提出 Loop Free Multi-Path Routing 協定

• why:1. 行動節點傳輸距離限制和任意移動

造成路徑中斷和拓樸改變2.減少重找路的成本3.Loop Free P9

模擬比較 Ant Mobility model(trace model) 和 RandomWay Mobility model(synthetic model)

（使用 DSDV DSR AODV ）• why:• 分析無線網路的繞路效能，需 Mobility Model 模

擬行動節點的移動性• Mobility Model 有 2 種：軌跡（ trace ）和合成

（ synthetic ）不同環境有不同移動模組，要記錄這些行動節點的軌跡資料是不易的，所以模擬皆用合成，但軌跡模組較精準

AODV(1/5)

• Each node maintain routing table• Format of routing table

• Format of control packets• RREQ

• RREP

source RequestID dest Seq-num hops

source dest Seq-num hops

dest Next-hops Seq-num hops

AODV(2/5)

• Seq-num (Sequence number): 由 source 得到 destination 的 route 最新順序號碼（ ex:time ），越大越新 ，由 destination counter 所給，初始為 0

• RequestID ： source 的計數器，每廣播一次 Route Request 遞增

• Source 加 RequestID 唯一可識別 RREQ ，判斷重複封包

AODV(3/5)

Route discovery procedure• Source : broadcast a RREQ to its neighbors• Intermediate node receive RREQ:

1. 在 history table 比對 (Source , RequestID)

2.If It has route to dest and Seq-num is bigger, it send back RREP to source

3.Otherwise it build a reverse link in its routing table with a timer and re-broadcast RREQ

• Dest receive RREQ : copy source , dest and hops of RREQ to RREP and get Sequence number in memory counter

AODV(4/5)

Route reply procedureDest : send RREP to source along reverse li

nkIntermediate node receive RREP: It build a f

orward link to dest and send RREP to source along reverse link

Source :create entry

AODV(5/5)

• Routing table maintenance• 每個節點定期廣播一個 hello message 給 neighbors 並回應，

無回應則表示節點不直接連接

• Active neighbor （有效鄰近節點） : 紀錄最近某段時間內，對 dest 送來封包之鄰近節點

• 檢查會經過此消失節點的路，有效鄰近節點會被告知此路不通，需清除路由表，有效鄰近節點會再告知其有效鄰近節點

dest Next-hops Seq-num hops Active neighbor

DSR

• DSR 和 AODV 主要的不同在於 RREQ 、RREP 和 RERR 具有 complete path from source to destination

LFMPR(1)

• Base on AODV

• Use DSR concept to construct multiple paths

• Path: complete path of a packet passing through

• 無 source and RequestID

LFMPR(2)

• RREQ

• RREP

• RERR

• Routing table

dest Next-hop hops Seq-num path

dest Next-hop hops Seq-num Flow-id path

dest Next-hop hops Seq-num Unreach-dest

dest Next-hop hops Seq-num Flow-id S-flag S-flow-id path

LFMPR(3)

Route discovery procedure

• Source :

• If no entry, it queue the data packet

• Generate RREQ and add node ID in path

• broadcast a RREQ to its neighbors

LFMPR(4)

• Intermediate node receive RREQ:

1. record more than one(max m) reverse link (multi-reverse link)and path field in routing table

2.If It has route to dest and Seq-num is bigger, it send back RREP to source

3.Otherwise it build a reverse link in its routing table with a timer and add node ID in path field and re-broadcast RREQ once

LFMPR(5)

• Dest receive RREQ : copy source , dest , hops and path of RREQ to RREP and get Sequence number in memory counter

LFMPR(6)

Route reply procedureDest : send RREP to source along reverse li

nkIntermediate node receive RREP: 1.Complete the multi-reverse link2.if RREP has flow-id ,record it to S-flow-id 3.New a flow-id for each multi-reverse link a

nd add it in RREP3.Send RREP to each multi-reverse link

LFMPR(7)

• Source : add flow-id in the data packet and forward it

• EX:P13 P16

• S-flag is indicate that the flow-id in a data packet must switch to s-flow-id during the data forwarding phase

LFMPR(7/7)

• Routing table maintenance• If transmission is broken, intermediate

choose backup path and change flow-id of data packet and forward next hop

• If it has no entry to destination (unreachable) , it broadcast RERR packet to neighbors and they remove entry in routing table

• P17

The Performance analysis of LFMPR

Metrics suggested by IETE MANET working group for routing protocol evaluation

1.throughput ratio

2.Average End-to-end Delay

3.Normalized Routing Load

throughput ratio P20

• The radio of data packet received by destination

• LFMPR is higher than AODV

• Current routing path broken, packets be sent with another path without performing any queue procedure which increasing the throughput ratio

Average End-to-end Delay P21

• Average End-to-end Delay of data packets includes buffering during route discovery, queuing delay, retransmission delay

• Average End-to-end Delay in LFMPR is less than that in AODV

• Because once the transmission path breaks, the intermediate node chooses backup path immediately for sending the data

Normalized Routing Load

• Total number of control messages (RREQ,RREP,RRER)

• RREQ (P22) is less: path broken

• RREP(P22) is more: construct multiple paths (multi-reverse links)

• RERR(P23)is grown slowly: path broken ,the intermediate nodes need to broadcast a RERR packet

RandomWay Mobility model(synthetic model)

• A mobility model includes the change in speed and direction of each MNs

• The movement of each mobile node • 1.It selects a random destination• 2.Select a random speed• 3.move to destination• 4.After reaching the destination• 5.pause a random time• 6.repeat1.

Ant Mobility model (trace model)

• P27

• 給參數 map size, ant size ,food size, etc to a tool( ant mobility model) P31

• 他將模擬 ant 移動（ ant 為 mobile node ），記錄移動方向和速度於一個 TCL 檔，給 NS2 模擬 P29

評估 3 項優點1.throughput ratio

2.Average End-to-end Delay

3.Normalized Routing Load

發現 ant mobility model 都較好