fault-tolerant papers broadband network & mobile communication lab course: computer...
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Fault-Tolerant Papers
Broadband Network & Mobile Communication LabCourse: Computer Fault-Tolerant
Speaker: 邱朝螢Date: 2004/4/20
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Papers Based on DSR Performance Enhancement of Ad Hoc
Networks with Localized Route Repair (2003 IEEE Transaction Journal)
An Extended Dynamic Source Routing Scheme in Ad Hoc Wireless Networks (2002 IEEE Proceedings of the 35th Annual Hawaii International Conference)
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Papers Based on AODV AODV-BR : Backup Routing in Ad Hoc
Networks (2000 Proceedings of the IEEE Wireless Communications and Networking Conference)
AODV-PA : AODV with Path Accumulation (2003 IEEE International Conference)
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Outline Introduction concept of the four papers. Simulation of papers. Compare the papers.
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Request Zone : The zone in which the route-repair packet propagates is known as the “request zone”
LRR consists of two major component The radius of request zone is two hops Next-to-Next (NN)
Localized Route Repair (LRR)
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destination
source
A
B
CD
Request Zone
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Request Zone
destination
source
A
B
C
D
hop1
hop1
hop1hop1
hop2
hop2
hop2hop2
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Next-to-Next (NN) Information about next-to-next node is
stored at each intermediate node along the path.
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Localized Route Repair (LRR) A node start a timer when it sends out the non-
propagating route request. Timer times out, if it receives a reply
It sends all the subsequent packets through that node
Else, it exits and allows the route maintenance mechanism to find a new route
It also piggybacks the information about the change in route on one of data packets and an acknowledgment toward the source.
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Localized Route Repair (LRR) Thus, the route is repaired and the information is
distributed to all the nodes on the route. The strategy repairs the route on the fly in the
shortest possible time, since the data packets are cached at the intermediate node for that time, retransmission of the partial data by the source is avoided.
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Simulation Random Waypoint Model Simulation Range
1500*300 meters Number of node in the range
Random creating 50 nodes Traffic source
CBR (Content Bit-Rate) Pause time
0~900 second
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Simulation Metric Routing Overhead / Pause Time Packet Delivery Ratio / Pause Time Average Delay / Pause Time
(End-to-End delay of data packets)
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Extended Dynamic Source Routing Find two disjoint path between the source
and the destination of a routing process without introducing extra overhead.
The paper proposal that modifies DSR’s RREQ process
Two disjoint route path Black route (nodes exclude source and
destination in the route color black ) White route (nodes exclude source and
destination in the route color white )
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Extended Dynamic Source Routing Each intermediate node can be colored
only once and the destination can be colored twice with one for each color.
Each host maintain a list of (source, destination, request_id, color)
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Extended Dynamic Source Routing Each sender s initially broadcasts two request (s,
d, id, black) and (s, d, id, white) When an intermediate host v receives a route
packet (s, d, id, color) If v has been marked for (s, d, id) then the request
will discarded. Else, the request is kept for time before making v △
for (s, d, id) If v does not receive a route request (s, d, id, ‘color), then v
is marked color for (s, d, id) Else, v is randomly marked either white or black
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destination
source
EDSR
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Simulation Not in NS2 Simulation Range
100 * 100 meters Number of node in the range
Random creating 0~100 nodes Node radius
15 , 25 , 50 , 75
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Compare Above Two Papers Modify DSR
First paper modifies flooding range when a RERR occurs.
Second paper modifies route discovery/reply.
Purpose First paper presents a Localized Route Repair ( LRR)
technique which repairs a route on the fly as soon as it is broken.
Second paper presents a technique to find two disjoint route when source node want to forward data to destination node.
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AODV-BR The paper proposes a scheme to improve
AODV by creating a mesh and providing multiple alternate routes.
The paper proposal that modifies AODV’s RREP process.
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AODV-BR Overhear
A node promiscuously “overhears” packets that are transmitted by their neighboring nodes.
A node obtains alternate path information and becomes part of the mesh as follows.
When a node that is not part of the route overhears a RREP packet not directed to itself transmitted by a neighbor, it records that neighbor as the next hop to the destination in its alternate route table.
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destination
source
A
B
D
RREQ
C
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destination
source
A
B
D
RREPRREP
C
E
E Overhear RREP
F
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RERR
destination
source
A
C
D
B
D broadcast to find a route to F
E
F
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Simulation Random Waypoint Model Simulation Range
1500*300 meters Number of node in the range
Random creating 50 nodes Traffic source
CBR (Content Bit-Rate) Pause time
0~300 second
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Simulation Metric Packet Delivery / Pause Time End-to-End Delay / Pause Time Number of Data Transmitted/Data Received
/ Pause Time
(Routing Overhead)
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AODV and DSR RREQ Process AODV
DSR
A B C D E
A A, B A,B,C
A,B,C,D
A B C D E
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AODV Routing table entry
Destination Next hop Number of hops (metric) Sequence number for the destination Active neighbors for this route Expiration time for the route table entry
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Improving AODV AODV Advantage
Nodes periodically exchange hello message. Nodes (not on a selected path) don’t maintain
routing information or participate in routing table exchanges.
AODV Disadvantage Nodes can not know other nodes exclude it’s
neighbors. A old route in source node is difficult to
maintain.
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Path Accumulation in AODV
A B C D E
RREQ A A, B A,B,
CA,B,C,D
ED,E
C,D,E
B,C,D,E
Node C, D, E can get the route information to maintain it’s routing table
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Simulation Random Waypoint Simulation Range
1000*1000 meters with 50 nodes 1500*1500 meters with 100 nodes
Traffic source CBR (Content Bit-Rate)
Total time 600 second
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Simulation Metric Packet Delivery Ratio Normalized Routing Load
(Routing Overhead) End-to-End Delay of Data packets
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Compare Above Two Papers Modify DSR
First paper modifies RREP Second paper combine AODV and DSR
Purpose First paper establish alternate route table to
find a new route when the route occur failure. Second paper employ DSR’s RREQ format to
improve AODV’s routing table.