Transcript Address Configuration in Adhoc Networks in IPv4, by Meenakshi

Address Configuration in
Adhoc Networks in IPv4.
By
Meenakshi Sundaram V
Problem Definition
 In a MANET, group of nodes dynamically form a
network.
 No dedicated machine providing DHCP services.
 Providing an efficient addressing scheme for an
infrastructure less network (adhoc).
 Existing adhoc literature bypass node
configuration, assume nodes are configured
prior.
DHCP
DHCP
 Network admin. assigns a range of IP addresses
to DHCP
 client computer on the LAN has its TCP/IP
software configured to request an IP address
from the DHCP server when that client
computer's network interface card starts up
 Request and grant process uses a lease
concept.
 Dynamic reuse of IP address.
DHCP in ADHOC domain
Centralized administration is an impossible
task.
Automated Dynamic assignment of IP
address a desirable goal.
Resolution of addresses when two or more
partitions merge.
Characteristics for IP address protocol
 IP address valid only for the duration for
for which node stays in network.
 Node departs, IP address should become
reusable.
 Resolve if two nodes happen to have same address.
could arise because of reusability.
Related Work
Perkins et.al - Node i picks random
address. Issues RREQ. if no reply
beyond a timeout, address distinct.
[S]
S
B
E
C
A
H
I
Figure 2.Using routing protocol’s flooding
Related Work
IP address treated as shared resource.
assignment of new IP address requires
approval from all other nodes. Each node
maintains list of used addresses. not
scalable.[ Nesargi et.al]
Zero Configuration
Choose a random address and use ARP
to check for duplication.
Basic Idea
A distributed approach, extending the
functionality of DHCP across all nodes in
an adhoc network.
Dynamically configure each new node also
as a DHCP server.
Add a small address space to each node,
for it to allocate addresses.
Local link address
Use the IPV4 local link address –
169.254/16
Use sub netting.
Net[0].net[1].net[2].net[3].
Of the 16 host bits, set 13 bits for subnet.
Theoretically number of hosts=2^13*8
adhoc nodes.
Sub netting.
Address of the first node
169.254.000.001
Subnet add:
IP Address
Subnet add:
255.255.255.248 11111111.11111111.11111111.11111000
169.254.255.001 11111111.11111111.00000000.00000001
169.254.255.000 11111111.11111111.00000000.00000000
Address of the second node
169.254.000.002
Subnet Allocated to second node
169.254.000.008
Node Configuration
1st Node:
IP:
169.254.000.001
Subnet: 169.254.000.000
2nd Node:
IP:
169.254.000.002
Subnet 169.254.000.008
Figure 3.Configuring Nodes.
Address request
A new node broadcast’s a request with
hop count=1
If more than one neighbor offer’s an
address, use the one with least host part.
The server-node, generates
subnet_request packet, broadcasts.
New Subnet Request
 Includes its subnet value in the request.
 Every receiving node :
 check if subnet value greater than in packet.
 If so, replace with greater subnet in packet
&forward.
 Else if contains reusable subnets, append to packet
and forward.
 Else discard.
 subnet allocated to the new node,
using the reply generated.
State at Each node
 Each node i maintains:
Client
Server’s address.
A lease timer.
Server
For every allocated address, by node i:
maintain subnet address, shutdown timer.
List of un-allocated addresses.
List of released subnet’s.
IP Renewal
If timer expires at both client and server
end & lease not renewed.
Add the address to the free pool at server end.
Subnet reusable after a recovery timeout.
Client sends a 1 hop address request again.
Acquire new address, subnet. Allot existing
clients, new addresses & reset timer (s).
Split
Network Split
Lease timer expires.
adjacent neighbor’s detected could be of
original network or new network.
Irrespective, new address allocated. Network
split gracefully handled.
If no neighbor, first node of new network.
Merger
Network Merger
Assume Network Merger detected.
Node x and y in transmitting range of each
other detect they belong to different networks
One node loses competition, gets new address
and subnet from the other node.
Trigger’s further changes.
Merger is expensive.
Comments
Quick node configuration.
Eliminates random assignment of IP
address. Until a merge occurs ,address
duplication not possible.
Nodes belonging to multiple network
segments.
Proactive?
Questions?