt or Ungraceful Node Departure:
– Node a crashes or ungracefully leaves the
network.
Node a
Node b
– Node e wishes to join the network. It selects
node d as its initiator.
– During node d’s initialization process, it
sends Initiator_Request messages to all the
IPs in its Allocated IP list.
Node c
– Node a will fail to respond to the
Initiator_Request message.
– Node d then sends an individual
Initiator_Request message to just node a.
Node d will wait until its request_reply_timer
expires again. It will retry again based on
the threshold set by request_reply_retry.
Node d
– With no response from node a, node d
sends an Address_Cleanup message
throughout the MANET to release node A’s
IP.
Node f
Node e
Slide 19
MANETconf Operation

Requestor Migration:
– Node a wishes to join the network.
It selects b as its initiator.
Node a
– Node a migrates and is unable to
communicate with b. Node a now
chooses c as its initiator.
Node b
Node c
Node d
– Node a informs c of its previous
attempt to request an IP from b.
Node b
– Node c sends node b a message
informing b of node a’s migration.
– Node b still queries for an IP for
node a. When node b arrives at a
valid IP for node a, the result is
sent to node c and node c initiates
node a.
Node a
Node c
Node d
Slide 20
Making MANETconf Robust

Initiator Crash:
Node a
Node b
– Node a wishes to join the network.
It selects b as its initiator.
– In the middle of the configuration
process, node b crashes.
– Eventually node a’s
Address_allocation_timer will
timeout. Node a will then perform
another Neighbor_query and select
a new initiator if one can be
reached.
– Any other nodes that reserved an
IP from node b’s address request
will eventually time out and the IP
will be flushed from the
Allocated_Pending lists.
Node c
Node d
Node f
Node e
Slide 21
Making MANETconf Robust

Network Splits:
Node a
Node b
– The link between nodes c and d
fails. The network splits into two
networks.
– All nodes in one partition can
assume that the nodes in the other
partition have departed
ungracefully and cleaned up
accordingly.
Node c
Node d
Node f
Node e
Slide 22
Making MANETconf Robust

Partition Detection:
– During a network split, what prevents an
entering node on one partition from
assuming the IP of a node on a second
partition?
Node a
Node b
– Partitions keep two identifiers – lowest
partition IP address and UUID.
– One partition has the node with the lowest
IP address. Nodes in this parent partition
clean up the addresses from the second
partition.
– Clean up is also performed in the second
partition if a node requests an IP address.
As the lowest IP in the parent node are
unobtainable, nodes in the second partition
determine what IP address is the lowest
number. This lowest IP address node then
floods the partition and all nodes in that
partition then know which node is the
partition identifier.
Node c
Node d
Node f
Node e
Slide 23
Making MANETconf Robust

Partition Detection (cont’d):
Node a
– If no IP address assignment
is initiated on the second
partition, a clean up is never
triggered and the split is not
detected.
– In this case, if the lowest IP in
tables become unreachable
after a number of retries a
cleanup can be initiated.
Node b
Node c
Node d
– Methods work even if
network is partitioned into
multiple partitions.
Node f
Node e
Slide 24
Security Issues

Susceptible to DOS attacks
– A rogue node could act as an initiator and effectively allocate all free IPs to
phantom nodes and prevent valid nodes from joining the network.
– The rogue node can also respond to requests on behalf of the phantoms to
prevent clean ups.

Susceptible to Malicious Clean up Messages
– A rogue node could clean up the IPs of valid nodes and disconnect them
from the network. If this happens to an initiator, duplicate IPs could exist.

Authors claim that their proposed solution is only as insecure as other
solutions and protocols such as ARP and RARP.

Resolution to the above attacks can be achieved with the use of digital
certificates from a trusted Authentication Server.
Slide 25
Simulations

Performed on ns-2 (ver2.1b6a) with CMU
extensions to support ad hoc networks.
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Simulations for related approaches (Zeroconf, etc)
are not performed due to their “deterministic latency
and number of messages that can be computed
theoretically.”

Simulations do not implement support for handling
partitioning.
Slide 26
Simulations

MANET is modelled with moving nodes. Nodes pick a random coordinate, move at a
speed of 5 m/s, stop at the destination for 10s, then repeat the process.
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Maximum number of nodes is 40, 50, 60, and 80.
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Maximum node density is one node per 0.02km2.
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For 40, 60, and 80 node simulations, simulations are started with 25, 35, and 45 preconfigured nodes respectively.
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Node arrival times uniformly distributed in the range 0 – 70s.
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Node lifetime varies between 0-1000s, 0-2000s, and 0-15000s.
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Graceful departures varied between 75% and 100%.
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Underlying routing protocol is DSDV.
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No arrivals accepted in the first 200s to allow nodes to set up routing tables.
Slide 27
Simulations

75% graceful and 25% abrupt
departures.
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Most addresses are allocated in
under 0.5s

5s allocation attempts correspond to
unanswered initiator requests and
are consistent with the numbers set
in the initiator_request_timer field.

10s allocation attempts correspond
to situations where abrupt departure
nodes were cleaned up.
Slide 28
Simulations
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100% graceful departures.
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Latency is high for some
address allocation attempts
due to packet loss.
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Only the results of the
samples that are not dropped
are shown.

Time required for address
allocation increases with the
number of nodes in the
network.
Slide 29
Simulations

Broadcast:
– Initiator_Request
– Address_Cleanup
– Other Flood Messages

Multicast:
– Messages sent to nodes that fail
to respond to Initiator_Request
messages.

Unicast:
– All communications directed
back to the initiator.
Slide 30
Conclusions

MANETconf allows for dynamic allocation of
IPs in a Mobile Ad Hoc Network without the
need for a centralized server running DHCP.

Proposed solution is tolerant to splits and
merges and can tolerate message loss.

Reasonable overhead.
Slide 31
Questions?