Dynamic Source Routing in Ad
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Transcript Dynamic Source Routing in Ad
Mobile Ad-hoc Networks
-- Overview and a case study
Yinzhe Yu
Oct. 8, 2003
Contents
Introduction on MANET
Recent research topics
Case study: Dynamic Source Routing
What is a MANET ?
Mobile nodes, wireless links
Infrastructure-less: by the nodes,…
Multi-hop routing: …,and for the nodes
Minimal administration: no hassles
Application Example – The Simpson's
Be home early,
Homer.
Hi, Marge.
I miss you.
Dad, you can use
Nelson if I am
too fast.
Yes. What are
you doing,
Nelson?
I can hear u, Lisa.
Can u hear me?
Hmm, A MANET
makes sense.
Why a MANET?
Fast deployment of ad-hoc networks
Special events/conference, military
combat/emergency rescue
What about also cheaper ?
sensor dust, home networking
What’s unique about a MANET ?
Moving nodes ever changing topology
Wireless links
various and volatile link quality
Pervasive (cheap) devices
Power constraints
Security
Confidentiality, other attacks
MANET Protocol Zoo
Topology based routing
Proactive approach, e.g., DSDV.
Reactive approach, e.g., DSR, AODV, TORA.
Hybrid approach, e.g., Cluster, ZRP.
Position based routing
Location Services:
DREAM, Quorum-based, GLS, Home zone etc.
Forwarding Strategy:
Greedy, GPSR, RDF, Hierarchical, etc.
Recent Research Topics
Routing
Better metric, higher throughput
A high-throughput path metric for multi-hop wireless routing. MobiCom 03.
Transport Layer
TCP performance: throughput, fairness, etc.
Enhancing TCP fairness in ad-hoc networks using neighborhood RED. MobiCom 03.
Improving fairness among TCP flows crossing wireless ad-hoc and wired networks.
MobiHoc 03.
MAC Layer
MAC protocol for directional antennas
A MAC protocol for full exploitation of directional antennas in ad-hoc wireless
networks. MobiHoc 03.
Recent Research Topics (cont.)
Security
Reliable routing against malicious nodes
Ariadne: A secure on-demand routing protocol for ad-hoc networks. MobiCom 2002.
Power Management
Power saving and power control
Asynchronous wakeup for ad hoc networks. MobiHoc 2003.
A power control MAC protocol for ad hoc network. MobiCom 2002.
A Case study: Dynamic Source Routing
On-demand
Source Routing
Route Discovery
Route Request
Route Reply
Route Maintenance
Assumption:
Cooperative nodes
Relatively small network diameter (5-10
hops)
Detectable packet error
Unidirectional or bidirectional link
Promiscuous mode (optional)
Route Discovery
B
RREQ FORMAT
Initiator ID
A-B-D-G
A-B-D-G
Initiator seq#
G
Target ID
A-B
A
A-B-D-G
A-B-D
D
A
Partial route
A-C-E
A
H
E
A-B-C
A-C-E
A-C-E
C
A-C
Route Request (RREQ)
A-B-C
F
Route Reply (RREP)
Route Discovery is issued with exponential back-off intervals.
Route Discovery: at source A
A need to send to G
Lookup Cache for route A to G
Start Route
Discovery
Protocol
wait
Route
Discovery
finished
no
Buffer
packet
Continue
normal
processing
Route
found
?
yes
yes
Packet
in
buffer
?
Write route in
packet header
no
don
e
Send
packet to
next-hop
Route Discovery: At an intermediate node
<src,id> in
recently
seen
requests
list?
Accept route
request
packet
yes
Discard
route
request
no
Host’s
address
already in
patrial
route
Append
myAddr to
partial route
Store <src,id>
in list
Broadcast packet
no
no
myAdd
r=targ
et
yes
Send route
reply packet
done
yes
Discard
route
request
Route Maintenance
B
RERR
RERR
G
D
G
A
Route Cache (A)
G: A, B, D, G
G: A, C, E, H, G
F: B, C, F
H
E
C
F
Additional feature #1: Caching Overheard Routes
Node C Cache
E:
E:C,
C,D,
D,EE
A: C, B, A
Z: C, X, Y, Z
V: C, X, W, V
Node A Cache
E: A, B, C, D, E
A
B
C
D
E
V
W
X
Y
Z
Additional feature #2: RREP with Cached Routes
B
RERR
RERR
RREQ
(! D-G)
D
G
A
Route Cache (A)
G: A, B, D, G
F: B, C, F
G:A,C,E,H,G
RREQ
(! D-G)
RREQ
(! D-G)
H
E
RREP
C
Route Cache (C)
G: C, E, D,
H, G
F
Additional feature #3: Packet Salvage
B
RERR
RERR
G
D
A
G
Route Cache (D)
G: D, E, H, G
H
E
C
F
Caution: No double salvage allowed !!!
A Summary of DSR
Entirely on-demand, potentially zero control message
overhead
Trivially loop-free with source routing
Conceptually supports unidirectional links as well as
bidirectional links
High packet delays/jitters associated with on-demand
routing
Space overhead in packets and route caches
Promiscuous mode operations consume excessive
amount of power