Transcript Autoconfiguration Technologies in IPv6 Mobile Ad Hoc Networks

APAN2003
Autoconfiguration Technologies
in IPv6 Mobile Ad Hoc Networks
Jaehoon Jeong, ETRI
[email protected]
http://www.adhoc.6ants.net/~paul
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Contents








Introduction
Unicast Address Autoconfiguration
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.


There is no network administrator.


In MANET, there are many points to consider unlike the
Internet.
The current Internet services, such as address
autoconfigation 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
MANET
Autoconfiguration
Multicast DNS

Service Discovery
Unicast Address Autoconfiguration
Multicast Address Allocation
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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
through DAD.


A arbitrary address is selected.
The uniqueness of the address is verified though Duplicate
Address 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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Example of Strong DAD
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
MAC & IPv6 Address of Host C
 MAC Address – a9:bb:cc:dd:ee:ff
 IPv6 Address - fec0:0:0:ffff:abbb:ccff:fedd:eeff
Host C
Random Number
Host B
Host A
NS message
NA message
Router
Wireless Link
Where NS : Neighbor Solicitation,
NA : Neighbor Advertisement
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Procedure of Strong DAD
Generation of 32-bit Random Number
and 64-bit Random Number
Generation of Temporary address with
MANET_INIT_PREFIX and 32-bit Number
MANET_INIT_PREFIX
 fec0:0:0:ffff::/96
Generation of Tentative address with
MANET_PREFIX and 64-bit Number
MANET_PREFIX
fec0:0:0:ffff::/64
This iteration is
performed by
predefined
retry-number.
Transmission of Extended NS message
Was any extended
NA message received
from any other node?
YES
Generation of 64-bit
Random Number
NO
Reconfiguration of
Unicast address in NIC
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Problem of Strong DAD - 1/2
IP address = a
A
F
B
C
E
D
G
H
K
IP address = a
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Problem of Strong DAD – 2/2
IP address = a
A
F
B
C
E
D
G
H
K
IP 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.


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.


MAC address cannot be embedded in the IP address.
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


Random Number


When MAC address of an interface is guaranteed to be unique.
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
Routing table at node D
Dest
Next
Hop
IP_B
IP_B
IP_C
IP_E
IP_A
IP_B
IP_E
IP_E
A
B
C
E
D
Link state packet transmitted by D
From
To
Cost
IP_D
IP_E
2
IP_D
IP_B
10
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Link State Routing
with Weak DAD
Routing table at node D
Dest
Dest
Key
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
A
B
C
E
Link state packet transmitted by D
From
From
Key
To
To
Key
Cost
IP_D
K_D
IP_E
K_E
2
IP_D
K_D
IP_B
K_B
10
D
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Resolution of Address Conflict
by Weak DAD
(IP address, Key) = (a, K_A)
A
F
B
C
E
D
G
H
Duplication
Advertisement
K
(IP address, Key) = (a, K_K)
E detects the duplication
of address a with key
information
(IP address, Key) = (b, K_K)
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Hybid DAD

Hybid DAD


Combination of Strong DAD and (Enhanced) Weak DAD
 Strong DAD detects duplicate address within a single
connected partition.
 Weak DAD processes the address conflict by MANET’s
partition 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
large 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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Multicast Address Allocation
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Multicast Address Allocation

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).
64-bit
(a)
Network prefix
8-bit 8-bit
(b)
64-bit
FF
Interface ID
16-bit
64-bit
reserved
Interface ID
4-bit
0 A P T
Flags
32-bit
Group ID
4-bit
0 1 0 1
Scope
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Procedure of Multicast Address
Allocation
Request of
Multicast Address Allocation
Generation of Unused Group ID
Generation of a Multicast Address
Delivery of the Multicast Address
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Service of Multicast Application
: Allocation of a unique Multicast Address for a new Session
B
C
A
E
A
B
1
2
4
Step
D
C
1
D
1
1
Unicast Address Autoconfiguration
2
Run of Video-conferencing Tool (e.g.,
SDR) and Creation of a new Session
-> Multicast Address Allocation
3
Advertisement of Session Information
4
MN A’s join to the new Session
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MN E’s join to the new Session
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Transmission of Video/Audio Data
by MN A
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Transmission of Video/Audio Data
by MN E
E
1
1
3
6
5
Action
7
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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 System
for 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)
Mobile Node A
ANS
Zone DB
Application
ANS
Responder
Mobile Node B
ANS
Zone DB
Application
ANS
Resolver
Application
Application
ANS
Resolver
ANS
Responder
DNS Query
DNS Response
Node
Process
ANS
Responder
ANS
Resolver
Database
UNIX Datagram Socket
ANS
Zone DB
Application
Application
Memory Read / Write
Wireless Link
Mobile Node C
DNS Message
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ANS System (2/2)
Application
ANS Resolver
ANS Responder
Main-Thread
ANS Cache
Main-Thread
ANS
Zone DB
Resolv-Thread
Timer-Thread
DUR-Thread
Process
Thread
Memeory Read / Write
Process
UNIX Datagram Socket
Thread
Memeory Read / Write
Cache
Internal Connection
Internal Connection
Database
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Name Service in ANS

Name Generation


Zone File Generation


generates a unique domain name based on the
network device identifier
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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Service Discovery based on
Multicast DNS
ANS Responder’s Zone File
$TTL 20
$ORIGIN ADHOC.
PAUL-1
IN
IPv6 Multicast Address
corresponding to Service Name
AAAA FEC0:0:0:FFFF:3656:78FF:FE9A:BCDE
8
;; 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.
FF
Flags
P=0, T=1
; Multicast Service : SERVICE-2
_SERVICE-2._UDP
IN SRV 0 1 4000 @.1.5.
Generation of
IPv6 Multicast
Address
4 4
DNS SRV Resource Record for
Multicast Service
Multicast Service Name
Parsing Function
MD5 Hash Function
Flags label & Scope label
128-bit Digest
16-bit IPv6 Site-local
Multicast Address Prefix
+
112
Group ID
Scope
5
Group ID=Low-order 112 bits of Digest
IPv6 Site-local Multicast Address
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Scenario of Service Discovery
MN-C
MN-A
MN-B
Request of
Server Information
DNS Query Message
for Service Information
DNS Query Message
is sent in Multicast
DNS Query Message
for Service Information
Receipt of
DNS Query Message
DNS Response Message
with Service Information
Receipt and Process
of DNS Query Message
related to
DNS SRV resource record
Gain of
Service Information
MN-C tries to connect to
the server on MN-A
or
MN-C joins the multicast group
related to MN-A
The server on MN-A accepts the
request of the connection from MN-C
or
The multicast group comprises
MN-A and MN-C
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Protocol Stack supporting
MANET Autoconfiguration
Unicast Address
Autoconfiguration
Multicast Address
Allocation
TCP/UDP
ICMPv6
IPv6
Network
Interface
Multicast
DNS
Service
Discovery
Application
Transport
MLD
Network
Link
Wireless Link
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Conclusion

MANET Autoconfiguration





Unicast Address Autoconfiguration
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”,
MobiHoc2002, June 2002.
[3] Charles E. Perkins et al., “IP Address Autoconfiguration for Ad Hoc Networks”, draftietf-manet-autoconf-01.txt, November 2001.
[4] Jaehoon Jeong and Jungsoo Park, “Autoconfiguration Technologies for IPv6 Multicast
Service 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-ietfipv6-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.
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