Why does Mobile IP use two IP addresses: a fived home address and a care of addr

Question

Why does Mobile IP use two IP addresses: a fived home address and a care of address that changes at each new point of What is Mobile IP? Explain the various Components of Mobile IP and support your answer to show steps followed to get connection and from mobile mode (MN)in case of transmission and receiving respectively What are the different Wireless Media Access Control mechanisms? What are the piconet and statement in bluetooth? Distinguish between the role of HLR & VLR. In WLAN, how is the hidden terminal is compensated for in CSMA/CA (first scheme) without using RTS/CTS? What is MAC and what are important parameters for CSMA? What are the reasons behand that a wireless transmitter can not detect collision? Explain when mobile IP is needed Why and where is encapsulation needed for mobile IP? What is meant by Agent Discovery, registration and tunneling in mobile IP? Explain how tunneling works for mobile IP using IP-in-IP. Discuss the advantages and disadvantages of this method. Explain two solution approaches to support fast handoffs. What is the purpose of home-address and care of address per mobile host in mobile IP? What are WEP, WPA and Wardriving? What does WPA stand for? What is the difference between WPA and WPA2? Which of them is the strongest security algorithm? Why? The principal WLAN threats are eavesdropping, altering or inserting messages, and disruption. Explain in details how eavesdropping can be countermeasured. What are Wireless Security threats? What are Wireless Security Techniques

Explanation / Answer

why does mobile ip has two ip addresses: a fixed home address and a care of address that changes at each new point of attachment?
Ans:] Mobile IP enables routing of IP datagrams to mobile nodes.

The fixed home address of a mobile device is the IP address assigned to the device within its home network.

The mobile node's home address always identifies the mobile node, regardless of its current point of attachment to the Internet or an organization's network.

When away from home, a care-of address associates the mobile node with its home address by providing information about the mobile node's current point of attachment to the Internet or an organization's network.

The care-of address of a mobile device is the network-native IP address of the device when operating in a foreign network

Mobile IP uses a registration mechanism to register the care-of address with a home agent. The home agent redirects datagrams from the home network to the care-of address by constructing a new IP header that contains the mobile node's care-of address as the destination IP address.

What is mobile IP? Explain the various components of Mobile IP and support your answer to show steps followed to get connection to and from mobile node(MN) in case of transmission and receiving respectively
Ans:]Mobile IP (or MIP) is an 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 IP is a way of performing three related functions:
Agent Discovery - Mobility agents advertise their availability
on each link for which they provide service.
Registration - When the mobile node is away from home,
it registers its care-of address with its home agent.
Tunneling - In order for datagrams to be delivered to the
mobile node when it is away from home, the home agent has
to tunnel the datagrams to the care-of address.
A Mobile Node (MN) is responsible for discovering whether it is connected to its home network or has moved to a foreign network. HA’s and FA’s broadcast their presence on each network to which they are attached. They are not solely responsible for discovery, they only play a part. When connected to a foreign network, a MN has to determine the foreign agent care-of-address being offered by each foreign agent on the network.

What are different wireless media access control mechanisms?
Ans:] channel coding, bit interleaving, frequency/space diversity, and
equalization
Duplexing, Frame type

What are piconet and scatternet in bluetooth?
Ans:] Piconet is a basic unit of bluetooth networking. Devices function as master and slave in piconet. There are two configurations namely one master and one slave or one master and multiple slaves. Master will determine channel and phase.
Scatternet: The bluetooth network consisting of one or more piconets is known as scatternet. The devices in one piconet type may function as master or slave in another piconet type of the same scatternet. This bluetooth network type allows many devices to share the same network area. This will allow efficient use of the bandwidth.

Distinguish between the role of HLR and VLR?

Ans:] The Home Location Register aka HLR is a mobile operator database that includes details of subscribers such as phone number, billing details, phone status - parameters that are valuable if an SMS didn't get delivered. This data is accessable by all Mobile Switching Centres (MSC) and Visiting Location Registers (VLR).

Visiting Location Register supports roaming functions for users outside the coverage area of their own HLR. It contains mostly the same data from the HLR yet this information is stored temporarily containing mostly duplicated information relevant to the subscriber network location. As a phone numbers may operate outside their home network at some times, the VLR can locate in which network the number is currently roaming.

The VLR database contains information about all the mobile subscribers currently located in an MSC service area.

Thus there is one VLR for each MSC in a network. The VLR temporarily stores subscription information

The HLR is a centralized network database that stores and manages all mobile subscriptions belonging to a specific operator. It acts as a permanent store for a person’s subscription information until that subscription is canceled. The informationstored includes:· Subscriber identity· Subscriber supplementary services· Subscriber location information· Subscriber authentication information

In WLAN, how is the hidden terminal is compensated for CSMA/CA without using RTS/CTS?
Ans:]If a packet is lost because of the hidden terminal , the receiver will not send acknowledge so the sender will send it again.

What is MAC and what are important parameters for CSMA?
Ans:] MAC Means Medium Access Control. The main job of the MAC protocol is to regulate the usage of the medium, and this is done through a channel access mechanism. A channel access mechanism is a way to divide the main resource between nodes, the radio channel, by regulating the use of it. It tells each node when it can transmit and when it is expected to receive data.
CSMA/CA (Carrier Sense Multiple Access/Collision Avoidance) is the channel access mechanism used by most wireless LANs in the ISM bands. A channel access mechanism is the part of the protocol which specifies how the node uses the medium : when to listen, when to transmit...
The basic principles of CSMA/CA are listen before talk and contention. This is an asynchronous message passing mechanism (connectionless), delivering a best effort service, but no bandwidth and latency guarantee (you are still following ?). It's main advantages are that it is suited for network protocols such as TCP/IP, adapts quite well with the variable condition of traffic and is quite robust against interferences.

CSMA/CA is fundamentally different from the channel access mechanism used by cellular phone systems

What are the reason behind that a wireless transmitter can not detect collision?
Ans:] On a wire, the transceiver has the ability to listen while transmitting and so to detect collisions (with a wire all transmissions have approximately the same strength). But, even if a radio node could listen on the channel while transmitting, the strength of its own transmissions would mask all other signals on the air. So, the protocol can't directly detect collisions like with Ethernet and only tries to avoid them.

Explain when mobile IP is needed?
Ans:]In many applications (e.g., VPN, VoIP), sudden changes in network connectivity and IP address can cause problems. Mobile IP was designed to support seamless and continuous Internet connectivity.
Mobile IP is required in wired and wireless environments where users need to carry their mobile devices across multiple LAN subnets. Examples of use are in roaming between overlapping wireless systems, e.g., IP over DVB, WLAN, WiMAX and BWA.
It is often used in 3G systems to allow seamless IP mobility between different packet data serving node (PDSN) domains
Why and where is encapsulation needed for mobile ip
Ans:]Once a mobile node on a foreign network has completed a successful registration with its home agent, the Mobile IP datagram forwarding process described in the general operation topic will be fully “activated”. The home agent will intercept datagrams intended for the mobile node as they are routed to its home network, and forward them to the mobile node. This is done by encapsulating the datagrams and then sending them to the node's care-of address
Encapsulation is required because each datagram we intercept and forward needs to be resent over the network to the device's care-of address. In theory, the designers might conceivably have done this by just having the home agent change the destination address and stick it back out on the network, but there are various complications that make this unwise. It makes more sense to take the entire datagram and wrap it in a new set of headers before retransmitting.

What is meant by Agent Discovery, registration and tunneling in mobile IP?
Ans:] Agent Discovery:

Agent Discovery is the method by which a mobile node determines whether it is currently connected to its home network or to a foreign network, and by which a mobile node can detect when it has moved from one network to another.

When connected to a foreign network, the methods also allow the mobile node to determine the foreign agent care-of address being offered by each foreign agent on that network. Mobile IP extends ICMP Router Discovery as its primary mechanism for Agent Discovery. An Agent Advertisement is formed by including a Mobility Agent Advertisement Extension in an ICMP Router advertisement message
Registration:

Mobile IP registration provides a flexible mechanism for mobile nodes to communicate their current reachability information to their home agent. It is the method by which mobile nodes request forwarding services when visiting a foreign network, inform their home agent of their current care-of address, renew a registration which is due to expire, and/or deregister when they return home.
Tunneling:
Tunneling, also known as "port forwarding," is the transmission of data intended for use only within a private, usually corporate network through a public network in such a way that the routing nodes in the public network are unaware that the transmission is part of a private network. Tunneling is generally done by encapsulating the private network data and protocol information within the public network transmission units so that the private network protocol information appears to the public network as data. Tunneling allows the use of the Internet, which is a public network, to convey data on behalf of a private network.

Explain how tunneling works for mobile IP using IP in IP. Discuss the advantages and disadvantes of this method?
Ans:]Tunnelling simply means that a packet is encapsulated at tunnel entry and decapsulated at tunnel exit. The packet is thus payload of the outer packet inside the tunnel. IP-in-IP encapsulation is the simple case of using IP for encapsulating other IP packets. This is simple because all devices already know how to insert payload into an IP packet. Bandwidth is wasted by transferring the same field several times.
Explain two solution approaches to support fast handoffs?
Ans:] Two basic types of handoff are defined -- viz. hard handoff and soft handoff.

With hard handoff, the link to the prior base station is terminated before or as the user is transferred to the new cell’s base station.
Soft handoff is beneficial because it reduces interference into other cells and improves performance by using macro diversity.

What is the purpose of home-address and care of address per moble host in mobile IP?
Ans:]Home address
The home address of a mobile device is the IP address assigned to the device within its home network.
Care-of address
The care-of address of a mobile device is the network-native IP address of the device when operating in a foreign network.
What are WEP, WPA and Wardriving?
Ans:]WEP:Wireless encryption protocols that are intended to protect the information you send and receive over a wireless network
WPA:Wi-Fi Protected Access (WPA) is a security standard for users of computing devices equipped with wireless internet connections, or Wi-Fi. It improved upon and replaced the original Wi-Fi security standard, Wired Equivalent Privacy (WEP). WPA provides more sophisticated data encryption than WEP, and it also provides user authentication -- WEP's user authentication was considered insufficient.
Wardriving: Wardriving is the act of searching for Wi-Fi wireless networks by a person in a moving vehicle, using a portable computer, smartphone or personal digital assistant (PDA).
What does WPA stand for?
Ans:] Wi-Fi Protected Access (WPA)

What is the difference between WPA and WPA2? Which of them is the strongest security algorithm? Why?
Ans:]Wi-Fi Protected Access was the Wi-Fi Alliance’s direct response and replacement to the increasingly apparent vulnerabilities of the WEP standard. It was formally adopted in 2003, a year before WEP was officially retired. The most common WPA configuration is WPA-PSK (Pre-Shared Key). The keys used by WPA are 256-bit, a significant increase over the 64-bit and 128-bit keys used in the WEP system.
Wi-Fi Protected Access II (WPA2)
WPA has, as of 2006, been officially superseded by WPA2. One of the most significant changes between WPA and WPA2 was the mandatory use of AES algorithms and the introduction of CCMP (Counter Cipher Mode with Block Chaining Message Authentication Code Protocol) as a replacement for TKIP (still preserved in WPA2 as a fallback system and for interoperability with WPA).

Currently, the primary security vulnerability to the actual WPA2 system is an obscure one (and requires the attacker to already have access to the secured Wi-Fi network in order to gain access to certain keys and then perpetuate an attack against other devices on the network). As such, the security implications of the known WPA2 vulnerabilities are limited almost entirely to enterprise level networks and deserve little to no practical consideration in regard to home network security.

Unfortunately, the same vulnerability that is the biggest hole in the WPA armor, the attack vector through the Wi-Fi Protected Setup (WPS), remains in modern WPA2-capable access points. Although breaking into a WPA/WPA2 secured network using this vulnerability requires anywhere from 2-14 hours of sustained effort with a modern computer, it is still a legitimate security concern and WPS should be disabled (and, if possible, the firmware of the access point should be flashed to a distribution that doesn’t even support WPS so the attack vector is entirely removed).

What are wireless security threats?
Ans:]1. Rogue access points
2. Misconfiguration
3. Unmanaged use of wireless outside the enterprise
4. Hackers
What are wireless security techniques?
Ans:]Wireless security is the prevention of unauthorized access or damage to computers using wireless networks. The most common types of wireless security are Wired Equivalent Privacy (WEP) and Wi-Fi Protected Access (WPA). WEP is a notoriously weak security standard.

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