Mobile Internet Protocol

Mobile Internet Protocol

Internet Engineering Task Force (IETF) standard communications protocol that is designed to allow mobile device users to move from one network to another while maintaining a permanent IP address. Mobile IPv4 is described in IETF RFC 3344 (Obsoleting both RFC 3220 and RFC 2002), and updates are added in IETF RFC 4721. Mobile IPv6 is described in IETF RFC 3775

Course Name : Networking Level(UG/PG): UG Author : Phani Swathi Chitta Mentor : Aruna Adil

*The contents in this ppt are licensed under Creative Commons Attribution-NonCommercial-ShareAlike 2.5 India license

Learning ObjectivesAfter interacting with this Learning Object, the learner will be able to:• Explain how Mobile Internet Protocol (MIP) works

Definitions of the components/Keywords:

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1 • Although the Internet offers access to information sources worldwide, typically we do not expect to benefit from that access until we arrive at some familiar point--whether home, office, or school. However, the increasing variety of wireless devices offering IP connectivity, such as PDA’s, hand held, and digital cellular phones, is beginning to change our perceptions of the Internet.

• Having the Internet available to us as we move, will give us the tools to build new computing environments wherever we go. However, there are still some technical obstacles that must be overcome before mobile networking can become widespread. The most fundamental is the way the Internet Protocol, the protocol that connects the networks of today's Internet, routes packets to their destinations according to IP addresses. These addresses are associated with a fixed network location much as a non mobile phone number is associated with a physical jack in a wall. When the packet's destination is a mobile node, this means that each new point of attachment made by the node is associated with a new network number and, hence, a new IP address, making transparent mobility impossible. Mobile IP (RFC 3344) is a standard proposed to solve this problem


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1 • Mobile IP : A standard that allows users with mobile devices whose IP addresses are associated with one network to stay connected when moving to a network with a different IP address. When a user leaves the network with which his device is associated (home network) and enters the domain of a foreign network, the foreign network uses the Mobile IP protocol to inform the home network of a care-of address to which all packets for the user's device should be sent.Mobile IP is most often found in wireless WAN environments where users need to carry their mobile devices across multiple LANs with different IP addresses.

• We propose to simulate the Mobile IP protocol using Java as implementation language.

• How Mobile IP works: Mobile IP can be thought of as a cooperation of three major subsystems. First, there is a discovery mechanism defined so that mobile computers can determine their new attachment points (new I P addresses) as they move from place to place within the Internet. Second, once the mobile computer knows the IP address at its new attachment point, it registers with an agent representing it at its home network. Lastly, mobile IP defines simple mechanisms to deliver data-grams to the mobile node when it is away from its home network.


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1Entities & Terminologies

The following defines several entities and terms needed to understand Mobile IP as defined in RFC 3344:

Mobile Node (MN): It is an end system that can change its point of attachment to the Internet using Mobile IP .It keeps its IP address and can communicate with any other system in the Internet.

Correspondent Node (CN): The end system with which the MN communicates is called CN. It can be a fixed or a mobile node.

Home network: It is the subnet to which the MN belongs.

Foreign network: The current subnet that the MN visits and is not the home network.

Foreign Agent (FA): It provides several services to the MN during its visit. The FA can have the COA acting as the tunnel endpoint and forwards packets to the MN. It is not necessary to have a FA. It is typically implemented on the router for the subnet the MN attaches to.

Care-of-address (COA): It defines the current location of the MN from an IP point of view. All packets sent to the MN are delivered to the COA and not directly to the MN. Packet delivery is done using a tunnel and COA marks the tunnel endpoint. There are two possibilities for the location of the COA.


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1 Foreign agent COA: The COA is the IP address of the FA. The FA acts as the tunnel endpoint and forwards packets to the MN. Many MN using the FA can share this COA.

Co-located COA: The COA is co-located if the MN temporarily acquires an additional IP address using DHCP which acts as the COA. This address is topologically correct and the tunnel endpoint is at the MN.

Home agent (HA): The HA provides several services to the MN and is located in the home network. The tunnel for the packets starts at the HA. It maintains a location registry i.e. the current COA informs it of the MN’s location. It can be implemented on the router that is responsible for the home network or on any node in the subnet.

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1 Data Packet:

Version(VER): Defines the version of IP protocol.Currently the version is 4.

Header length(HLEN): Defines the total length of the datagram header in 4-byte words.

Differentiated Services(DS): Defines the type of service--Normal , Minimize Cost,Maximize reliability,Maximize throughput,Minimize Delay.

Total length: Defines the total length(header plus data) of the IP Datagram in bytes.

Identification: This field is used in fragmentation.It identifies a datagram originating from the source host.


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1 Flags: This field is also used in fragmentation.This is a three-bit field.The first bit is reserved.The second bit is called the do not fragment bit.The third bit is called the more fragment bit.

Fragmentation offset: This 13-bit field shows the relative position of this fragment with respect to the whole datagram.

Time to live(TTL): A datagram has a limited lifetime in its travel through an internet.This field is designed to hold a timestamp,which is decremented by each visited router.The datagram is discarded when the value becomes zero.

Protocol: This 8-bit field defines the higher-level protocol that uses the services of the IP layer.

Checksum: The error detection method used by most TCP/IP protocols is called the checksum.The checksum in the IP packet covers only the header,not the data.

Source address: The 32-bit field defines the IP address of the source.

Destination address: The 32-bit field defines the IP address of the destination.


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1 Request Packet:

Type: this field is set to 1 for registration requestS: this bit is used by MN to specify if it wants the HA to retain prior mobility bindingsB: this bit is used to indicate that an MN also wants to receive the broadcast packets which have been received by the HA in the home networkD: this bit is used to indicate that the MN takes care of the decapsulation at the tunnel endpoint since its using a co-located COAM: this bit denotes the use of minimal encapsulationG: this bit denotes the use of generic encapsulationr: this field is set to 0T: this field indicates reverse tunnelingx: this field is set to 0home address: this field gives the fixed IP address of the MN


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1 home agent: this field gives us the IP address of the HACOA: this field gives the address of the tunnel endpointIdentification: this field is generated by the MN to identify a request and match it with registration replies. Its used for protection against replay attacks of registrations.Extensions: this field atleast contains parameters for authentication.

Reply Packet:


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1 Type: this field is set to 3 for registration reply

Code: this field indicates the result of the registration request

lifetime: this field denotes the validity of the registration in seconds

home address: this field gives the fixed IP address of the MN

home agent: this field gives us the IP address of the HA

Identification: this field is generated by the MN to identify a request and match it with registration replies. Its used for protection against replay attacks of registrations.

Extensions: this field atleast contains parameters for authentication.


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1 Advertisement Packet:


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1type: is set to 16.

length: depends on the number of COAs provided with the messages.

sequence number: shows the total number of advertisements sent since initialization.

Registartion lifetime: the agent can specify the maximum lifetime in seconds a node can request during registration.

R: shows whether the registration with this agent is required even when using a colocated COA at the MN.

B: It is set when the agent is currently too busy to accept registrations.

H: If the agent offers services as Home Agent.

F: If the agent offers services as the Foreign Agent.

M: used to specify Minimal Encapsulation.

G: used to specify Generic Routing Encapsulation.

r: is set to 0 and must be ignored.

T: indicates reverse tunneling.

The following fields contain the COAs advertised.

Remote host & mobile host communication:Now let us assume that the MN has moved out from its Home Network.The communication process in this situation can be categorised in three phases:


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Agent Discovery:

• The first phase in mobile communication, agent discovery, consists of two subphases.

o(i) A mobile host must discover (learn the address of)a home agent before it leaves its home network.

o(ii) A mobile host must also discover a foreign agent after it has moved to a foreign network.

• This discovery consists of learning the care-of address as well as the foreign agent's address.

• The discovery involves two types of messages : advertisement and solicitation.

• Agent Advertisement: For the first method,foreign agents and home agents advertise their presence periodically using agent advertisement messages.These advertisement messages can be seen as a beacon broadcast into the subnet.For these advertisements Internet Control Message Protocol(ICMP) messages are used with some mobility extensions.


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• Agent Solicitation: If no agent advertisements are present or the inter-arrival time is too high,and a MN has not received a COA by other means,the mobile node must send agent solicitations.These solicitations are based on RFC 1256 for router solicitations.Care must be taken to ensure that these solicitation messages do not flood the network.Typically,a MN can send out three solicitations, one per second,as soon as it enters a new network.If a node does not receive an answer to its solicitations it must decrease the rate of solicitations exponentially to avoid flooding the network until it reaches a maximum interval between solicitations(typically one minute).

• This phase of Agent Discovery can be well understood through animations of Registration in demo section.

Registration: • The second phase in mobile communication is registration.After a mobile node has moved to a foreign network and discovered the foreign agent,it must register.

• There are four aspects of registration :

o (1)The mobile node must register itself with the foreign agent.o (2)The mobile node must register itself with its home agent. This is done normally by the COA providing entity (foreign agent/DHCP server) on behalf of the mobile node.o (3)This registration between MN and HA is for a particular lifetime. Therefore mobile node must renew registration if it has expired.o (4)The mobile node must cancel its registration (deregistration) when it returns home.


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Registration: Timimg Diagram


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ROUTING AND TUNNELING:The home agent, after a successful registration, will begin to attract datagrams destined for the mobile node and tunnel each one to the mobile node at its case-of address. The tunneling can be done by one of several encapsulation algorithms. Encapsulation is a very general technique used for many different reasons, including multicast, multiprotocol operations, authentication, privacy, defeating traffic analysis, and generalpolicy routing.

ENCAPSULATION:Encapsulation is the mechanism of taking a packet consisting of packet header and data putting it into the data part of a new packet.The reverse operation,taking a packet out of data part of another packet,is called decapsulation.


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1 • 1.IP-in-IP encapsulation: In the case of mobile IP, the values of the fields in the new header are selected naturally, with the care-of address used as the destination IP address in the tunnel header. The encapsulating IP header indicates the presence of the encapsulated IP datagram by using the value 4 in the outer protocol field. The inner header is not modified except to decrement the TTL by 1.


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1• IP-in-IP encapsulation:Description

Ver:The version of IP is 4.

Internet Header Length(IHL): denotes the length of the outer header in 32 bit words.

DS(TOS): is just copied from the inner header.

length: covers the complete encapsulated packet.

TTL: Time to live must be high enough so that the packet can reach the tunnel end point.

IP-in-IP: is the type of the protocol used in the IP payload.

IP checksum is calculated as usual.

IP address of HA is the tunnel entry as source address.

Care-of-address of COA is the tunnel exit point as destination address(the COA).


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1• 2.Minimal encapsulation: Redundant fields of IP-in-IP Encapsulation are removed here.

• Minimal encapsulation: Description

• Redundant fields of IP-in-IP Encapsulation are removed here.

•The inner header is different for minimal encapsulation.The type of the following protocol and the address of the MN are needed.If the S bit is set,the original sender address of the CN is included as omitting the source is quite often not an option.No field for fragmentation offset is left in the inner header and minimal encapsulation does not work with already fragmented packets.


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1• 3.GRE Routing encapsulation:


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1• GRE Routing encapsulation: Description

• Generic Routing encapsulation(GRE) allows the encapsulation of packets of one protocol suite into the payload portion of a packet of another protocol suite.

• The packet of one protocol suite with the original packet header and data is taken and a new GRE header is prepended. Together this forms the new data part of the new packet.Finally, the header of the second protocol suite is put in front.

• GRE Header starts with several flags indicating if certain fields are present or not.A minimal GRE Header uses only 4 bytes.

• C: Checksum Field contains a valid IP checksum of the GRE header and the payload.

• R: The R bit indicates if the offset and routing fields are present and contain valid information.

• offset: The offset represents the offset in bytes for the first source routing entry.

• The routing field,if present, has a variable length and contains fields for source routing.If the C bit is set, the offset field is also present, and the offset field is valid only if R is set respectively.

• key: This field is used for authentication. If this field is present,the K bit is set.


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•S: The sequence number bit S indicates if the sequence number field is present, if the s bit is set, strict source routing is used. Sequence number may be used by a decapsulator to restore packet order.

• The recursion control (rec.) is an important field that additionally distinguishes GRE from IP-in-IP and minimal encapsulation. This field represents a counter that shows the number of allowed recursive encapsulations. The default value of this field should be 0,thus allowing only one level encapsulation.

• The reserved fields contains 0 for the GRE version and must be ignored on reception.

•The version field contains 0 for the GRE version.

• The following 2 byte protocol field represents the protocol of the packet following the GRE header.

• The standard header of the original packet follows with the source address of the correspondent node and the destination address of mobile node.


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Mobile IP Operation:

• First, CN wants to send message to the MN. It sends IP packets destined for the MN's home address.These packets will be forwarded to the home network (1 and 2) by normal routing. After that, the HA makes a tunnel (encapsulates the original packets inside a new IP packet), and forwards the packets (3) to the COA (The source IP address is the HA address, and the destination IP address is the COA). After taking off the outer header, the FA forwards the packets directly to the MN by link layer address if it is the FCOA (4). However, if it is the CCOA, the HA forwards the packets directly to the MN where the packets are deencapsulated. Finally, the MN sends the packets back to the CN as usual (5, 6, and 7).


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Optimization: • With the basic Mobile IP protocol all packets to the MN have to go through the HA. This can cause unnecessary overheads for the network between CN and HA, but also between HA and FA(or COA), depending on the current location of the MN.if the Firewall is setup, a firewall does not allow an outgoing packet whose source address is different from its network addresses. This inefficient behavior of a non-optimized mobile IP is called triangular routing. The triangle is made of the three segments, CN to HA, HA to COA/MN, and MN back to CN.

• Triangular Routing Problem can be seen in the Demo section

• One way to optimize the route is to inform the CN of the current location of the MN. The CN can learn the location by caching it in a binding cache which is a part of the local routing table for the CN. Binding cache solution can be seen in demo section.

• Now, consider the situation when the MN changes its FN.


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1 DHCP( Dynamic Host Configuration Protocol )

• The Dynamic Host Configuration Protocol (DHCP) is a network protocol that is used to configure devices which are connected to a network (known as hosts) so that they can communicate on an IP network. It involves clients and a server operating in a client-server model.

• The DHCP server maintains a database of available IP addresses and configuration information. When the server receives a request from a client, the DHCP server determines the network to which the DHCP client is connected, and then allocates an IP address or prefix that is appropriate for the client, and sends configuration information appropriate for that client. DHCP servers typically grant IP addresses to clients only for a limited interval.

• It enables a server to automatically assign an IP address to a computer from a defined range of numbers (i.e., a scope) configured for a given network. DHCP assigns an IP address when a system is started, for example:

o 1. A user turns on a computer with a DHCP client.

o 2. The client computer sends a broadcast request (called a DISCOVER or DHCPDISCOVER), looking for a DHCP server to answer.

o 3. The router directs the DISCOVER packet to the correct DHCP server.

o 4. The server receives the DISCOVER packet. Based on availability and usage policies set on the server, the server determines an appropriate address (if any) to give to the client. The server then temporarily reserves that address for the client and sends back to the client an OFFER (or DHCPOFFER) packet, with that address information. The server also configures the client's DNS servers, WINS servers, NTP servers, and sometimes other services as well.

o 5. The client sends a REQUEST (or DHCPREQUEST) packet, letting the server know that it intends to use the address.

o 6. The server sends an ACK (or DHCPACK) packet, confirming that the client has a been given a lease on the address for a server-specified period of time.


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Master Layout

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• Give START and RESET buttons• Give a text area to display the status of the simulation• For Mobile Host Communication refer slides 34 – 42 • For Agent Discovery and Registration refer slides 43 – 62 • For IP Packet delivery refer slides 63 – 72 • For Optimization: Triangular Routing refer slides 73 – 83 • For Optimization: Binding Cache refer slides 84 – 102 • For Optimization: MN moves – FN to FN refer slides 103 – 142• For Complete process refer slides 143 – 228 • Initially show the statement “ please select the method from the given box above” in the explanation area. Once method is selected, go to the respective slides and show the animation accordingly

Fig. A

Simulation Area

0Control Area

Select the methods Mobile Host Communication Agent Discovery and Registration IP Packet delivery Optimization: Triangular Routing Optimization: Binding Cache Optimization: MN moves – FN to FN Complete process

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Mobile Host Communication

Instruction for the animator Text to be displayed in the working area (DT)

• When Mobile Host Communication is selected, display the figures as shown above

• The buttons shown in the figure are to be displayed• After START is pressed, disable the button • The text in DT and the legend should be displayed• Text given in next slide should be shown in READ ME

• Data Packet• Press START button to see the animation• Press READ ME button to know about

animation

START READ ME

IP packet delivery (When MN is in HN)

Text to be displayed in READ ME:

Consider that a CN wants to send an IP packet to the MN. CN doesn't know anything about the MN's current location and sends the packet with the MN's IP address as the destination address and its own address as the source address.The packet is routed to the router responsible for the home network of MN. The HA will intercept the packet and direct it towards the MN.

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Instruction for the animator Text to be displayed in the working area (DT)• Show the images and text as given in the

above figure• Update the status according to the action

being done• The movement of the red box should be

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Agent Discovery and Registration


• When Agent Discovery and Registration is selected, display the figures as shown above


• Press START button to see the

animation• Press READ ME button to know

about animation

START READ ME

Data Packet

Request Packet

Reply Packet

Advertisement Packet


Registration

MN discovers that it has moved from one Network to another by using one of the two methods:

1.Agent Advertisement :Foreign Agents and Home Agents advertise their presence periodically by broadcasting into the subnet.This is one way for the MN to discover its location.

2.Agent Solicitation :If no agent advertisements are present or the inter-arrival time is too high,and MN has not received a COA by other means,the MN must send agent solicitations.

The main purpose of registration is to inform the HA of the current location for correct forwarding of packets.Registration can be done in 2 ways:

1.If COA is at FA,MN sends its registration request containing the COA to FA which is forwarding the request to the HA.The HA now sets up a mobility binding containing the mobile node's home IP address and the current COA.Additionally,the mobility binding contains the lifetime of the registration, which is negotiated during the registration process.Registration expires automatically after the lifetime and is deleted.

2.If the COA is co-located,registration is simpler.The MN may send the request directly to the HA and vice versa. UDP packets are used for registration requests and reply.

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IP Packet Delivery


• When IP packet delivery is selected, display the figures as shown above• The buttons shown in the figure are to be displayed• After START is pressed, disable the button • The text in DT and the legend should be displayed• Text given in next slide should be shown in READ ME

• Press START button to see the animation• Press READ ME button to know about

animation

START READ ME

IP packet delivery (When MN from HN to FN)

Data Packet

Encapsulated Packet


Consider that a CN wants to send an IP packet to the MN. CN doesn't know anything about the MN's current location and sends the packet with the MN's IP address as the destination address and its own address as the source address.The packet is routed to the router responsible for the home network of MN. The HA will intercept the packet and knowing that MN is currently not in its home network, it will now encapsulate and tunnel the packet to the COA. A new header is put in front of the old IP header showing COA as the destination and HA as the source address. The FA decapsulates the packet i.e. removes the additional header and forwards the original packet with CN as the source and MN as the destination to MN.

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IP Packet Delivery




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IP Packet Delivery




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IP Packet Delivery




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Optimization: Triangular Routing


• When Optimization: Triangular Routing is selected, display the figures as shown above


• Press START button to see the animation• Press READ ME button to know about

animation

START READ ME

Triangular Routing Problem

Data Packet

Encapsulated Packet


Triangular Routing

The inefficient behavior of a non-optimized mobile IP is called triangular routing.

Assume a CN which is in the same network as MN, wants to communicate with MN.

It first sends the data packet to HA of MN, which further encapsulates and tunnels it to MN/COA.

The triangle is made of three segments, CN to HA, HA to COA/MN, and MN back to CN.

With the basic mobile IP protocol all packets to the MN have to go through the HA.

This can cause unnecessary overheads for the network between CN and HA, but also between HA and COA, depending on the current location of the MN.

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Optimization: Binding Cache


• When Optimization: Binding Cache is selected, display the figures as shown above• The buttons shown in the figure are to be displayed• After START is pressed, disable the button • The text in DT and the legend should be displayed• Text given in next slide should be shown in READ ME



about animation

START READ ME

Solution to Triangular Routing – Binding Cache

Data Packet

Binding Request PacketAcknowledgement PacketBinding Update Packet


Binding Cache

One way to optimize the route is to inform the CN of the current location of MN. The CN can learn the location by caching it in a binding cache, which is a part of the local routing table for the CN.

The appropriate entity to inform the CN of the location is the HA.

The optimized mobile IP protocol needs four additional messages.

1. Binding Request : Any node that wants to know the current location of an MN can send a binding request to the HA. If the HA is allowed to reveal the location it sends back a binding update.

2. Binding Update : This message sent by the HA to CN reveals the current location of MN. The message contains the fixed IP address of the MN and the COA. The binding update can request an acknowledgement.

3. Binding Acknowledgement : If requested, a node returns this acknowledgement after receiving a binding update message.

4. Binding Warning : If a node decapsulates a packet for MN, but it is not the current FA for this MN, this node sends a binding warning. The warning contains MN's home address and a target node address, i.e, the address of the node that has tried to send the packet to this MN. The recipient of the warning then knows that the target node could benefit from obtaining a fresh binding for the MN.

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Optimization: MN moves - FN to FN


• When Optimization: MN moves – FN to FN is selected, display the figures as shown above




about animation

START READ ME

MN moves to new FN

Data Packet

Binding Request Packet

Acknowledgement PacketWarning Packet


Binding Update Packet


MN moves to a new FN

The MN might change its location and register with a new foreign agent, FAnew. This registration is also forwarded to the HA to update its location database. Furthermore, FAnew informs FAold about the new registration of MN. MN's registration message contains the address of FAold for this purpose. Passing this information is achieved via an update message, which is acknowledged by FAold.

In this case, CN does not know anything about the new location, so it tunnels its packets for MN to the old FA, FAold. This FAold now notices packets with destination MN, but also knows that it is not the current FA of MN. FAold forwards these packets to the new COA of MN which is FAnew. Also FAold sends a binding warning message to CN informing it about its stale binding cache.

CN then requests a binding update. The HA sends an update to inform the CN about the new location, which is acknowledged. Now CN can send its packets directly to FAnew, which again avoids triangular routing.

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• When Complete process is selected, display the figures as shown above• The buttons shown in the figure are to be displayed• After START is pressed, disable the button • The text in DT and the legend should be displayed• Text given in next slide should be shown in READ ME



about animation

START READ ME

Data Packet

Request Packet

Acknowledgement PacketWarning Packet


Binding Update Packet

Reply Packet

Encapsulated Packet


Initially MN is in its home network. CN routes the data packet to HA, which routes it to MN. Now MN moves to a foreign network.

The registration process begins. FA sends advertisements to MN. MN accepts a packet and gets connected to the FA. MN sends a registration request packet to HA. HA tunnels the reply packet to the FA which then routes the reply to MN. Thus the process of registration terminates.

Now when CN wants to communicate with MN, it as usual routes the packet to HA. HA then encapsulates the packet and routes it to MN. Lets assume that a node CN1 in the same network as MN, wants to communicate with MN. It routes the packet to the HA which then encapsulates the packet and routes it to MN.

Thus we have crossed FA twice and followed a round about way when both CN1 and MN could communicate via FA in the same network. This is the triangular routing problem. The solution to this problem is, CN1 asks the HA for the current location of MN (binding request packet), HA gives the current location of MN (binding update packet), CN1 sends an acknowledge packet to HA. Now CN knows the current location of the MN and so it sends a data packet to MN via FA without crossing it twice.

Let us now assume that MN moves to a new foreign network. The new foreign network starts sending advertisement packets and then the process of registration is completed in the same way. MN updates its HA and old FA. Now if CN wants to communicate with MN, it routes a packet to the old FA as its not aware of the mobile node's change of network. The old FA routes the packet to the new FA, which in turn routes it to MN. Now the old FA sends a warning to CN to convey to it that it's got the wrong address for MN.

On receiving this warning CN now sends a binding update request to HA. HA gives the current location of the MN and so CN can now communicate with MN via the new FA.

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Introduction

Credits

229

Definitions Test your understanding (questionnaire) Lets Sum up (summary) Want to know more…

(Further Reading)

Try it yourself

Interactivity:

Analogy

Slide 1

Slide 3

Slide 230-234

Slide 235

Electrical Engineering

There is no interactivity in this LO

Questionnaire1

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1. What are the three segments the Triangular Routing is made of?

Answers: a) CN to HA, HA to FA and FA to MN b) CN to MN, CN to FA and MN to HAc) CN to HA, HA to MN and MN back to CN

d) CN to FA, FA to MN and MN back to CN

Questionnaire2. What is the purpose of registration when the mobile node is

away from home?

Answers: a) Inform its current location to HA

b) Inform its current location to FA

c) Inform its current location to CN

d) None of the above

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Questionnaire3. Which packet does the old FA sends to CN to convey to it that it's got the wrong address for MN (when MN is in new foreign network)?

Answers: a) Bonding updateb) Warningc) Replyd) Binding Request

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Questionnaire4. Which of the following is/are TRUE?

I. Triangular problem solution- optimizing the route by informing CN, the current location of MN

II. FA is the appropriate entity to inform CN about the location of MN

III. Any node that wants to know the current location of an MN can send a binding request to the HA

Answers: a) I only b) I, II and IIIc) II only d) I and III

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Questionnaire5. If CN knows the location of MN, how will it send the data packet ?

Answers: a) via HAb) via FAc) directly to MN

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Links for further readingReference websites:http://www.classle.net/content-page/mobile-ip

www.cs.jhu.edu/~cs647/class-papers/Routing/mobile_ip.pdf

http://en.wikipedia.org/wiki/Dynamic_Host_Configuration_Protocol http://kb.iu.edu/data/adov.html www.cse.wustl.edu/~jain/cse574-06/ftp/mobile_ip.pdf

Books:

Documents

Mobile Internet Protocol