[PPT] - Ad-Ho c On-Demand Distance V ector Routing Charles E. P PowerPoint Presentation

SLIDE 1 P erkins, Ro y er 1 Sun, UCSB Ad-Ho c On-Demand Distance V ector Routing Charles E. P erkins Adv anced Net w

rk

Dev elopmen t Sun Microsystems Menlo P ark, CA cp erkins@eng.sun.com Elizab eth Ro y er Dept

f

Electrical & Computer Engineering Univ ersit y

f

California San ta Barbara, Univ ersit y

f

California ero y er@alpha.ece.uscb.edu

SLIDE 2 P erkins, Ro y er 2 Sun, UCSB What an ad-ho c routing proto col needs

Multi-hop

paths

Self-starting
Dynamic

top

logy

main tenance

Lo
p-free
Lo

w consumption

f

memory , bandwidth

Scalable

to large no de p

pulations
Lo

calized eect

f

link break age

Minimal
v

erhead for data transmission

Rapid

con v ergence

and

... Multicast

SLIDE 3 P erkins, Ro y er 3 Sun, UCSB A OD V: Ad-Ho c On-Demand Distance V ector Routing

Quic

k lo

p-free

con v ergence

Route

creation

n

demand , lo calizing the eect

f

top

logy

c hanges, and mini- mizing con trol trac.

Distance

V ector, using Destination Sequence n um b ers for route up dates (on b

th

forw ard and rev erse paths)

T

riggered up dates and minimal latency for route replies

Reduced

bandwidth utilization

t

w

-dim'l

metric: <seq#, hop-coun t>

Enables

future aggregation computations

SLIDE 4 P erkins, Ro y er 4 Sun, UCSB A OD V Unicast Route Disco v ery RREQ (r

ute

r e que st) is broadcast

Rev

erse path is set up along the w a y

RREQ

message con tains < bcast id; dest ip; dest seq no; sr c ip; sr c seq no; hop count > RREP (r

ute

r eply) is unicast bac k

F

rom destination if necessary

F

rom in termediate no de if that no de has a recen t route

SLIDE 5 P erkins, Ro y er 5 Sun, UCSB Route Request (RREQ) Message F

rmat

0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 1 2 3 Type Broadcast ID Destination IP address Destination Sequence Number Source IP Address Source Sequence Number Reserved Hop Count

Source sequence n um b er helps set up short-live d rev erse route Destination sequence # is the last known for the requested destination (or, zero) Hop Coun t incremen ted b y ev ery in termediate no de

SLIDE 6 P erkins, Ro y er 6 Sun, UCSB Route Reply (RREP) Message F

rmat

0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 1 2 3 Type Destination IP address Destination Sequence Number Reserved Hop Count L Lifetime

Lifetime con trols ho w long the remains v alid at an in termediate no de after it is no longer active Hop Coun t incremen ted b y ev ery in termediate no de If broadcast with TTL=1, serv es as a hel lo message

SLIDE 7 P erkins, Ro y er 7 Sun, UCSB Link Break age

No

des remem b er activ e routes

Next

hop breaks ! neigh b

rs

using that route are notied

Notication

is a RREP with: { metric = 1 { dest seqno = previous + 1 and is sen t to eac h activ e neigh b

r

SLIDE 8 P erkins, Ro y er 8 Sun, UCSB A OD V Multicast Route Disco v ery Message t yp es:

RREQ,

with new ags `J' (Join) and `R' (R ep air)

RREP
MINV

Multicast routes ha v e a destination sequence n um b er and m ultiple next hops

Multicast

Group Leader extension for RREQ, RREP

SLIDE 9 P erkins, Ro y er 9 Sun, UCSB Multicast In v alidate Message F

rmat

0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 1 2 3 Type Destination IP address Destination Sequence Number Reserved Hop Count Source IP Address Source Sequence Number

A prosp ectiv e m ulticast group mem b er

nly

needs

ne

link to the m ulticast distri- bution tree, but it ma y receiv e m ultiple RREP messages. The MINV message prunes all the extra branc hes from the m ulticast tree. In termediate no des that are not part

f

the m ulticast group, that receiv e MINV

n

their

nly
utgoing

link, prune themselv es from the tree.

SLIDE 10 P erkins, Ro y er 10 Sun, UCSB T ree Main tenance

Multicast

group leader main tains group sequence n um b er

Pruning

(if no de lea v es tree) { leaf no des send MINV { in termediate no des remain Multicast group leader broadcasts GR OUP HELLO p erio dically , con taining the m ulticast group address, sequence n um b er, and group leader's address.

SLIDE 11 P erkins, Ro y er 11 Sun, UCSB Link Break age No des remem b er m ulticast tree branc hes No de further from m ulticast group leader initiates link repair Only no des whic h are closer to group leader can send RREP No de initiating repair selects new branc h, sends MINV No resp

nse

after RREQ RETRIES means tree is partitioned Initiating no de b ecomes new group leader, issues Group Hello

SLIDE 12 P erkins, Ro y er 12 Sun, UCSB Merging Disconnected T rees If a no de hears Group Hello from t w

group

leaders, it can repair the m ulticast tree

Sends

RREQ with `R' (r ep air) ag set to group leader

f

its partition

Only

group leader can resp

nd

to RREQ with R ag set

Group

leader sends RREQ with `J' (Join) ag set to

ther

group leader

Other

group leader sends RREP to no de

Group

Leader with smaller IP address b ecomes new group leader

New

Group Leader broadcasts Group Hello with new group leader information

SLIDE 13 P erkins, Ro y er 13 Sun, UCSB Ad-ho c Net w

rking

Example

MH MH MH MH MH MH MH MH MH MH MH MH MH MH MH MH MH MH 1 2 3 4 5 6 7 8 1

Supp

se

M H 1 mo v es a w a y from M H 2 to w ards M H 7 , and has activ e sessions with M H 3 and M H 6 . The follo wing actions

ccur:
M

H 2 notices that its link to M H 1 is brok en

M

H 2 c hec ks its routing table, and nds that its link to M H 1 w as activ ely in use b y M H 3 and M H 4 .

SLIDE 14 P erkins, Ro y er 14 Sun, UCSB

M

H 2 unicasts an 1-metric route up date, with an incremen ted destination sequence n um b er, to M H 3 and M H 4 . M H 3 ma y subsequen tly issue a new route request for M H 1 .

M

H 4 also notes that its route to M H 1 w as activ ely in use, and forw ards the 1-metric route up date to M H 6 .

The

1-metric route up date for M H 1 ma y also b e included in the next hel lo message issued b y M H 2

M

H 6 ma y subsequen tly issue a new route request for M H 1

An

y subsequen t route request for M H 1 whic h is satised b y a route reply through M H 2 ma y cause M H 2 to up date its route table Destination sequencing main tains nice prop erties

f

lo

p-freeness,

and eliminates Bellman-F

rd

"coun ting to innit y" problem.

SLIDE 15 P erkins, Ro y er 15 Sun, UCSB Repairing Multicast T ree Breaks

1 2 3 4 5 6 7 8 9 10 Group Leader

No de 4 detects link break age, initiates group repair Only no des in subtree con taining group leader can issue RREP After RREQ RETRIES, no de 4 broadcasts GR OUP HELLO message as a new leader