Wireless Networks and Protocols MAP-Tele Manuel P. Ricardo - - PowerPoint PPT Presentation
WNP-MPR-Fundaments 1 Wireless Networks and Protocols MAP-Tele Manuel P. Ricardo Faculdade de Engenharia da Universidade do Porto WNP-MPR-Fundaments 2 Professors Adriano Moreira (WNP Coordinator) Universidade do Minho Manuel P.
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Faculdade de Engenharia da Universidade do Porto
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♦ Adriano Moreira (WNP Coordinator)
♦ Manuel P. Ricardo (mricardo@fe.up.pt)
♦ Rui L. Aguiar
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» provide competences to understand current wireless networks and their functions » provide competences required to create future wireless networks and their functions
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♦ Introduction to Wireless Networks and Protocols
♦ Fundamentals of wireless communications
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Telecommunications systems
» GSM and GPRS » UMTS » TETRA » Broadcast and satellite: DVB, DMB
♦
IEEE wireless data networks
♦
IEEE wireless data networks
» WLAN: 802.11 » WMAN: 802.16 » WPAN: 802.15
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Convergence and interoperability of wireless systems
» 4G wireless networks » 3GPP and Mobile IPv6 approaches » Integration of ad-hoc networks » Research issues
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♦ Quality of service » Characterization and models » Case studies: 3GPP-QoS, IEEE-QoS, IP-QoS » Research issues
♦ Support for services and applications
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♦
Handouts
♦
Recommended papers
♦
Chapters from multiple books
» Wireless and Mobile Network Architectures, Yi-Bing Lin, Imrich Chlamtac Wiley, 2001 » Wireless IP and Building the Mobile Internet, Sudhir Dixit, Ramjee Prasad, Artech House, 2002. » The 3G IP Multimedia Subsystem, Merging the Internet and the Cellular Worlds, Gonzalo Camarillo and Miguel a. Garcia-Martin,Wiley, Second Edition, 2005 » Ad-hoc Wireless Networks, Architectures and Protocols, C. Silva Murthy, B. Manoj, Prentice Hall, 2004
» Ad-hoc Wireless Networks, Architectures and Protocols, C. Silva Murthy, B. Manoj, Prentice Hall, 2004 » Advanced Wireless Networks - 4G Technologies, S. Glisic, Wiley, 2006. » Mobile Communications, Jochen Schiller, Second Edition, Addison-Wesley, 2003 » Wireless Communications - Principles and Practice, Theodore S. Rappaport, Second Edition, Prentice Hall, 2002 » Mobile IP Technology and Applications, Stefan Raab and Madhavi W. Chandra, Cisco Press, 2005 » GSM cellular radio telephony, Joachim Tisal, John Wiley & Sons, 1997 » Wireless Communications and Networks, William Stallings, Prentice Hall, 2002 » WCDMA for UMTS : radio acess for third generation mobile communications, Harri Holma, John Wiley & Sons, 2000 » UMTS networks : architecture, mobility and services, Heikki Kaaranen, et al, John Wiley & Sons, 2001
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♦ Final Exam
♦ Review of 3 papers
♦ Small project
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♦ Introduction to Wireless Networks and Protocols ♦ Fundamentals of wireless communications
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♦ Mobile communications systems characterised by
T switch
AP
T
AP 1 2 1 2
Terminal Mobility Computer Switch Computer AP Wireless link Wired link
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Transport Application Physical Network Data link Mobility Security Multicast Quality of Service
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♦ Introduction to Wireless Networks and Protocols ♦ Fundamentals of wireless communications (brief overview)
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♦ How to transmit signals in both directions simultaneously? ♦ How to enable multiple users to communicate simultaneously?
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♦ Wireless physical layer
Gross bit rate – R, r (bit/s) Bit error ratio – BER, e
♦ In absence of link adaptation
♦ Using link adaptation techniques
1 2 M-1 … λ0 µ1 λ1 µ2 λ2 µ3 λΜ−2 µΜ−1 r0 e0 r1 e1 r2 e2 rM-1 eM-1 Adaptive Transmitter Physical layer
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♦ Duplex – transference of data in both directions
Uplink and Downlink channels required
♦ Two methods for implementing duplexing ♦ Two methods for implementing duplexing
– wireless link split into frequency bands – bands assigned to uplink or downlink directions – peers communicate in both directions using different bands
– timeslots assigned to the transmitter of each direction – peers use the same frequency band but at different times
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♦ How to place several sender-receiver pairs communicating in the
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♦ Multi-access schemes
♦ Multi-access schemes ♦ Multi-access schemes
resources divided in portions of spectrum (channels)
resources divided in time slots
resources divided in codes
resources divided in areas
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into non-overlapping channels
channel k channel 2 time code channel 1
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into non-overlapping channels
synchronization among the users in the uplink channels users transmit over channels having different delays uplink transmitters must synchronize
time code … …
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♦ Each user assigned a code to spread his information signal
» Multi-user spread spectrum (Direct Sequence, Frequency Hopping) » The resulting spread signal
– occupy the same bandwidth – transmitted at the same time
code
♦ Different bitrates to users
Ł control length of codes
♦ Power control required in uplink
» to compensate near-far effect » If not, interference from close user swamps signal from far user
time channel 1 channel 2 channel k …
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♦ SDMA uses direction (angle) to assign channels to users ♦ Implemented using sectorized antenna arrays
♦ Cellular division of the space
BS
MT-1 MT-2 MT-k
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♦ Current technologies Ł combinations of multi-access techniques
♦ The cell concept Ł combined multi-access technique
♦ Cellular planning ♦ Cellular planning
f1 f3 f3 f2 f2 f1 f3 f1 f3 f3 f2 f2 f1 f3 f1 f3 f3 f2 a) Group of 3 cells f4 f2 f6 f3 f5 f2 f1 f6 f3 f5 f7 f2 f3 f4 f5 f7 f2 f1 b) Group of 7 cells c) Group of 3 cells, each having 3 sectors f2 f3 f1 f2 f3 f1 f2 f3 f1 f5 f6 f4 f5 f6 f4 f8 f9 f7 f8 f9 f7 f8 f9 f7
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♦ Medium Access Control (MAC)
♦ 3 type of resource allocation methods
resources assigned in a predetermined, fixed, mode
terminals contend for the channel
terminals ask for reservations using dedicated/random access channels
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♦ Signal strength decays with the path length ♦ Carrier sensing depends on the position of the receiver ♦ MAC protocols using carrier sensing Ł 3 type of nodes
– C is hidden to A
– C is exposed to B
– D captures A
A C B D
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– A transmits to B; C cannot hear A – If C hears the channel it thinks channel is idle; C starts transmitting Ł interferes with data reception at B – In the range of receiver; out of the range of the sender
– B transmits to A; C hears B; C does not transmit; but C transmission would not interfere with A reception – In the range of the sender; out of the range of the receiver
– receiver can receive from two senders – A and D transmit simultaneously to B; but signal from D much higher than that from A
A C B D
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♦ Alhoa Efficiency of 18 %
if station has a packet to transmit
u transmits the packet u waits confirmation from receiver (ACK) u if confirmation does not arrive in round trip time, the station
computes random backofftime retransmits packet
♦ Slotted Alhoa Efficiency of 37 %
stations transmit just at the beginning of each time slot
♦ Carrier Sense Multiple Access (CSMA) Efficiency of 54 %
– station listens the carrier before it sends the packet – If medium busy station defers its transmission
♦ ACK required for Alhoa, S-Alhoa and CSMA
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♦ CDMA/Collision Detection Efficiency < 80%
– station monitors de medium (carrier sense)
u medium free transmits the packet u medium busy waits until medium is free transmits packet u if, during a round trip time, detects a collision
station aborts transmission and stresses collision station aborts transmission and stresses collision (no ACK packet)
♦ Problems of CDMA/CD in wireless networks
Carrier sensing carrier sensing difficult for hidden terminal Collision detection near-end interference makes simultaneous transmission and reception difficult
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♦ How to minimize collision in a wireless medium?
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S2
DIFS
S1
DATA DIFS S2-bo DATA
S3
DIFS S3-bo S3-bo-e S3-bo-r DIFS S3-bo-r DATA
DATA
DIFS
S2-bo
S3-bo-e S3-bo-r
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♦ Station with a packet to transmit monitors the channel activity
♦ If the medium is sensed busy a random backoff interval is
♦ To avoid channel capture, a station must wait a random backoff
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DIFS
S1
SIFS DATA ACK SIFS ACK
AP S2
ACK DIFS S2-Backoff DATA ACK
DATA
DIFS
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♦ CSMA/CA does not rely on the capability of the stations to detect a collision
♦ A positive acknowledgement is transmitted by the destination station to signal
♦ In order to allow an immediate response, the acknowledgement is transmitted ♦ In order to allow an immediate response, the acknowledgement is transmitted
♦ If the transmitting station does not receive the acknowledge within a specified
♦ Efficiency of CSMA/CA depends strongly of the number of competing
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♦ How to enable hidden terminals to sense the carrier?
Hidden node
A C B D
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DIFS
S1
SIFS DATA RTS SIFS SIFS
AP S2
DIFS S2-bo DATA
DATA
DIFS
CTS ACK
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♦
For some scenarios where long packets are used or the probability of hidden terminals is not irrelevant, the efficiency of CSMA/CA can be further improved with a Request To Send (RTS) - Clear to Send (CTS) mechanism
♦
The basic concept is that a sender station sends a short RTS message to the receiver
short CTS message. The sender then sends its packet to the receiver. After correctly receiving the packet, the receiver sends a positive acknowledgement (ACK) to the receiving the packet, the receiver sends a positive acknowledgement (ACK) to the sender
♦
This mechanism is particularly useful to transmit large packets. The listening of the RTS or the CTS messages enable the stations in range respectively of the sender or receiver that a big packet is about to be transmitted. Usually both the RTS and the CTS contain information about the number of slots required to transmit the 4 packets. Using this information the other stations refrain themselves to transmit packets, thus avoiding collisions and increasing the system efficiency.
♦
SIFS are used before the transmission of CTS, Data, and ACK
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In optimum conditions the RTS-CTS mechanism may add an efficiency gain of about 15%
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♦ Polling
» AP manages stations access to the medium » Channel tested first using a control handshake
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♦ Introduction to Wireless Networks and Protocols ♦ Fundamentals of wireless communications (brief overview)
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♦ What networking concepts shall I have present from previous courses? ♦ What are the differences between L2 and L3 networks? ♦ What is a tunnel? What is a virtual network? Why are they relevant? ♦ What is a tunnel? What is a virtual network? Why are they relevant? ♦ What are the differences between IPv4 and IPv6?
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♦
Technologies: ISDN: Basic Rate Access, E1 Ł time slots for 64 kbit/s channels
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Path defined during call establishment, based on the called number
♦
Switching
» Exchange of time slots » In time and in space » Inputs required to be synchronised
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♦ Technologies: ATM, MPLS ♦ Path
» defined during the virtual circuit establishment » Defined as a set of nodes, ports, labels
♦ Switching
» Cells, packets » Exchange of labels
Tabela de translação de portas / canais virtuais 1 M a t 1 N 2 t Entrada M a b c y z c 1 N 2 2 1 N k h m n n g Saída 1
Porta CV Porta CV
comutação espacial comutação de etiqueta b c c y c z y controlo de comutação g h n k k n m g cabeçalho dados a, b, c, ... indicador de canal virtual
b
a
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♦ Technologies: Ethernet, IP ♦ Path defined by packet destination address
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♦ Suppose terminal a moves from port 2 to port 1
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7x 10101010 10101011 Protocolo=IP
Bit stuffing – 5 1s seguidos Ł Ł Ł Ł emissor introduz 0
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♦ Interconnects
» 2 LAN technologies » 2 segments of the same technology
♦ Bridge builds forwarding tables automatically Ł Address learning
Source Address of received frame is associated to a bridge input port
Ł station reachable trough that port station reachable trough that port
♦ Frame forwarding
» When a frame is received, its Destination Address is analysed
– If address is associated to a port frame forwarded to that port – If not frame transmitted through all the ports but the input port
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♦ One bridge/switch simulates multiple LANs / broadcast domains ♦ One LAN may be extended to other bridges
w x w y VLAN 100 VLAN 200 B1 x z VLAN 100 VLAN 200 B2 [da=broadcast; sa=x; data] [da=broadcast; sa=x; vlanid=100; data] [da=broadcast; sa=x; data]
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Version HLen TOS Length Ident Flags Offset TTL Protocol Checksum SourceAddr 4 8 16 19 31 Version
Traffic Class
Flow Label Payload Lengtht Next Header Hop Limit SourceAddr (4 words) 4 8 16 24 31 SourceAddr DestinationAddr Options (variable) Pad (variable) Data DestinationAddr (4 words) Options (variable number) Data
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3ª generation router
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♦ Every router
♦ Routing protocol
Destination Cost NextHop A 1 A C 1 C D 2 C E 2 A F 2 A G 3 A
D G A F E B C
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♦ Point to connection between a client and a server; port-to-port ♦ Reliable, flow control
Sender Data (SequenceNum) Acknowledgment + AdvertisedWindow Receiver
♦ Congestion control
AdvertisedWindow
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Applications Elastic Real time (variation of the packet end-to-end delay) Intolerant Tolerant Nonadaptive Adaptive Delay adaptive Rate adaptive
(packet loss) (application reaction to packet loss) (type of reaction)
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♦ Multimedia traffic ♦ Application-Level Framing ♦ Data Packets (RTP)
♦ Control Packets (RTCP)
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IETF IP address based switching
T1 IP TCP APP T1 | T2 T2 | T3 IP T3 | T4 IP T5 IP TCP APP
host bridge router router host
T4 | T5
bridge IEEE MAC address based switching
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T1 IP TCP APP T1 | T2 T2 | T3 IP T3 | T4 T5 IP TCP APP
H1 bridge R1 R2 Server
T4 | T5
bridge
IP IP IP
data
DA= 2nd IP address of R2 SA= 2nd IP address of H1 TTL IP identification IP-in-IP IP checksum flags fragment offset length TOS ver. IHL DA= Server SA=H1 TTL IP identification
IP checksum flags fragment offset length TOS ver. IHL TCP/UDP/ ... payload
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T1 IP TCP APP T1 | T2 T2 | T3 IP T3 | T4 T5 IP TCP APP
H1 bridge R1 R2 Server
T4 | T5
bridge
IP IP IP PPP GRE GRE PPP
– virtual point-to-point link – encapsulates a variety of network layer protocols – routers at remote points – over an IP network
– Authentication – Transporting IP packets
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♦ IPv4
– Small addressing space (32 bits) – Non-continuous usage – Some solutions used to overcome these problems private networks (NAT), classless networks (CDIR)
♦ IETF developed new IP version: IPv6
– Same principles of IPv4 – Many improvements – Header re-defined
♦ IPv6 may be relevant for mobile communications
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♦ 8 x 16 bit, hexadecimal. Separated by : 47CD : 1234 : 3200 : 0000 : 0000 : 4325 : B792 : 0428 ♦ Compressed format: FF01:0:0:0:0:0:0:43
♦ Compatibility with IPv4: 0:0:0:0:0:0:13.1.68.3 or ::13.1.68.3 ♦ Loopback address: ::1 ♦ Network prefix described by / , same as IPv4 » FEDC:BA98:7600::/40
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Allocation Prefix Fraction of (binary) Address Space
0000 0000 1/256 Unassigned 0000 0001 1/256 Reserved for NSAP Allocation 0000 001 1/128 Unassigned 0000 01 1/64 Unassigned 0000 1 1/32 Unassigned 0001 1/16 Unassigned 0001 1/16 Global Unicast 001 1/8 Unassigned 010 1/8 Unassigned 011 1/8 Unassigned 100 1/8 Unassigned 101 1/8 Unassigned 110 1/8 Unassigned 1110 1/16 Unassigned 1111 0 1/32 Unassigned 1111 10 1/64 Unassigned 1111 110 1/128 Unassigned 1111 1110 0 1/512 Link-Local Unicast Addresses 1111 1110 10 1/1024 Site-Local Unicast Addresses 1111 1110 11 1/1024 Multicast Addresses 1111 1111 1/256
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– Used for communication between hosts in the same LAN /link – Address built from MAC address – Routers do not foward packets having Link-Local destination addresses
– Not used anymore – Not used anymore
– Global addresses – Address: network prefix + computer identifier – Structured prefixes Network aggregation; less entries in the router forwarding tables
– Group address; packet is received by any (only one) member of the group
– Group address; packet received by all the members of the group
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| n bits | m bits | 128-n-m bits | Global Unicast Address +------------------------+-----------+----------------------------+ (2000::/3) |001 global rout prefix | subnet ID | interface ID | +------------------------+-----------+----------------------------+ | 10 | | bits | 54 bits | 64 bits | Link-Local Unicast address +----------+-------------------------+----------------------------+ (fe80::/10) |1111111010| 0 | interface ID | +----------+-------------------------+----------------------------+ | 10 | | bits | 54 bits | 64 bits | Site-Local Unicast address +----------+-------------------------+----------------------------+ (fec0::/10) |1111111011| subnet ID | interface ID | +----------+-------------------------+----------------------------+ | n bits | 128-n bits | Anycast address +------------------------------------------------+----------------+ | subnet prefix | 00000000000000 | +------------------------------------------------+----------------+ | 8 | 4 | 4 | 112 bits | +------ -+----+----+---------------------------------------------+ |11111111|flgs|scop| group ID | +--------+----+----+---------------------------------------------+
Multicast address Scope – link, site, global, ... (ff::/8)
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Version HLen TOS Length Ident Flags Offset TTL Protocol Checksum SourceAddr 4 8 16 19 31 Version
Traffic Class
Flow Label Payload Lengtht Next Header Hop Limit SourceAddr (4 words) 4 8 16 24 31 SourceAddr DestinationAddr Options (variable) Pad (variable) Data DestinationAddr (4 words) Options (variable number) Data
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♦ Flow label identifies packet flow
♦ Payload length
Version
Traffic Class
Flow Label Payload Lengtht Next Header Hop Limit SourceAddr (4 words) 4 8 16 24 31
♦ Payload length
♦ Hop limit = TTL (v4) ♦ Next header
♦ Options included as extension headers
DestinationAddr (4 words) Options (variable number) Data
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IPv6 Header
Next Header = TCP
TCP header + data Routing Header
Next Header = TCP
TCP header + data IPv6 Header
Next Header = Routing
IPv6 Header
Next Header = Routing
Routing Header
Next Header = Fragment
Fragment Header
Next Header = TCP
Fragment of TCP header + data IPv6 Hop-by-hop TCP Destination Routing Fragment Authenticate. ESP
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additional information, inspected by every node traversed by the packet Other header are inspected only at the destination or at pre-defined nodes
Information for the destination node
Information for the destination node
List of nodes to be visited by the packet
Made by the source; it shall find MPU
Authentication (signature) of packet header
Data encryption
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As the packet travels from S to I1: Source Address = S Hdr Ext Len = 6 Destination Address = I1 Segments Left = 3 Address[1] = I2 Address[2] = I3 Address[3] = D As the packet travels from I1 to I2: Source Address = S Hdr Ext Len = 6 Destination Address = I2 Segments Left = 2 Destination Address = I2 Segments Left = 2 Address[1] = I1 Address[2] = I3 Address[3] = D As the packet travels from I2 to I3: Source Address = S Hdr Ext Len = 6 Destination Address = I3 Segments Left = 1 Address[1] = I1 Address[2] = I2 Address[3] = D As the packet travels from I3 to D: Source Address = S Hdr Ext Len = 6 Destination Address = D Segments Left = 0 Address[1] = I1 Address[2] = I2 Address[3] = I3
List of visited nodes
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quadro porta banc_3 banc_6 pc3---[HUB]---pc2----+ +----pc2---[HUB]---pc3 2000:0:0:3::/64 | | 2000:0:0:6::/64 | | banc_2 | | banc_5 banc_2 | | banc_5 pc3---[HUB]---pc2--[HUB]-+ +-[HUB]--pc2---[HUB]---pc3 2000:0:0:2::/64 | | | | 2000:0:0:5::/64 | | | | banc_1 | | | | banc_4 pc3---[HUB]---pc2----+ | | +----pc2---[HUB]---pc3 2000:0:0:1::/64 | | 2000:0:0:4::/64 | | 2000:0:0:e::/64| |2000:0:0:d::/64 | | [routerv6] 2000:0:0:1::1 2000:0:0:1::aa 2000:0:0:e::1
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tux13:~# /sbin/ifconfig eth0 inet6 add 2000:0:0:1::1/64 tux13:~# ifconfig eth0 eth0 Link encap:Ethernet HWaddr 00:C0:DF:08:D5:99 inet addr:172.16.1.13 Bcast:172.16.1.255 Mask:255.255.255.0 inet6 addr: 2000:0:0:1::1/64 Scope:Global inet6 addr: fe80::2c0:dfff:fe08:d599/10 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:81403 errors:0 dropped:0 overruns:0 frame:0 TX packets:2429 errors:0 dropped:0 overruns:0 carrier:0 TX packets:2429 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:100 RX bytes:4981344 (4.7 MiB) TX bytes:260692 (254.5 KiB) Interrupt:5 tux13:~# /sbin/route -A inet6 add 2000::/3 gw 2000:0:0:1::aa tux13:~# route -A inet6 Kernel IPv6 routing table Destination NextHop Flags Metric Ref Use Iface ::1/128 :: U 0 0 0 lo 2000:0:0:1::1/128 :: U 0 0 0 lo 2000:0:0:1::/64 :: UA 256 0 0 eth0 2000::/3 2000:0:0:1::aa UG 1 0 0 eth0 fe80::2c0:dfff:fe08:d599/128 :: U 0 0 0 lo fe80::/10 :: UA 256 0 0 eth0 ff00::/8 :: UA 256 0 0 eth0 ::/0 :: UDA 256 0 0 eth0
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Method to create a IEEE EUI-64 identifier from an IEEE 48bit MAC identifier. This is to insert two octets, with hexadecimal values of 0xFF and 0xFE, in the middle of the 48 bit MAC (between the company_id and vendor supplied id). For example, the 48 bit IEEE MAC with global scope: |0 1|1 3|3 4| |0 5|6 1|2 7| +----------------+----------------+----------------+ |cccccc0gcccccccc|ccccccccmmmmmmmm|mmmmmmmmmmmmmmmm| |cccccc0gcccccccc|ccccccccmmmmmmmm|mmmmmmmmmmmmmmmm| +----------------+----------------+----------------+ 00:C0:DF:08:D5:99 where "c" are the bits of the assigned company_id, "0" is the value of the universal/local bit to indicate global scope, "g" is individual/group bit, and "m" are the bits of the manufacturer-selected extension identifier. The interface identifier would be of the form: |0 1|1 3|3 4|4 6| |0 5|6 1|2 7|8 3| +----------------+----------------+----------------+----------------+ |cccccc1gcccccccc|cccccccc11111111|11111110mmmmmmmm|mmmmmmmmmmmmmmmm| +----------------+----------------+----------------+----------------+ fe80::2c0:dfff:fe08:d599
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♦ IPv6 node uses ND for
ND substitutes ARP
♦ ND similar to the IPv4 functions
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Sent by a host to obtain MAC address of a neighbour / to verify its presence
Information about the network prefix; periodic or under request Sent by router to IP address Link Local multicast
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♦ Introduction to Wireless Networks and Protocols ♦ Fundamentals of wireless communications (brief overview)
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♦ What are the key management concepts? ♦ What functionality is associated to Mobility Management?
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♦ Transference of a call, or session, to a new cell / service-area ♦ Caused by radio link degradation ( terminal movement)
T switch
AP
T
AP 1 2 1 2
Terminal Mobility
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♦ (Terminal) Mobility types
♦ Handover types ♦ Handover types
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Internet Home Corresponding host Same route Organization 1 Organization 2 Mobile node Mobile node
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Internet Home Corresponding host Same route Organization 1 Organization 2 Mobile node Mobile node
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♦ Mobility management
♦ Mobility management Ł 2 functions
– Location management – Handoff management
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♦ Location registration/update ♦ Location registration/update
♦ New Call/Session/Data delivery
network requested to find the terminal location, by querying location databases (or by paging the terminal)
location database
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♦ Maintains terminal connection/routes when terminal moves ♦ Initiation: need for handoff identified ♦ New connection/route generation
» Resources found for the handoff connection
– In Network-Controlled Handoff (NCHO) the network finds the resources – In Mobile-Controlled Handoff (MCHO) terminal finds resources, network approves
» Routing operations performed
♦ Data-flow control: delivery of data from old to new paths, maintaining QoS
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1.
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Network Transport Application ce
Physical Data link Mobility Security Multicast Quality of Service
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♦ How does Skype manage computer mobility?
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♦ Introduction to Wireless Networks and Protocols ♦ Fundamentals of wireless communications (brief overview)
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Network Applications f Service
Network Wireless Link Mobility Security Multicast Quality of S
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Network Wireless Link Applications Mobility Security Multicast Quality of Service
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Network Wireless Link Applications
ecurity ulticast uality of Service
Wireless Link Mo Sec Mu Qu
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♦ Moving networks ♦ Multi-layer mobility management ♦ Fast authentication techniques ♦ Multilayer security techniques
Network Wireless Link Applications Mobility Security Multicast Quality of Service
♦ Multi-layer multicast management ♦ M N communications, P2P over wireless networks ♦ Mobility and security ♦ Mobility and QoS ♦ Secure multicast ♦ Multicast with QoS
Wireless Link Mo Se M Qu
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♦ Ajay Chandra, V. Gummalla, and John O. Limb, “Wireless
♦ Fotis Foukalas, Vangelis Gazis, and Nancy Alonistioti, “Cross-
♦ Provide a 2-page summary