Transcript Ad hoc On-demand Distance Vector Routing (AODVv6)

Mobile IPv6 Ad hoc Gateway with
Handover Optimization
指導老師：黃培壝 老師
學生：藍成浩
Outline
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INTRODUCTION
NETWORK REQUIREMENTS
Mobile IPv6 Infrastructure
Ad hoc On-demand Distance Vector Routing (AODVv6)
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MOBILE IPV6 AD HOC GATEWAY
System Architecture
Mobile IPv6 Extensions
AODVv6 Extensions
Gateway Discovery
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HANDOVER OPTIMIZATION
EXPERIMENTS AND RESULTS
CONCLUSION AND FUTURE WORK
Introduction
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Future wireless networks will be available in every
mobile environment, especially in vehicles like busses,
cars, trains, and airplanes.
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These networks will provide wireless access to the
Internet so that mobile users are able to use IP-based
networks for exchanging data or downloading emails.
Introduction
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Such networks use ad hoc communication via
multihop ad hoc nodes.
MN
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MN
Hence, future mobile devices will have a combination
of multiple wireless interfaces and multihop ad hoc
support.
Introduction
One mobile scenario in the future is a wireless ad hoc
network in a train which supports wireless Internet access for
all mobile ad hoc users in every cabin.
Internet network
Mobile IPv6 Ad hoc Gateway
Mobile users
Introduction
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For this mobility scenario the gateway has to be mobile
to support vertical handovers between different bearer
systems and it has to provide horizontal handovers.
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Vertical handovers should be forced when the WLAN
link quality is not sufficient or the network congestion
decreases the throughput.
Introduction
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Mobile IPv6 provides handovers between different
bearer systems and allows transparent mobility support
in heterogeneous network environments.
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It uses so-called movement detection to detect new
access networks and exchanges binding updates (BU)
between the mobile node and the Home Agent.
Introduction
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For high velocities this movement detection is not
efficient and leads to high packet loss.
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Hence, in this study an optimization for vertical
handovers between different bearer systems .
Introduction
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This paper describes the advantages of IPv6 mobility ,
especially the integration of Mobile IPv6 together with
the ad hoc routing protocol AODVv6
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The vertical handover optimization is described in this
paper which is based on a proactive handover decision
using the link quality of the WLAN access point to
decide when a handover has to be forced.
Mobile IPv6 Infrastructure
Mobile IPv6 Ad hoc Gateway
Mobile IPv6 Infrastructure
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The Mobile IPv6 infrastructure that is shown in Fig.1
provides access to a WLAN system and a cellular
network.
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Therefore, a WLAN access point (802.11b) is attached
via Access Router (AR) with the HA and provides fully
IPv6 access to the MN.
Mobile IPv6 Infrastructure
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GPRS/UMTS where the infrastructure of the mobile
operator is mainly based on IPv4.
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Tunnelling mechanisms
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Open VPN was used in this study to tunnel the IPv6
traffic between the MN and the HA through the IPv4
network of the mobile operator transparently.
Ad hoc On-demand Distance Vector
Routing (AODVv6)
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Reactive routing protocol.
Route discovery
Ad hoc On-demand Distance Vector
Routing (AODVv6)
Route discovery
Ad hoc On-demand Distance Vector
Routing (AODVv6)
Route discovery
Ad hoc On-demand Distance Vector
Routing (AODVv6)
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Route maintenance : hello message 、 RERR
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A route error (RERR) message is sent by intermediate
nodes when a route is not valid anymore.
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After the source node receives a RERR the node starts
the route discovery again to find a valid route to the
destination.
System Architecture
System Architecture
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The gateway contains the Mobile IP stack that is
required to implement global mobility of the gateway .
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To integrate the ad hoc network the gateway also
contains the AODVv6 stack to attach the ad hoc
network to the mobile gateway.
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At last the system architecture also contains the
handover optimization to reduce the packet loss during
handovers.
Mobile IPv6 Extensions
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From the Mobile IP point of view the MN is the endpoint
of an active communication link that means that the MN
does not include any rerouting options for attached
networks.
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Therefore, it is required to extend the routing behaviour
of the MN.
Mobile IPv6 Extensions
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The kernel of the MN has to be extended to retransmit
data packets from/to the attached ad hoc network and
to receive the agent advertisements simultaneously.
Hence, the forwarding flag at the default MN’s interface
has to be activated and the accept_rf flag has to be
adapted to provide the gateway support.
Mobile IPv6 Extensions
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Moreover, the Home Agent does not maintain any
route to the ad hoc network .
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It is also required to extend the Home Agent functions
to support routing information of the attached ad hoc
network after each binding update.
AODVv6 Extensions
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The AODVv6 implementation which was used for this
study only provides local reachability.
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However, the integration of an attached ad hoc network
requires the support of global routable IPv6 addresses.
Gateway Discovery
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The AODVv6 implementation in [7] does not contain
any gateway discovery.
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This extension allows ad hoc nodes to find the mobile
gateway and to establish a connection to the Internet.
HANDOVER OPTIMIZATION
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The Mobile IPv6 Ad hoc Gateway supports an
optimization for vertical handovers to reduce packet
loss.
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This allows seamless mobility but it leads to packet
loss during the handover, because there is a short time
period where the previous access link is lost.
HANDOVER OPTIMIZATION
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Proactive handover decision .
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The proactive handover decision is based on receiving
link layer information to decide when a handover has to
be forced [9] and is part of the POLIMAND (Policy
based Mobile IPv6 Handover Decision) definition that
is described in [10].
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POLIMAND defines a threshold which indicates the link
quality so that a handover to a reliable bearer system
can be forced.
EXPERIMENTS AND RESULTS
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The Mobile IPv6 infrastructure consists of one HA that
is linked to a WLAN AP.
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The HA is connected to a CN that is also located within
the test bed and is connected to the Internet.
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A FR that is also located in the test bed is used to
attach the MN over a GPRS link to the test bed.
EXPERIMENTS AND RESULTS
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An OpenVPN tunnel at the FR is used for transparent
IPv6 connectivity between HA and MN.
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Mandrake Linux OS and Kernel 2.4.22.
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All Mobility Agents are equipped with a Linux IPv6
Router Advertisement Daemon [11] to broadcast the
required agent advertisements.
EXPERIMENTS AND RESULTS
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The handover of the mobile gateway are controlled by
an attenuator to reduce the link quality between the
WLAN AP and the WLAN card of the mobile gateway.
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To define the link layer threshold 5 iterations were
measured.
EXPERIMENTS AND RESULTS
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During the iteration 200 ICMP packets were sent
between the MN and the CN with a packet size of 64
bytes per second.
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To measure the mobility of the gateway 10 iterations
were taken to examine the packet loss during vertical
handovers between WLAN and GPRS.
EXPERIMENTS AND RESULTS
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The threshold for the link quality is derived from the
measured link quality of the WLAN access point when
the first packet is lost.
EXPERIMENTS AND RESULTS
EXPERIMENTS AND RESULTS
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The results of vertical handovers were measured during
an increasing number of handovers using a constant
advertisement period (1 advertisement per second)
EXPERIMENTS AND RESULTS
CONCLUSION AND FUTURE WORK
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The interconnection of ad hoc networks and the
Internet can be achieved by a mobile gateway that was
presented in this study.
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This gateway has to be mobile to provide mobility
support of entire ad hoc networks that will be located in
several vehicles in the future.
CONCLUSION AND FUTURE WORK
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Fulfil the QoS requirements in mobile ad hoc network.