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MANET Auto-Configuration

Jaehoon Jeong, ETRIpaul@etri.re.kr

http://www.adhoc.6ants.net/~paul

KRnet2003KRnet2003

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Contents

Introduction Unicast Address Autoconfiguration IPv6 Multicast Address Allocation Multicast DNS Service Discovery Protocol Stack supporting MANET

Autoconfiguration Conclusion References

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Introduction

Mobile Ad Hoc Network (MANET) MANET has dynamically changing network topology.

MANET partition and mergence may happen. In MANET, there are many points to consider unlike the Internet.

There is no network administrator. The current Internet services, such as address autoconfi

gation and DNS, are difficult to adopt.

So, Auto-configuration is necessary in MANET!!

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MANET Auto-configuration

Unicast Address Autoconfiguration Multicast Address Allocation Multicast DNS Service Discovery

MANETAutoconfiguration

Mu

ltic

as

t D

NS

Se

rvic

e D

isc

ov

ery

Multicast Address Allocation

Unicast Address Autoconfiguration

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Unicast Address Autoconfiguration

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Introduction Configuration of Unicast Address in Network Interface

Precedent step for IP networking Methods of IP address configuration in network interface

Manual configuration Automatic configuration

Consideration of IP address configuration A unique address should be assigned. Automatic configuration is needed for user’s convenience.

Addressing in MANET Each mobile node is necessary to autoconfigure its IP address t

hrough DAD. A arbitrary address is selected. The uniqueness of the address is verified though Duplicate Addre

ss Detection (DAD).

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Strong DAD

Definition Ai(t) : Address assigned to node i at time t. For each address a != undefined,

Sa(t) = {j | Aj(t) = a}.

Condition of Strong DAD Within a finite bounded time interval after t,

at least one node in Sa(t) will detect that |Sa(t)| > 1.

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Host A

Router

Host B

Wireless Link

NS message NA message

Host C

Where NS : Neighbor Solicitation, NA : Neighbor Advertisement

MAC & IPv6 Address of Host C MAC Address – a9:bb:cc:dd:ee:ff IPv6 Address - fec0:0:0:ffff:abbb:ccff:fedd:eeff

1st Try of Host A MAC Address - a9:bb:cc:dd:ee:ff IPv6 Address - fec0:0:0:ffff:abbb:ccff:fedd:eeff

MANET Prefix

EUI-64

2nd Try of Host A 64-bit Random Number – 1111:2222:3333:4444 IPv6 Address - fec0:0:0:ffff:1111:2222:3333:4444

Random Number

Example of Strong DAD

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Generation of Tentative address with MANET_PREFIX and 64-bit Number

Generation of 64-bitRandom Number

Was any extended NA message received from any other node?

YES NO

Reconfiguration of Unicast address in NIC

Transmission of Extended NS message

MANET_INIT_PREFIX

fec0:0:0:ffff::/96

MANET_PREFIX

fec0:0:0:ffff::/64

Generation of 32-bit Random Numberand 64-bit Random Number

Generation of Temporary address withMANET_INIT_PREFIX and 32-bit Number

Procedure of Strong DAD

This iteration is This iteration is performed by performed by

predefined predefined retry-number.retry-number.

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Problem of Strong DAD - 1/2

AA

CC

EE

DD

BB

FF

GG

HH

KK

IP address = aIP address = a

IP address = aIP address = a

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Problem of Strong DAD – 2/2

AA

CC

EE

DD

BB

FF

GG

HH

KK

IP address = aIP address = a

IP address = aIP address = a

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Conclusion for Strong DAD

Simple Observation If partitions can occur for unbounded

intervals of time, then strong DAD is impossible.

Limitation of Charles E. Perkins’s DAD When partitions merge, addresses of all

nodes must be checked for duplicates. This DAD does not indicate how merging of

partitions should be detected. This does not suggest how the congestion

caused by DAD messages may be reduced.

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Weak DAD

Requirements Correct Delivery

Packets meant for one node must not be routed to another node, even if the two nodes have chosen the same address.

Relaxed DAD It does not require detection of all duplicate

addresses. The duplication of addresses can not be

detected in partitioned networks.

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Definition

Assumption A packet sent by node X at time t to

destination address a be delivered to node Y that has chosen address a.

Condition After time t, packets from node X with

destination address a are not delivered to any node other than node Y.

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Design Goals Address size cannot be made arbitrarily large.

MAC address cannot be embedded in the IP address.

IP header format should not be modified. It is wanted to add new options to the IP header.

Contents of routing-related control packets may be modified to include information pertinent to DAD. E.g., Link state updates, Route request / reply.

No assumptions should be made about protocol layers above the network layer.

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Main Idea Key is used for the purpose of detecting

duplicate IP addresses. The key is not embedded in the IP address itself.

Generation of Key MAC Address

When MAC address of an interface is guaranteed to be unique.

Random Number A sufficiently large number of bits of making the

probability of key conflict acceptably small Number derived from some other information

E.g., Manufacture’s name and device serial number

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Link State Routing with Strong DAD

AA

CC

EE

DD

BB

Dest Next Hop

IP_B IP_B

IP_C IP_E

IP_A IP_B

IP_E IP_E

Routing table at node DRouting table at node D

From To Cost

IP_D IP_E 2

IP_D IP_B 10

Link state packet transmitted by DLink state packet transmitted by D

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Link State Routing with Weak DAD

Dest DestKey

Next Hop

IP_B K_B IP_B

IP_C K_C IP_E

IP_A K_A IP_B

IP_E K_E IP_E

Routing table at node DRouting table at node D

From FromKey

To ToKey

Cost

IP_D K_D IP_E K_E 2

IP_D K_D IP_B K_B 10

Link state packet transmitted by DLink state packet transmitted by D

AA

CC

EE

DD

BB

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Resolution of Address Conflict by Weak DAD

AA

CC

EE

DD

BB

FF

GG

HH

KK

(IP address, Key) = (a, K_A)(IP address, Key) = (a, K_A)

(IP address, Key) = (a, K_K)(IP address, Key) = (a, K_K)

(IP address, Key) = (b, K_K)(IP address, Key) = (b, K_K)E detects the duplication E detects the duplication

of address of address aa with key with key information information

DuplicationDuplicationAdvertisementAdvertisement

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Hybid DAD Hybid DAD

Combination of Strong DAD and (Enhanced) Weak DAD Strong DAD detects duplicate address within a single conn

ected partition. Weak DAD processes the address conflict by MANET’s part

ition and mergence.

Hybrid DAD Scheme It may detect some duplicate addresses sooner than using

weak DAD alone. The use of weak DAD makes it robust to partitions and larg

e message delays in Strong DAD.

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Phases of Hybid DAD 1st Phase

By Strong DAD Time-based DAD

It is performed in the stage for IPv6 address to be configured in network interface.

2nd Phase By Weak DAD It is performed during the routing process.

Router discovery in reactive Ad Hoc routing protocols, such as DSR and AODV.

Routing information exchange in proactive Ad Hoc routing protocols, such as OLSR and TBRPF.

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Conclusion for Unicast Address Autoconfiguration

Requirements of Ad Hoc DAD Correct Delivery

Packets meant for one node must not be routed to another node, even if the two nodes have chosen the same address.

Relaxed DAD It does not require detection of all duplicate

addresses. The duplication of addresses can not be detected in

partitioned networks.

Guarantee of Upper-layer session Under the address change by DAD, the upper-layer

session, such as TCP session, should be guaranteed to continue.

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IPv6 Multicast Address Allocation

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IPv6 Multicast Address Allocation

Network prefix Interface ID

Interface IDFF Group ID

(a)

(b)

64-bit 64-bit

64-bit 32-bit8-bit

4-bit 4-bit

Flags Scope

0 A P T 0 1 0 1

8-bit

reserved

16-bit

Role It allocates a unique IPv6 multicast address to a session

without address allocation server.

Address Format IPv6 multicast (a) is generated on the basis of Interface ID

of IPv6 unicast address (b).

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Procedure of Multicast Address Allocation

Generation of Unused Group ID

Generation of a Multicast Address

Delivery of the Multicast Address

Request ofMulticast Address Allocation

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Service of Multicast Application: Allocation of a unique Multicast Address for a new Session

B C DEA

A B C D E

1

2 3

456

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1 1 1 1

Step

Action

1 Unicast Address Autoconfiguration

2 Run of Video-conferencing Tool (e.g., SDR) and Creation of a new Session

3 Advertisement of Session Information

4 MN A’s join to the new Session

5 MN E’s join to the new Session

6 Transmission of Video/Audio Data by MN A

7 Transmission of Video/Audio Data by MN E

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Multicast DNS

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Introduction

Name Service in MANET MANET has dynamic network topology

Current DNS can not be adopted in MANET! Because it needs a fixed and well-known name server

Idea of Name Service in MANET All the mobile nodes take part in name service

Every mobile node administers its own name information It responds to the other node’s DNS query related to its

domain name and IP address

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Related Work: Link-Local Multicast Name Resolution (LLMNR)

DNS service based on IP multicast in link-local scoped network

Each node performs the role of DNS name server for its own domain name.

LLMNR Sender LLMNR Responder

LLMNR query message (What is IPv6 address of “host.private.local”?) - It is sent in link-local multicast

LLMNR response message (IPv6 address of “host.private.local”) - It is sent in link-local unicast

Verification of LLMNR response - Does the value of the response conform to the addressing requirements? - Is hop-limit of IPv6 header 1?

If the result is valid, then the Sender caches and passes the response to the application that initiated DNS query.

else the Sender ignores the response and continues to wait for other responses.

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Ad Hoc Name Service Systemfor IPv6 MANET (ANS)

ANS provides Name Service in MANET

Architecture of ANS System ANS Responder

It performs the role of DNS Name Server ANS Resolver

It performs the role of DNS Resolver

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ANS System (1/2)

ANSResolver

ApplicationApplication

Process

Database

Node

Mobile Node A

UNIX Datagram Socket

ANSResponder

ANSZone DB

Memory Read / Write

ANSResolver

ApplicationApplication

Mobile Node B

ANSResponder

ANSZone DB

Wireless Link

ANSResolver

ApplicationApplication

ANSResponder

ANSZone DB

ANSResolver

ApplicationApplication

ANSResponder

ANSZone DB

Mobile Node C

ANSResponder

ANSResolver

ApplicationApplicationApplicationApplicationANS

Zone DB

DNS Query

DNS Response

DNS Message

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ANS System (2/2)

Main-Thread

DUR-Thread

ANSZone DB

ANS Responder

Process

Thread

Database

Memeory Read / Write

Internal Connection

UNIX Datagram Socket

Main-Thread

Resolv-ThreadTimer-Thread

ANS Cache

ANS Resolver

Process

Thread

Cache

Memeory Read / Write

Internal Connection

Application

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Name Service in ANS

Name Generation generates a unique domain name based on

the network device identifier

Zone File Generation generates ANS zone file with the unique

domain name and corresponding IPv6 address

Name Resolution performs the name-to-address translation

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Conclusion for Multicast DNS

ANS is a new name service scheme in MANET.

Name service of ANS Automatic name generation Automatic zone file generation Name-to-address translation

Future work ANS will be enhanced to provide secure name service.

Authentication of DNS response message through Pre-shared group key and IPsec ESP’s null-transform

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Service Discovery

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Service Discovery Definition

Discovery of the location (IP address, Transport-layer protocol, Port number) of server that provides some service.

Methods Multicast DNS based Service Discovery

Service discovery through Multicast DNS and DNS SRV

resource record, which indicates the location of server or the multicast address of the service

SLP based Service Discovery Service discovery through IETF Service Location

Protocol (SLP) RFC 2165, RFC 2608, RFC 3111

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Considerations for Service Discovery

Limitations of Existing Schemes Most of current schemes are concerned with

service location for the Internet. Such protocols have not taken into account the

mobility, packet loss issues and latency.

Considerations Some devices are small and have limited

computation, memory, and storage capability. They can only act as clients, not servers.

Power constraints Service discovery should not incur excessive

messaging over wireless interface.

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$TTL 20$ORIGIN ADHOC.PAUL-1 IN AAAA FEC0:0:0:FFFF:3656:78FF:FE9A:BCDE

;; DNS SRV Resource Records; Unicast Service : SERVICE-1_SERVICE-1._TCP IN SRV 0 1 3000 PAUL-1.ADHOC._SERVICE-1._UDP IN SRV 0 1 3000 PAUL-1.ADHOC.

; Multicast Service : SERVICE-2_SERVICE-2._UDP IN SRV 0 1 4000 @.1.5.

Service Discovery based on Multicast DNS

Group IDFF

FlagsP=0, T=1

Scope5

8 4 1124

Multicast Service Name

+

128-bit Digest

MD5 Hash Function

Group ID=Low-order 112 bits of Digest

DNS SRV Resource Record for Multicast Service

Flags label & Scope label

Parsing Function

16-bit IPv6 Site-localMulticast Address Prefix

IPv6 Site-local Multicast Address

ANS Responder’s Zone File

IPv6 Multicast Address corresponding to Service Name

Generation of IPv6 Multicast Address

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Scenario of Service Discovery

MN-C MN-B MN-A

DNS Query Messagefor Service Information

DNS Query Messageis sent in Multicast Receipt of

DNS Query Message

Request ofServer Information

Receipt and Processof DNS Query Message

related toDNS SRV resource recordDNS Response Message

with Service Information

Gain ofService Information

MN-C tries to connect to the server on MN-A

orMN-C joins the multicast group

related to MN-A

The server on MN-A accepts the request of the connection from MN-C

orThe multicast group comprises

MN-A and MN-C

DNS Query Messagefor Service Information

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Protocol Stack supporting

MANET Autoconfiguration

NetworkInterface

IPv6 MLDICMPv6

TCP/UDP

Wireless Link

Link

Network

Transport

ApplicationUnicast Address

AutoconfigurationMulticast Address

AllocationMulticast

DNSService

Discovery

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Conclusion MANET Autoconfiguration

Unicast Address Autoconfiguration IPv6 Multicast Address Allocation Multicast DNS Service Discovery

Autoconfiguration Technologies in MANET They can provide Ad Hoc users with auto-

networking. They should be default functions for the deployment

of MANET. Also, security in MANET is important issue and is

considered together in auto-networking in MANET.

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References[1] Jaehoon Jeong, Hyunwook Cha, Jungsoo Park and Hyoungjun Kim, “Ad Hoc IP Address

Autoconfiguration”, draft-jeong-adhoc-ip-addr-autoconf-00.txt, May 2003.[2] Nitin H. Vaidya, “Weak Duplicate Address Detection in Mobile Ad Hoc Networks”, Mobi

Hoc2002, June 2002.[3] Charles E. Perkins et al., “IP Address Autoconfiguration for Ad Hoc Networks”, draft-ietf

-manet-autoconf-01.txt, November 2001.[4] Jaehoon Jeong and Jungsoo Park, “Autoconfiguration Technologies for IPv6 Multicast S

ervice in Mobile Ad-hoc Networks”, 10th IEEE International Conference on Networks, August 2002.

[5] Jung-Soo Park and Myung-Ki Shin, “Link Scoped IPv6 Multicast Addresses”, draft-ietf-ipv6-link-scoped-mcast-02.txt, July 2002.

[6] Jaehoon Jeong, Jungsoo Park, Hyoungjun Kim and Kishik Park, “Name Service in IPv6 Mobile Ad-hoc Network”, ICOIN2003, February 2003.

[7] Gulbrandsen, P. Vixie and L. Esibov, “A DNS RR for specifying the location of services (DNS SRV)”, RFC2782, February 2000.

[8] Jaehoon Jeong, Jungsoo Park, and Hyoungjun Kim, “Service Discovery based on Multicast DNS in IPv6 Mobile Ad-hoc Networks”, VTC2003 Spring, April 2003.