fault-tolerant papers broadband network & mobile communication lab course: computer...

Fault-Tolerant Papers

Broadband Network & Mobile Communication LabCourse: Computer Fault-Tolerant

Speaker: 邱朝螢Date: 2004/4/20

2Broadband Network & Mobile Communication LabBroadband Network & Mobile Communication Lab

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)


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)


Outline Introduction concept of the four papers. Simulation of papers. Compare the papers.

Performance Enhancement of Ad Hoc Networks with Localized

Route Repair


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)


destination

source

A

B

CD

Request Zone


Request Zone

destination

source

A

B

C

D

hop1

hop1

hop1hop1

hop2

hop2

hop2hop2


Next-to-Next (NN) Information about next-to-next node is

stored at each intermediate node along the path.


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.


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.


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


Simulation Metric Routing Overhead / Pause Time Packet Delivery Ratio / Pause Time Average Delay / Pause Time

(End-to-End delay of data packets)

An Extended Dynamic Source Routing Scheme in Ad Hoc

Wireless Networks


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 )


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)


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


destination

source

EDSR


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


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.

AODV-BR : Backup Routing in Ad Hoc Networks


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.


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.


destination

source

A

B

D

RREQ

C


destination

source

A

B

D

RREPRREP

C

E

E Overhear RREP

F


RERR

destination

source

A

C

D

B

D broadcast to find a route to F

E

F


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


Simulation Metric Packet Delivery / Pause Time End-to-End Delay / Pause Time Number of Data Transmitted/Data Received

/ Pause Time

(Routing Overhead)

AODV-PA : AODV with Path Accumulation


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


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


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.


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


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


Simulation Metric Packet Delivery Ratio Normalized Routing Load

(Routing Overhead) End-to-End Delay of Data packets


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.

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