Giao thc nh tuyn mng MANET

Mng MANET lMobile Adhoc Network. lGm cc thit b di ng, kt ni khng dy lMulti-hop routing

Thch thc trong nh tuyn cho mng MANET lCn nh tuyn ng Topo thay i rt thng xuyn

lCn gi lng thng tin iu khin nh tuyn ti thiu Wireless bng thng thp Mobile nng lng thp Cn gim thiu s lng cc gi tin iu khin nh

tuyn Cn gim thiu lng thng tin trng thi lu ti mi

nt.

Cc giao thc nh tuyn trong mng MANET lTopology based routing Proactive approach, e.g., DSDV. Reactive approach, e.g., DSR, AODV, TORA. Hybrid approach, e.g., Cluster, ZRP.

l Position based routing Location Services: lDREAM, Quorum-based, GLS, Home zone etc.

Forwarding Strategy: lGreedy, GPSR, RDF, Hierarchical, etc.

Routing Protocols l Reactive (On-demand) protocols Khm ph ng i khi cn Qu trnh tm kim c khi to t ngun

l Proactive protocols Tm kim ng i ngn nht theo cc giao thc nh tuyn

phn tn truyn thng Cn cc qu trnh cp nht thng tin nh tuyn thng

xuyn. Lng thng tin iu khin nh tuyn ln

l Vn cn i gia 2 phng php Thng lng cp nht trng thi vs. thng lng khm

ph ng i nh tuyn d liu theo cc tuyn ng c vs. tr khi khm

ph ng i.

Reactive (on-demand) Routing

lMc tiu: Gim routing overhead lKhng to trc mt cu trc nh tuyn

no l2 phng php pht hin ng i nh tuyn ngun Hc ngc

lNhc im: gy tr do qu trnh khm ph ng.

Reactive (on-demand) routing: lnh tuyn khi cn

0

5

1

2

4

3

query(0)

query(0)

query(0)

query(0)

query(0)

query(0)

query(0)

reply(0)

reply(0)

reply(0)

u im: Khng cn cc cp nht nh k Thch nghi vi s thay i ng ca mng

Nhc im: l Overhead do pht tn thng tin

khm ph ln tr n thi im tm c ng i ln.

Reactive Routing nh tuyn ngun l Ngun s pht tn (kiu ngp lt) trong mng bn

tin route request khi c yu cu v ng i n mt ch. Pht tn xut pht t ngun Ngp lt = mi nt trong mng u nhn c yu cu

1 ln l ch tr li bng cch gi bn tin route reply Tr li bng cch s dng ng i xc nh bi route

request Thit lp ng chuyn d liu

l 2 giao thc c trng: DSR and AODV

Dynamic Source Routing (DSR) lCooperative nodes lRelatively small network diameter (5-10 hops) lDetectable packet error lUnidirectional or bidirectional link lPromiscuous mode (optional)

A

B

C

E

D

G

H

F

A

A

A-B

A-C

A-C-E

A-C-E A-C-E

A-B-D

A-B-D-G A-B-D-G A-B-D-G

Route Discovery

A-B-C

A-B-C

Route Request (RREQ)

Route Reply (RREP)

Route Discovery is issued with exponential back-off intervals.

Initiator ID

Initiator seq#

Target ID Partial route

RREQ FORMAT

Route Discovery: ngun A A need to send to G

Lookup Cache for route A to G

Route found

?

Start Route Discovery Protocol

Continue normal

processing

Route Discovery finished

Packet in

buffer?

Send packet to next-hop done

Buffer packet

no

Write route in packet header

yes

yes

no

wait

Route Discovery: nt trung gian

Accept route request packet

in recently

seen requests

list?

Discard route

request

yes

no Hosts address

already in patrial route

Discard route

request

yes

Store in list

Broadcast packet

Send route reply packet

done

myAddr=targ

et

no Append myAddr to

partial route no

yes

DSR - Route Discovery l Route Reply cha thng tin ng i tm c c

gi bi ch hoc nt trung gian c ng i b phn n ch

l Mi nt cha mt Route Cache cha cc bn ghi ng i m nuts ny hc c (nhn c) trong qu trnh hot ng

Duy tr ng i l ng i c duy tr ch khi n vn ang c s

dng l Pht hin li: Kim sot tnh hp l ca cc ng i ang c bng cch

nghe th ng cc qu trnh truyn d liu ca cc nt hng xm

Nh c ch ACK ca tng thp hn. l Khi pht hin c vn , gi bn tin Route Error v

ngun thc hin mt qu trnh khm ph ng i mi.

A

B

C

E

D

G

H

F

G

RERR RERR

Route Cache (A) G: A, B, D, G G: A, C, E, H, G F: B, C, F

Duy tr ng i

Tm tt v DSR

" Hon ton on-demand, ni chung khng gy overhead " Loop-free " source routing " H tr c lin kt unidirectional v bidirectional. " C tr truyn/jitters gy ra do on-demand routing " i hi khng gian lu tr ng i trong caches

AODV Routing Protocol

l AODV = Ad Hoc On-demand Distance Vector l Ngun gi ngp lt route request i ton mng. l ch D l Tuyn ng ngc v ngun c xc nh khi

mt nt nhn c route request. l Mi nt ch forward gi tin request 1 ln (pure

flooding).

A

S E F

B

C

G D

AODV Route Discovery

A

S E F

B

C

G D

l Ngun gi ngp lt gi tin route request l Mi nt ch forward gi tin route request 1 ln (pure

flooding).

AODV Route Discovery

A

S E F

B

C

G D

l Reverse paths c to khi mt nt nhn c mt gi route request.

AODV Route Discovery

lRoute reply forwarded via the reverse path.

A

S E F

B

C

G D

AODV Route Discovery

lRoute reply c chuyn ngc v ngun s dng reverse path do to lp forward path

lForward path c dng vn chuyn d liu t ngun n ch sau ny.

A

S E F

B

C

G D

Vn ht hn ca tuyn ng

lng i khng s dng s ht hn theo timers. ng i c lu trong bng nh tuyn

khi cha ht hn

A

S E F

B

C

G D

AODV

lMt nt trung gian bit ng i ti ch s tr li li ngun bng cch gi gi tin route reply Gip qu trnh tm ng i din ra nhanh hn.

lTuy nhin hnh thc tr li ny c th gy ra lp khi c cc kt ni b li. Kt ni b li t nt trung gian n ch trong khi nt

ny khng bit.

AODV: Lp do li

l Gi s, C-D b li nt A khng bit (do gi tin Route error t C b mt).

l C thc hin route discovery tm ng n D. l Nt A nhn c RREQ (qua ng C-E-A) l Nt A tr li v A bit ng i ti D qua B l Kt qu to ra ng i c lp t C-D: C-E-A-B-C

A B C D

E

AODV: S dng Sequence Numbers lMi nt X c mt s sequence number Hot ng nh mt nhn thi gian Seq# tng mi khi X gi mt gi tin (c th l RREQ

hoc RREP)

lMi tuyn ng n X (ti nt Y) cng c Seq# l s Seq# mi nht ca X m Y bit.

lSeq# th hin tnh ti ca mt tuyn ng Cng ln th cng ti

AODV: S dng Sequence Numbers

lTrnh lp: Nt trung gian gi RREP (thay v forward RREQ) ch khi n c mt tuyn ng c seq# ln hn seq# trong bn tin RREQ.

S Y D ?

Dest seq. no. = 10 Has a route to D with seq. no = 7 Seq. no. = 15

RREQ carries 10 Y does not reply, but forwards the RREQ

Trnh lp

l S kin li trn lin kt C-D lm cho tng DSN C (s tng ln 10).

l Nu C cn mt ng i n D, n s pht bn tin RREQ vi DSN (10).

l A s khng tr li v DSN ca n

Duy tr ng i

l Cc nt khng nm trn cc tuyn ng active di chuyn th cng sinh ra s kin g

l Nu ngun di chuyn khi to li qu trnh khm ph ng i l Khi ch hoc cc nt trung gian di chuyn

Mt s lin kt b t Nt pha u lin kt b t broadcast gi tin Route Error (RERR) RERR cha danh sch tt c cc ch khng th i n c do lin

kt b t

Source

Destination 1

2

3

4

3

Source

Destination 1

2 4

3

Tm tt v AODV lAODV duy tr ti a 1 tuyn ng cho 1 ch Khi 1 lin kt t, tt c cc tuyn ng s dng

lin kt b xa.

lTuyn ng ht hn theo c ch timeout. lS dng Seq trnh lp.

Acknowledgements lDSR Slides: Yinzhe Yu (umn.edu)