FAMU-FSU COLLEGE OF ENGINEERING Department of Electrical and Computer Engineering Students: Hung Khong – Derek Vollmer Students: Hung Khong – Derek Vollmer Instructor: Dr Ming Yu Instructor: Dr Ming Yu 04-2008 04-2008 Computer Network Project The Dynamic Source Routing Protocol for Ad Hoc Networks
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FAMU-FSU COLLEGE OF ENGINEERING Department of Electrical and Computer Engineering
FAMU-FSU COLLEGE OF ENGINEERING Department of Electrical and Computer Engineering. Computer Network Project The Dynamic Source Routing Protocol for Ad Hoc Networks. Students: Hung Khong – Derek Vollmer Instructor: Dr Ming Yu 04-2008. Content. Description of DSR routing protocols. - PowerPoint PPT Presentation
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FAMU-FSU COLLEGE OF ENGINEERINGDepartment of Electrical and Computer Engineering
Students: Hung Khong – Derek VollmerStudents: Hung Khong – Derek VollmerInstructor: Dr Ming YuInstructor: Dr Ming Yu
04-200804-2008
Computer Network Project
The Dynamic Source Routing Protocol for Ad Hoc Networks
Description of DSR routing protocols Description of DSR routing protocols
• DSR Definition: – A send packets to E, the router to E is embedded in A’s header. Intermediate node uses this source route
to determine to whom the packet should be forwarded.– Different packets may have different routers.
• All nodes are willing to forward packets for other nodes in the network
• The diameter of a network will not be too large
• The node’s speed is moderate and nodes may move at any time without notice
• All nodes are overhearing (promiscuous) increase power consumption.
Description of DSR routing protocols Description of DSR routing protocols
1- Introduction to DSR 1- Introduction to DSR
• Every RREQ packet contains (initiator & target address, route record, request ID)• Each node maintains a list of (initial add. & request id)• When an intermediate node X receives a RREQ:
Discard RREQ if RREQ’s (initial add. & request id) is in node’s list Returns a route reply packet which contains a route from initiator to target
• If X is the target node• If X has an entry in its route cache for the route to target
Appends itself address to the route record in RREQ and re-broadcast RREQ
• Uses exponential back-off algorithm to limit the rate of RREQ to reduce the overhead
Description of DSR routing protocols Description of DSR routing protocols
• E on receiving the first RREQ, sends a Route Reply (RREP) including the route from A to E
• RREP packet is sent to A by: – Route Reply can be sent by reversing the route in RREQ If links are bi-directional – If unidirectional (asymmetric) links are allowed, then a route to A is needed
Local route cache has a route to A Piggybacking Route Reply in Route Request packet for A
– Perform its own RREQ for target node A
• If IEEE 802.11 MAC is used, then links have to be bi-directional• Route Caching : each node caches a new route it learns by all means
Description of DSR routing protocols Description of DSR routing protocols
• E sends a route error to A along route E-D-B-A when it finds link [E-F] broken• Nodes hearing RERR update their route cache to remove all invalid routes related
with link E-F• How to find link [E-F] is down:
– MAC level ack – Passive acknowledge (overhearing neighbor node transmission)– Insert a bit in packet’s header to request a DSR specific ack returned by next hop.
• How to send RRER packet to A:– Use reverse route– Use intermediate node ‘s route cache to get to node A– Piggybacking RRER packet in route discovery packet A
Description of DSR routing protocols Description of DSR routing protocols
4- Route Maintenance4- Route Maintenance
• Simulation Topology: Ad-hoc network of 50 mobile nodes moving randomly within flat rectangular 1500x300m
• Simulation time: 900 seconds• Data traffic : CBR UDP traffic source with 20 sources• Data rate: 4 256-byte packets/s• Radio channel: Lucent WaveLAN • Node movement velocity: 1 m/s and 20 m/s• Node Pause time: 0:100:900 (s)
• Given a certain packet size, the protocol performs as expected.
• DSR on-demand protocol has low routing-overhead.
• Conduct further investigation of packet size influencing delivery ratio and the effect of denser topologies.
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Lessons LearnedLessons Learned
• The cbrgen read-me file claims argument –s is max speed when it is speed type. –M is for max speed.
• When simulating DSR, one must use CMUPriQueue or a segmentation fault will occur.
• The send rate parameter at the top of the scenario file is the inverse of the rate argument in the command. When looking at other people’s results, we noticed they claimed 4 packets/s, but sent the same number of packets corresponding to a send rate of 4 (0.25 Packets/s).