Transcript Ad hoc routing protocols

Ad Hoc 라우팅 표준(RFC3561)과
IPv6 적용기법
정재훈 (Jaehoon Paul Jeong)
한국전자통신연구원 표준연구센터
[email protected]
http://www.adhoc.6ants.net/
2003. 10. 23
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Contents


Introduction
Ad Hoc Unicast Routing Protocols


AODV (RFC 3561)





Demand-driven Routing Protocols
AODV Message Formats
IPv6 AODV
Autoconfiguration Technologies for IPv6 MANET
Summary
References
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Introduction (1/2)

Categories of Wireless Networks

Infrastructured Network


Infrastructureless Network


Cellular Network, Wireless LAN (WLAN)
Ad Hoc Network
Ad Hoc Network



Temporary network composed of mobile nodes without
preexisting communication infrastructure, such as Access
Point (AP) and Base Station (BS).
Each node plays the role of router for multi-hop routing.
Application

War-field communication, Emergency recovery, Homenetworking, Video-conferencing etc.
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Mobile Ad Hoc Networks
Internet
WLAN
Cellular
Mobile Ad Hoc Networks
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Introduction (2/2)

Issues in MANET






Ad Hoc Unicast Routing
Ad Hoc Multicast/Broadcast Routing
Power Saving
Global Connectivity for MANET
Addressing & DNS
Automatic Support of Networking Facility in
MANET

Autoconfiguration Technology
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Ad Hoc Unicast Routing Protocols
Ad Hoc routing protocols
Table-driven
(Proactive)
DSDV OLSR TBRPF AODV
CGSR
Demand-driven
(Reactive)
DSR
Hybrid
LMR
ABR
TORA
SSR
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ZRP
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Demand-driven Routing Protocols

Characteristics

Creation of routes only when desired by the source node


Route Discovery Process is completed




Until the destination becomes inaccessible along every path
from the source
Until the route is no longer desired
Criterion of Classification of Routing Protocols


Once a route is found
When all possible route permutations have been examined
Maintenance of a Route


By Route Discovery Process
Method by which route finding is performed
Examples

AODV, DSR, LMR, TORA, ABR, SSR
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AODV (RFC 3561)
Ad hoc On-Demand Distance Vector
C. Perkins, E. Belding-Royer and S. Das,
July 2003.
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Contents





Overview of AODV
Route Discovery
Route Maintenance
Optimizations
AODV Message Formats
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Overview of AODV (1/2)

AODV is improved DSDV algorithm



Reactive or On-demand
Provides unicast and multicast communication
(MAODV)
AODV doesn’t maintain a complete list of routes
as in DSDV algorithm.


Nodes that are not on a selected path don’t maintain
routing information or participate in routing table
exchanges.
Loop-free

AODV utilizes destination sequence numbers to ensure
all routes are loop-free.
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Overview of AODV (2/2)

Route Discovery process

When does it happen?


When source node doesn’t already have
a valid route to a destination
Route Discovery


It broadcasts a route request (RREQ) packet to its
neighbors.
Neighbors forward the request to their neighbors, and so
on until either the destination or
an intermediate node with a “fresh enough” route
to the destination is located.
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Route Discovery (1/10)
B
S
A
C
D
1. Node S needs a route to D in order to send data
packets to D
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Route Discovery (2/10)
B
S
A
C
D
1. Node S needs a route to D in order to send data
packet to D
2. Creates a Route Request (RREQ)
Enters D’s IP addr, seq#,
S’s IP addr, seq#
hopcount (=0)
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Route Discovery (3/10)
B
RREQ
S
A
C
D
2. Creates a Route Request (RREQ)
Enters D’s IP addr, seq#,
S’s IP addr, seq#
hopcount (=0)
3. Node S broadcasts RREQ to neighbors
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Route Discovery (4/10)
B
RREQ
S
A
C
D
4. Node A receives RREQ

Makes reverse route entry for S
dest = S, nexthop = S, hopcnt = 1
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Route Discovery (5/10)
B
RREQ
S
A
C
D
4. Node A receives RREQ


Makes reverse route entry for S
dest = S, nexthop = S, hopcnt = 1
It has no route to D, so it rebroadcasts RREQ
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Route Discovery (6/10)
B
RREQ
S
A
C
D
5. Node C receives RREQ


Makes reverse route entry for S
dest = S, nexthop = A, hopcnt = 2
It has a route to D, and
the seq# for route for D is >=D’s seq# in RREQ
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Route Discovery (7/10)
B
S
A
RREP
C
D
6. Node C sends RREP


C creates a Route Reply (RREP)
Enters D’s IP addr, seq #
S’s IP addr, hopcount to D (=1)
Lifetime
Unicasts RREP towards A
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Route Discovery (8/10)
B
RREP
S
A
RREP
C
D
7. Node A receives RREP


Makes forward route entry to D
dest = D, nexthop = C, hopcount = 2, Lifetime
Unicasts RREP to S
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Route Discovery (9/10)
B
RREP
S
A
C
D
8. Node S receives RREP

Makes forward route entry to D
dest = D, nexthop = C, hopcount = 3, Lifetime
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Route Discovery (10/10)
B
S
A
C
D
9. Node S sends data packets on route to D
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Route Maintenance (1/5)
B
S
A
RERR
C
D
1. Link between C and D breaks down

C can perform local repair for the route to D
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Route Maintenance (2/5)
B
S
A
RERR
C
D
1. Link between C and D breaks down

C can perform local repair for the route to D
2. Node C invalidates route to D in route table
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Route Maintenance (3/5)
B
S
A
RERR
C
D
3. Node C creates Route Error (RERR) message


C creates a Route Error (RERR)
Enters DestCount (=1), D’s IP addr, seq #
Lists all destinations which are now unreachable


“DestCount” field indicates the number of unreachable
destinations included in the RERR message.
Sends to upstream neighbors in precursor list
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Route Maintenance (4/5)
B
RERR
S
A
RERR
C
D
4. Node A receives RERR


Checks whether C is its next hop on route to D
Deletes route to D
or invalidates the route to D according to N flag
(No delete flag)


When N flag is set, A does not send RERR to S and may reinitiate
route discovery for D.
Forwards RERR to S
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Route Maintenance (5/5)
B
RERR
S
A
C
D
5. Node S receives RERR



Checks whether A is its next hop on route to D
Deletes route to D
Rediscovers route if still needed
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Optimizations (1/2)

Expanding Ring Search



It prevents flooding of network during route
discovery
Control Time To Live (TTL) of RREQ to search
incrementally larger areas of network
Advantage


Less overhead when successful
Disadvantage

Longer delay if route not found immediately
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Optimizations (2/2)

Local Repair

It repairs breaks in active routes locally instead of
notifying source.


Advantage


If the first repair attempt is unsuccessful, it sends RERR to
source.
Link repair with less overhead, delay and packet loss.
Disadvantage

Longer delay and greater packet loss when unsuccessful
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AODV Message Formats
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Route Request (RREQ)
Message Format
0
1
2
3
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
Type
|J|R|G|D|U|
Reserved
|
Hop Count
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
RREQ ID
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
Destination IP Address
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
Destination Sequence Number
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
Originator IP Address
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
Originator Sequence Number
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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Route Reply (RREP)
Message Format
0
1
2
3
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
Type
|R|A|
Reserved
| Prefix Sz |
Hop Count
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
Destination IP address
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
Destination Sequence Number
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
Originator IP Address
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
Lifetime
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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Route Error (RERR)
Message Format
0
1
2
3
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
Type
|N|
Reserved
|
DestCount
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
Unreachable Destination IP Address (1)
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
Unreachable Destination Sequence Number (1)
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-|
|
Additional Unreachable Destination IP Addresses (if needed)
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
Additional Unreachable Destination Sequence Numbers (if needed)
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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Route Reply Acknowledgement
(RREP-ACK) Message Format
0
1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
Type
|
Reserved
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

RREP-ACK message MUST be sent in response to
a RREP message with the ‘A’ bit set.

This is typically done when there is danger of unidirectional
links preventing the completion of
a Route Discovery cycle.
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IPv6 AODV
C. Perkins, E. Belding-Royer and S. Das,
draft-perkins-manet-aodv6-01,
November 2001.
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AODV for IPv6 Operation

Message Handling

The handling of IPv6 AODV for IPv6 AODV messages is
analogous to IPv4 AODV.


ICMP Processing


AODV messages have the formats appropriate for use with 128bit IPv6 addresses.
Whenever IPv4 AODV specifies use of ICMP, the operation
for IPv6 uses ICMPv6.
Configuration Parameters

IPv4 and IPv6 AODVs use the same parameters.
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Autoconfiguration Technologies
for IPv6 MANET
Reference Paper:
http://www.adhoc.6ants.net/publications/
international-conference/icoin2004-jaehoon.pdf
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Autoconfiguration?

What is Autoconfiguration?


Issues of IETF Zeroconf Working Group





The technology that allows IP-enabled devices be able to
communicate one another in infrastructureless environment.
Unicast Address Autoconfiguration
Multicast Address Allocation
Name Resolution (DNS)
Service Discovery
Why is Autoconfiguration needed in MANET?

To provide the quick and easy configuration related to the
networking in MANET with dynamic topology.
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Autoconfiguration Technology for
IPv6 MANET

Unicast Address Autoconfiguration


Automatic configuration of a unique IPv6 address within
MANET
Multicast Address Allocation

Allocation of a unique multicast address for the application
which needs a new multicast address
Multicast DNS


Translation between name and
IPv6 address
Service Discovery

Discovery of the necessary service
제1회 IPv6 표준화워크샵 및 표준설명회
Autoconfiguration
Technology
for IPv6 MANET
Multicast DNS

Service Discovery
Unicast Address Autoconfiguration
Multicast Address Allocation
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Summary

AODV




It is a Reactive/On-demand Ad Hoc routing protocol.
 Route Discovery cycle
Sequence numbers are used for route freshness and loop
prevention.
It maintains only active routes.
Optimizations can be used to reduce overhead and
increase scalability.

IPv6 AODV

Autoconfiguration Technologies for IPv6 MANET
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References
[1] C. Perkins, E. Belding-Royer and S. Das,
“Ad hoc On-Demand Distance Vector (AODV) Routing”,
RFC 3561, July 2003.
[2] C. Perkins, E. Belding-Royer and S. Das,
“Ad Hoc On Demand Distance Vector (AODV) Routing for IP
version 6”, draft-perkins-manet-aodv6-01, November 2001.
[3] Auto-Networking Technologies for IPv6 MANET,
http://www.adhoc.6ants.net/publications/internationalconference/icoin2004-jaehoon.pdf
[4] ETRI Ad Hoc Project,
http://www.adhoc.6ants.net/
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