42Route 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
43Route Discovery in DSR Y Broadcast Z [S] S E F B C M L J A G H D K I N Represents transmission of RREQ[X,Y] Represents route record stored in RREQ
44Route Discovery in DSR Y Z S [S,E] E F [S,B] B C M L J A G [S,C] H D K Node H receives packet RREQ from two neighbors:potential for collision
45Route Discovery in DSR Y Z S E F B [S,E,F] C M L [S,B,A] J A G [S,B,H] K[S,C,G]INC receives RREQ from G and H, but does not forwardit again, because C has already forwarded RREQ once
46Route Discovery in DSR Y Z S E F [S,E,F,J] B C M L J A G H [S,B,H,I] D KIN[S,C,G,K]J and K both broadcast RREQ to DTheir transmissions may collide at D
47Route Discovery in DSRYZSE[S,E,F,J,M]FBCMLJAGHDKIND does not forward RREQ, because D is the intended target
48Route 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 Represents RREP control message
49An Example of Route Maintenance BASEFHJDCGIKZYMNLRERR [J-D]Route Error Packet : RERRJ sends a route error to S along route J-F-E-S when it finds link [J-D] brokenNodes hearing RERR update their route cache to remove all invalid routes related with link J-D
50Use of Route Caching Can Speed up Route Discovery BASEFHJDCGIKZMNL[S,E,F,J,D][E,F,J,D][C,S][G,C,S][F,J,D],[F,E,S][J,F,E,S]RREQ[K,G,C,S]RREPWhen node Z sends a route request for node C, node K sends back a routereply [Z,K,G,C] to node Z using a locally cached route
51Use of Route Caching Can Reduce Propagation of Route Requests BASEFHJDCGIKZMNL[S,E,F,J,D][E,F,J,D][C,S][G,C,S][F,J,D],[F,E,S][J,F,E,S]RREQ[K,G,C,S]RREP[D,K,G,,C]Route Replies (RREP) from node K and D limit flooding of RREQ.
62Reverse Path Setup in AODV YZSEFBCMLJAGHDKINNode D does not forward RREQ, because node Dis the intended target of the RREQ
63Forward Path Setup in AODV YZSEFBCMLJAGHDKINForward links are setup when RREP travels alongthe reverse pathRepresents a link on the forward path
64Route Maintenance123SDRERR3´The link from node 3 to D is broken as 3 has moved away to a position 3´.Node 2 sends a RERR message to 1 and 1 sends the message in turn to S.S initiates a route discovery if it still needs the route to D.