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Title: Spanakis%20Manolis%20CS539%20Computer%20Science%20Department%2016/03/2005


1
Spanakis ManolisCS539Computer Science
Department16/03/2005
Mobile Ad-hoc NETworks Routing Protocols
2
The Simpson's
Be home early, Homer.
Hmm, A MANET makes sense.
Yes. What are you doing, Nelson?
Dad, you can use Nelson if I am too fast.
Hi, Marge. I miss you.
I can hear u, Lisa.
Can u hear me?
3
IETF MANET Working Group
  • The Mobile Ad-hoc Networking (manet) Working
    Group is a chartered working group within the
    Internet Engineering Task Force (IETF) to
    investigate and develop candidate standard
    Internet routing support for mobile, wireless IP
    autonomous segments.
  • The charter and official IETF Home Page for manet
    are found at http//www.ietf.org/html.charters/m
    anet-charter.html

4
Description of Working Group
  • Purpose of MANET working group
  • standardize IP routing protocol functionality
    suitable for wireless routing application
    withinboth static and dynamic topologies with
    increased dynamics due to nodemotion or other
    factors.
  • Approaches are intended to be
  • relatively lightweight in nature
  • suitable for multiple hardware and wireless
    environments, and address scenarios
  • MANETs are deployed at the edges of an IP
    infrastructure
  • hybrid mesh infrastructures (e.g., a mixture of
    fixed and mobile routers) should also be
    supported by MANET specifications and management
    features.

5
Description of Working Group
  • Using mature components from previous work on
    experimental reactive and proactive protocols,
    the WG will develop two Standards track routing
    protocol specifications
  • Reactive MANET Protocol (RMP)
  • Proactive MANET Protocol (PMP)
  • Both IPv4 and IPv6 will be supported.
  • Routing security requirements and issues will
    also be addressed.

6
Goals and Milestones
Done Post as an informational Internet-Drafts a discussion of mobile ad-hoc networking and issues.
Done Agenda bashing, discussion of charter and of mobile ad hoc networking draft.
Done Discuss proposed protocols and issues. Redefine charter.
Done Publish Informational RFC on manet design considerations
Done Review the WG Charter and update
Done Submit AODV specification to IESG for publication as Experimental RFC
Done Develop I-D for potential common manet encapsulation protocol approach
Done Submit initial I-D(s) of candidate proposed routing protocols and design frameworks
Done Promote implementation, revision, and testing of initial proposed I-D(s)
Done Explore basic performance and implementation issues of initial approaches
Done Explore proposed proactive protocol design commonalities
Done Submit DSR specification to IESG for publication as Experimental RFC
Done Submit OLSR specification to IESG for publication as Experimental RFC
Done Submit TBRPF specification to IESG for publication as Experimental RFC
Done Develop a further focused problem statement and address an approach for a common engineering work effort
Done Reevaluate the WG's potential based on the problem statement consensus
Mar 05 Submit initial ID of RMP for WG review
Mar 05 Submit initial ID of PMP for WG review
Mar 05 Submit inital ID of generalized MANET flooding approach
Jun 05 Revise WG documents and review
Nov 05 Document initial implementation progress and experience Revise documents based upon implementation experience
Feb 06 Submit RMP specification and supporting documentation to IESG for publications as Proposed Standard
Feb 06 Submit PMP specification and supporting documentation to IESG for publications as Proposed Standard
Feb 06 Submit MANET flooding specification to IESG for publication as Experimental Standard
Mar 06 Review and update milestones
7
Current Status
  • Internet-Drafts
  • The Dynamic Source Routing Protocol for Mobile Ad
    Hoc Networks (DSR) (264775 bytes)
  • Dynamic MANET On-demand Routing Protocol (DYMO)
    (48518 bytes)
  • Request For Comments
  • Mobile Ad hoc Networking (MANET) Routing
    Protocol Performance Issues and Evaluation
    Considerations (RFC 2501) (28912 bytes)
  • Ad Hoc On Demand Distance Vector (AODV) Routing
    (RFC 3561) (90356 bytes)
  • Optimized Link State Routing Protocol (RFC 3626)
    (161265 bytes)
  • Topology Dissemination Based on Reverse-Path
    Forwarding (TBRPF) (RFC 3684) (107963 bytes)

8
Mobile Ad Hoc Networks (MANET)
  • Networks formed by a collection of wireless
    mobile hosts
  • Without any pre-existing infrastructure or the
    aid of any centralized administration
  • Network characteristics change over time
  • Routes between nodes may potentially contain
    multiple hops
  • Number of hosts in the network

9
Mobile Ad Hoc Networks (MANET)
  • May need to traverse multiple links to reach a
    destination

10
Mobile Ad Hoc Networks (MANET)
  • Mobility causes route changes

11
Why Ad Hoc Networks ?
  • Ease and Speed in deployment
  • Decreased dependence on infrastructure
  • Only possible solution to interconnect a group of
    nodes
  • Many Commercial Products available today

12
MANET Applications
  • Body Area Networking
  • body sensors network,
  • Personal area Networking
  • cell phone, laptop, ear phone, wrist watch
  • Emergency operations
  • search-and-rescue (earthquakes, boats,
    airplanes)
  • policing and fire fighting
  • Military environments
  • soldiers, tanks, planes, battlefield
  • Civilian environments
  • taxi cab network
  • meeting rooms
  • sports stadiums
  • boats, small aircraft

13
Variations
  • Traffic characteristics may differ in different
    ad hoc networks
  • bit rate, reliability requirements, unicast,
    multicast, host-based addressing, content-based
    addressing, capability-based addressing
  • Ad-hoc networks may co-exist and co-operate with
    infrastructure-based networks
  • Mobility characteristics may be different
  • Speed, direction of movement, pattern of movement
  • Symmetric vs Asymmetric
  • Nodes capabilities and responsibilities

14
Issues in Mobile Ad-hoc Networks
  • Limited wireless transmission range
  • Broadcast nature of the wireless medium
  • Hidden terminal problem
  • Packet losses due to transmission errors
  • Mobility-induced route changes
  • Mobility-induced packet losses
  • Battery constraints
  • Potentially frequent network partitions
  • Ease of snooping on wireless transmissions
    (security hazard)

15
  • Whats 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

16
  • 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.

17
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.

18
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.

19
Ad-hoc p2p a Comparison
  • P2P is based on an IP network
  • Ad-hoc is based on a mobile radio network
  • Mobile Ad-hoc and Peer-to-Peer Networks hold many
    similarities concerning their
  • routing algorithms and
  • network management principles
  • Both have to provide networking functionalities
    in a completely unmanaged and decentralized
    environment
  • Ie. To determine how queries (packets) are guided
    through the network

20
Ad-hoc p2p a Comparison
21
Ad-hoc p2p - Differences
22
Ad-hoc p2p - Similarities
23
Routing in Mobile Ad-Hoc Networks
24
Routing Overview
  • Mobile wireless hosts
  • Only subset within range at given time
  • Want to communicate with any other node

25
Routing Overview
  • Network with nodes, edges
  • Goal transfer message from one node to another
  • Which is the best path?
  • Who decides - source or intermediate nodes?

26
Which path?
  • Generally try to optimize one of the following
  • Shortest path (fewest hops)
  • Shortest time (lowest latency)
  • Shortest weighted path (utilize available
    bandwidth, battery)

27
Who determines route?
  • Source (path) routing Like airline travel
  • Source specifies entire route
  • Intermediate nodes just forward to specified next
    hop
  • Destination (hop-by-hop) routing Like postal
    service
  • Source specifies only destination in message
    header
  • Intermediate nodes look at destination in header,
    consult internal tables to determine appropriate
    next hop

28
MANET Routing
  • Standardization effort led by IETF Mobile Ad-hoc
    Networks (MANET) task group
  • http//www.ietf.org/html.charters/manet-charter.ht
    ml
  • 9 routing protocols in draft stage, 4 drafts
    dealing with broadcast / multicast / flow issues
  • Other protocols being researched
  • utilize geographic / GPS info, ant-based
    techniques, etc.

29
MANET Routing Properties
  • Qualitive Properties
  • Distributed operation
  • Loop Freedom
  • Demand Based Operation
  • Security
  • Sleep period operation
  • Unidirectional link support
  • Quantitative Properties
  • End-to-End data throughput
  • Delays
  • Route Acquisition time
  • Out of order delivery (percentage)
  • Efficiency

30
MANET Routing Properties
  • No distinction between routers and end nodes
    all nodes participate in routing
  • No external network setup self-configuring
  • Efficient when network topology is dynamic
    (frequent network changes links break, nodes
    come and go)
  • Self Starting
  • Adapt to network conditions

31
Why is Routing in MANET different ?
  • Host mobility
  • link failure/repair due to mobility may have
    different characteristics than those due to other
    causes
  • Rate of link failure/repair may be high when
    nodes move fast
  • New performance criteria are used
  • route stability despite mobility
  • energy consumption
  • host position
  • Dynamic Solution much more difficult to be
    deployed

32
Routing Protocols
  • No Routing
  • Plain Flooding (PF)
  • Proactive protocols determine routes independent
    of traffic pattern, traditional link-state and
    distance-vector routing protocols are proactive.
  • Destination Sequence Distance Vector (DSDV)
  • Link State Routing
  • Reactive protocols discover routes and maintain
    them only if needed.
  • Dynamic Source Routing (DSR)
  • Ad-hoc On-Demand Distance Vector Routing (AODV)
  • Hybrid protocols
  • Zone Based Routing (ZBR)

33
Trade-Offs
  • Latency of route discovery
  • Proactive protocols may have lower latency since
    routes are maintained at all times
  • Reactive protocols may have higher latency
    because a route from X to Y will be found only
    when X attempts to send to Y
  • Overhead of route discovery/maintenance
  • Reactive protocols may have lower overhead since
    routes are determined only if needed
  • Proactive protocols can (but not necessarily)
    result in higher overhead due to continuous route
    updating
  • Which approach achieves a better trade-off
    depends on the traffic and mobility patterns

34
Routing Protocols
35
Flooding for Data Delivery
Y
Z
S
E
F
B
C
M
L
J
A
G
H
R
K
I
N
36
Flooding for Data Delivery
Y
Broadcast transmission
Z
S
E
F
B
C
M
L
J
A
G
H
R
K
I
N
37
Flooding for Data Delivery
Y
Z
S
E
F
B
C
M
L
J
A
G
H
R
K
I
N
38
Flooding for Data Delivery
Y
Z
S
E
F
B
C
M
L
J
A
G
H
R
K
I
N
39
Flooding for Data Delivery
Y
Z
S
E
F
B
C
M
L
J
A
G
H
R
K
I
N
  • Nodes J and K both broadcast packet P to node R
  • Since nodes J and K are hidden from each other,
    their
  • transmissions may collide
  • gt Packet P may not be delivered to node
    R at all,
  • despite the use of flooding

40
Flooding for Data Delivery
Y
Z
S
E
F
B
C
M
L
J
A
G
H
R
K
I
N
41
Flooding for Data Delivery
Y
Z
S
E
F
B
C
M
L
J
A
G
H
R
K
I
N
  • Flooding completed
  • Nodes unreachable from S do not receive packet
  • Flooding may deliver packets to too many nodes
  • (in the worst case, all nodes reachable from
    sender
  • may receive the packet)

42
Flooding for Data Delivery Advantages
  • Simplicity
  • Efficient than other protocols when rate of
    information transmission is low enough
  • overhead of explicit route discovery/maintenance
    incurred is higher
  • small data packets
  • infrequent transfers
  • many topology changes occur between consecutive
    packet transmissions
  • Potentially higher reliability of data delivery

43
Flooding for Data Delivery Disadvantages
  • Very high overhead
  • Data packets may be delivered to too many nodes
    who do not need to receive them
  • Lower reliability of data delivery
  • If Broadcasting is unreliable (ie. 802.11 MAC)

44
Flooding of Control Packets
  • Many protocols perform (potentially limited)
    flooding of control packets, instead of data
    packets
  • The control packets are used to discover routes
  • Discovered routes are subsequently used to send
    data packet(s)

45
Dynamic Source Routing
  • Draft RFC at http//www.ietf.org/internet-drafts/d
    raft-ietf-manet-dsr-07.txt
  • Source routing entire path to destination
    supplied by source in packet header
  • Utilizes extension header following standard IP
    header to carry protocol information (route to
    destination, etc.)

46
DSR Protocol Activities
  • Route discovery
  • Undertaken when source needs a route to a
    destination
  • Route maintenance
  • Detect network topology changes
  • Used when link breaks, rendering specified path
    unusable
  • Routing (easy!)

47
Details
  • Intermediate nodes cache overheard routes
  • Eavesdrop on routes contained in headers
  • Reduces need for route discovery
  • Intermediate node may return Route Reply to
    source if it already has a path stored
  • Encourages expanding ring search for route

48
Details (cont.)
  • Destination may need to discover route to source
    to deliver Route Reply
  • piggyback Route Reply onto new Route Request to
    prevent infinite loop
  • Route Request duplicate rejection
  • Source includes identification number in Route
    Request
  • Partial path inspected for loop

49
Route Maintenance
  • Used when link breakage occurs
  • Link breakage may be detected using link-layer
    ACKs, passive ACKs, DSR ACK request
  • Route Error message sent to source of message
    being forwarded when break detected
  • Intermediate nodes eavesdrop, adjust cached
    routes
  • Source deletes route tries another if one
    cached, or issues new Route Request
  • Piggybacks Route Error on new Route Request to
    clear intermediate nodes route caches, prevent
    return of invalid route

50
Issues
  • Scalability
  • Discovery messages broadcast throughout network
  • Broadcast / Multicast
  • Use Route Request packets with data included
  • Duplicate rejection mechanisms prevent storms
  • Multicast treated as broadcast no multicast-tree
    operation defined
  • Scalability issues

51
Route Discovery in DSR
Y
Z
S
E
F
B
C
M
L
J
A
G
H
D
K
I
N
Represents a node that has received RREQ for D
from S
52
Route Discovery in DSR
Y
Broadcast transmission
Z
S
S
E
F
B
C
M
L
J
A
G
H
D
K
I
N
Represents transmission of RREQ
X,Y Represents list of identifiers appended
to RREQ
53
Route Discovery in DSR
Y
Z
S
S,E
E
F
B
C
M
L
J
A
G
S,C
H
D
K
I
N
  • Node H receives packet RREQ from two neighbors
  • potential for collision

54
Route Discovery in DSR
Y
Z
S
E
F
S,E,F
B
C
M
L
J
A
G
H
D
K
S,C,G
I
N
  • Node C receives RREQ from G and H, but does not
    forward
  • it again, because node C has already forwarded
    RREQ once

55
Route Discovery in DSR
Y
Z
S
E
F
S,E,F,J
B
C
M
L
J
A
G
H
D
K
I
N
S,C,G,K
  • Nodes J and K both broadcast RREQ to node D
  • Since nodes J and K are hidden from each other,
    their
  • transmissions may collide

56
Route Discovery in DSR
Y
Z
S
E
S,E,F,J,M
F
B
C
M
L
J
A
G
H
D
K
I
N
  • Node D does not forward RREQ, because node D
  • is the intended target of the route discovery

57
Route Reply in DSR
  • Route Reply can be sent by reversing the route in
    Route Request (RREQ) only if links are guaranteed
    to be bi-directional
  • To ensure this, RREQ should be forwarded only if
    it received on a link that is known to be
    bi-directional
  • If unidirectional (asymmetric) links are allowed,
    then RREP may need a route discovery for S from
    node D
  • Unless node D already knows a route to node S
  • If a route discovery is initiated by D for a
    route to S, then the Route Reply is piggybacked
    on the Route Request from D.
  • If IEEE 802.11 MAC is used to send data, then
    links have to be bi-directional (since Ack is
    used)

58
Dynamic Source Routing (DSR)
  • Node S on receiving RREP, caches the route
    included in the RREP
  • When node S sends a data packet to D, the entire
    route is included in the packet header
  • hence the name source routing
  • Intermediate nodes use the source route included
    in a packet to determine to whom a packet should
    be forwarded

59
Route Reply in DSR
Y
Z
S
RREP S,E,F,J,D
E
F
B
C
M
L
J
A
G
H
D
K
I
N
  • Node D sends back a Reply (RREP) to S with the
    pathNOTE If node D does not know a rout back to
    S it might be necessary to start its own rout
    discovery to S.

60
Data Delivery in DSR
Y
Z
DATA S,E,F,J,D
S
E
F
B
C
M
L
J
A
G
H
D
K
I
N
Packet header size grows with route length
61
DSR Advantages
  • Routes maintained only between nodes who need to
    communicate
  • reduces overhead of route maintenance
  • Route caching can further reduce route discovery
    overhead
  • A single route discovery may yield many routes to
    the destination, due to intermediate nodes
    replying from local caches

62
DSR Disadvantages
  • Packet header size grows with route length due to
    source routing
  • Flood of route requests may potentially reach all
    nodes in the network
  • Care must be taken to avoid collisions between
    route requests propagated by neighboring nodes
  • insertion of random delays before forwarding RREQ

63
DSR Disadvantages
  • An intermediate node may send Route Reply using a
    stale cached route, thus polluting other caches
  • Increased contention if too many route replies
    come back due to nodes replying using their local
    cache
  • Route Reply Storm problem
  • Reply storm may be eased by preventing a node
    from sending RREP if it hears another RREP with a
    shorter route

64
Ad-hoc On-demand Distance Vector Routing
  • Draft RFC at http//www.ietf.org/internet-drafts/d
    raft-ietf-manet-aodv-10.txt
  • Hop-by-hop protocol intermediate nodes use
    lookup table to determine next hop based on
    destination
  • Utilizes only standard IP header

65
AODV Protocol Activities
  • Route discovery
  • Undertaken whenever a node needs a next hop to
    forward a packet to a destination
  • Route maintenance
  • Used when link breaks, rendering next hop
    unusable
  • Routing (easy!)

66
Route Discovery
  • Route Request
  • Source broadcasts Route Request (RREQ) message
    for specified destination
  • Intermediate node Forward message toward
    destination
  • Route Reply
  • Destination unicasts Route Reply msg to source
  • Intermediate node create next-hop entry for
    destination and forward the reply
  • If source receives multiple replies, uses one
    with lowest hop count

67
Route Maintenance
  • Used when link breakage occurs
  • Detecting node may attempt local repair
  • Route Error (RERR) message generated
  • Contains list of unreachable destinations
  • Sent to precursors neighbors who recently sent
    packet which was forwarded over broken link
  • Propagated recursively

68
Route Requests in AODV
Y
Z
S
E
F
B
C
M
L
J
A
G
H
D
K
I
N
69
Route Requests in AODV
Y
Broadcast transmission
Z
S
E
F
B
C
M
L
J
A
G
H
D
K
I
N
70
Route Requests in AODV
Y
Z
S
E
F
B
C
M
L
J
A
G
H
D
K
I
N
71
Reverse Path Setup in AODV
Y
Z
S
E
F
B
C
M
L
J
A
G
H
D
K
I
N
  • Node C receives RREQ from G and H, but does not
    forward
  • it again, because node C has already forwarded
    RREQ once

72
Reverse Path Setup in AODV
Y
Z
S
E
F
B
C
M
L
J
A
G
H
D
K
I
N
73
Reverse Path Setup in AODV
Y
Z
S
E
F
B
C
M
L
J
A
G
H
D
K
I
N
  • Node D does not forward RREQ, because node D
  • is the intended target of the RREQ

74
Route Reply in AODV
Y
Z
S
E
F
B
C
M
L
J
A
G
H
D
K
I
N
Represents links on path taken by RREP
75
Route Reply in AODV
  • An intermediate node (not the destination) may
    also send a Route Reply (RREP) provided that it
    knows a more recent path than the one previously
    known to sender S
  • To determine whether the path known to an
    intermediate node is more recent, destination
    sequence numbers are used
  • The likelihood that an intermediate node will
    send a Route Reply when using AODV is not as high
    as DSR

76
Forward Path Setup in AODV
Y
Z
S
E
F
B
C
M
L
J
A
G
H
D
K
I
N
Forward links are setup when RREP travels
along the reverse path Represents a link on the
forward path
77
Data Delivery in AODV
Y
DATA
Z
S
E
F
B
C
M
L
J
A
G
H
D
K
I
N
  • Routing table entries used to forward data
    packet.
  • Route is not included in packet header.

78
Why Sequence Numbers in AODV
  • To avoid using old/broken routes
  • To determine which route is newer
  • To prevent formation of loops
  • Assume that A does not know about failure of link
    C-D because RERR sent by C is lost
  • Now C performs a route discovery for D. Node A
    receives the RREQ (say, via path C-E-A)
  • Node A will reply since A knows a route to D via
    node B
  • Results in a loop (for instance, C-E-A-B-C )

79
Summary AODV
  • Routes need not be included in packet headers
  • Nodes maintain routing tables containing entries
    only for routes that are in active use
  • At most one next-hop per destination maintained
    at each node
  • DSR may maintain several routes for a single
    destination
  • Unused routes expire even if topology does not
    change

80
Hybrid Protocols
81
Zone Routing Protocol (ZRP)
  • Zone routing protocol combines
  • Proactive protocol which pro-actively updates
    network state and maintains route regardless of
    whether any data traffic exists or not
  • Reactive protocol which only determines route to
    a destination if there is some data to be sent to
    the destination

82
ZRP Example withZone Radius d 2
S performs route discovery for D
S
D
F
Denotes route request
83
ZRP Example with d 2
S performs route discovery for D
S
D
F
E knows route from E to D, so route request need
not be forwarded to D from E
Denotes route reply
84
ZRP Example with d 2
S performs route discovery for D
S
D
F
Denotes route taken by Data
85
Implementation Issues
86
Implementation IssuesWhere to Implement Ad Hoc
Routing
  • Link layer
  • Network layer
  • Application layer

87
Issues inMobile Ad Hoc Networking
  • Issues other than routing have received much less
    attention so far
  • Other interesting problems
  • Address assignment problem
  • MAC protocols
  • Improving interaction between protocol layers
  • Distributed algorithms for MANET
  • QoS issues
  • Applications for MANET
  • Algorithms for dynamic networks
  • Security
  • Privacy, Authentication, Authorization, Data
    integrity
  • Ad-Hoc Sensor networks
  • Addressing based on data (or function) instead of
    name, send this packet to a temperature sensor

88
Related Standards Activities
89
Internet Engineering Task Force (IETF) Activities
  • IETF manet (Mobile Ad-hoc Networks) working group
  • http//www.ietf.org/html.charters/manet-charter.ht
    ml
  • IETF mobileip (IP Routing for Wireless/Mobile
    Hosts) working group
  • http//www.ietf.org/html.charters/mobileip-charter
    .html
  • IETF PILC (Performance Implications of Link
    Characteristics) working group
  • http//www.ietf.org/html.charters/pilc-charter.htm
    l
  • http//pilc.grc.nasa.gov

90
Related Standards Activities
  • BlueTooth
  • http//www.bluetooth.com
  • HomeRF
  • http//www.homerf.org
  • IEEE 802.11
  • http//grouper.ieee.org/groups/802/11/
  • Hiperlan/2
  • http//www.etsi.org/technicalactiv/hiperlan2.htm

91
DYMO
  • Dynamic MANET On-demand Routing Protocol (DYMO)
  • Ian Chakeres
  • Elizabeth Belding-Royer
  • Charlie Perkins
  • The Dynamic MANET On-demand (DYMO) routing
  • protocol is intended for use by mobile nodes in
  • wireless multihop networks. It offers quick
  • adaptation to dynamic conditions, low processing
  • and memory overhead, low network utilization, and
  • determines unicast routes between nodes within
    the
  • network.

92
  • The Dynamic MANET On-demand (DYMO) routing
    protocol enables dynamic, reactive, multihop
    routing between participating nodes wishing to
    communicate. The basic operations of the protocol
    are route discovery and management. During route
    discovery the originating node causes
    dissemination of a Routing Element (RE)
    throughout the network to find the target node.
    During dissemination each intermediate node
    creates a route to the originating node. When the
    target node receives the RE it responds with RE
    unicast toward originating node. During
    propagation each node creates a route to the
    target node. When the originating node is reached
    routes have been established between the
    originating node and the target node in both
    directions. In order to react quickly to changes
    in the network topology nodes should maintain
    their routes and monitor their links. When a
    packet is received for a route that is no longer
    available the source of the packet should be
    notified. A Route Error (RERR) is sent to the
    packet source to indicate the current route is
    broken. Once the source receives the RERR, it
    will re-initiate route discovery if it still has
    packets to deliver. In order to enable extension
    of the base specification, DYMO defines the
    handling of unsupported extensions. By defining
    default handling, future extensions are handled
    in a predetermined understood fashion. DYMO uses
    sequence numbers to ensure loop freedom 3. All
    DYMO packets are transmitted via UDP on port TBD.
    Chakeres, et al. Expires July 5, 2005

93
Goals
  • Create a unicast route
  • Simple, small
  • Easy to implement
  • Extendable
  • Enhancements optimizations
  • IPv4 and IPv6
  • Basic internet connectivity
  • Use what we know

94
Route Discovery
  • Routing Element (RE)
  • Simple, common processing
  • REBlock
  • RREQ gt RE A1 MANETcast
  • RREP gt RE A0 Unicast hop-by-hop
  • Path accumulation
  • Optional accumulation, processing and
    transmission

95
Route Maintenance
  • Avoid expiring good routes
  • Update reverse route lifetime on data reception
  • Update forward route lifetime on data
    transmission
  • Inform sources of broken routes quickly
  • Active links must be monitored
  • Several mechanisms available
  • Route Error (RERR)
  • Optional additional invalid routes

96
DYMO Short Term Goals
  • dymo-00 available
  • feedback already received (more expected)
  • dymo-01soon
  • MANET list discussion
  • Simple, quick implementation
  • Looking for DYMO implementers
  • Simulators and various OS
  • Please contact us
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