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WNP-MPR-Fundaments 1

Wireless Networks and Protocols

MAP-Tele

Manuel P. Ricardo

Faculdade de Engenharia da Universidade do Porto


Topics Scheduled for Today

Introduction to Wireless Networks and Protocols

Fundamentals of wireless communications

» Transmission

» Wireless data links and medium access control

» Networking

» Mobility concepts and management

» Research issues

Physical

Network

Transport

Data link

Application

Mo

bil

ity

Sec

uri

ty

Qu

ali

ty o

f S

ervi

ce


Wireless Data Link,

Wireless Medium Access Control


How to model an adaptive wireless data link layer?

How to implement duplex communications in a wireless link?

How to enable multiple access?

What is a random access method?

What is an hidden node? What is an exposed node?

Why is collision avoidance important?

How to avoid the hidden node?

How does the CSMA/CA work?

What is the minimum distance between nodes in CSMA/CA?

What are the services possibly provided by RLC?


Radio Link

Radio link affected by propagation environment

Modulation, coding, power

used to overcome avoiding radio adversities

Service offered by the (wireless) Physical layer

» characterized by data rate (bit/s) and bit error ratio

» modern technologies depends on the radio link operation modes

Operation mode

» pair (modulation, code), typically

» High-Speed Downlink Packet Access (HSDPA/UMTS) 12 modes

» IEEE 802.11a 7 modes

Tx Rx

IN

SSNIR


Radio Link Model –

Continuous Time Markov Chain

Radio link modeled as a Markov Chain

Markov chain state

» Operation mode (modulation, code)

» Si

» Characterized by transmit bit rate ri and bit error ratio ei

Markov chain transition rates

» Process moves only to neighbor states

» Estimating the transition rates:

0 1 2 M-1…

l0

m1

l1

m2

l2

m3

lM-2

mM-1

r0 e0 r1 e1 r2 e2 rM-1 eM-1

Adaptive Transmitter

Physical layer

k

mk

lk

kk+1

nk+1n-

k


Frame Error Ratio, pE

Adaptive transmission tends to maintain BER constant

by controlling modulation, coding, tx power, …

Frame Error Ratio

– pe()- bit error ratio of the uncoded system

– Gc() - coding gain

– Lp – packet length in bits

If different codes are used for header and information fields

LBERFER )1(1 --

ep


Information Rate (Goodput)

Mean Information rate -

1

0

M

i

iic rR

number of bits/symbol

Symbol duration

redundant bits introduced by codes

0 1 2 M-1…

l0

m1

l1

m2

l2

m3

lM-2

mM-1

r0 e0 r1 e1 r2 e2 rM-1 eM-1

Adaptive Transmitter

Physical layer


How to transmit signals in both directions simultaneously?


Duplex Transmission

Duplex – transference of data in both directionsUplink and Downlink channels required

Two methods for implementing duplexing

» Frequency-Division Duplexing (FDD)

– wireless link split into frequency bands

– bands assigned to uplink or downlink directions

– peers communicate in both directions using different bands

» Time-Division Duplexing (TDD)

– timeslots assigned to the transmitter of each direction

– peers use the same frequency band but at different times


Duplex Transmission


How to enable one base station to communicate simultaneously

with multiple mobile nodes?


Multi-Access Schemes

Multi-access schemes

» Identify radio resources

» Assign radio resources to users/terminals using some criteria

Types of multi-access schemes

» Frequency-Division Multiple Access (FDMA)

resources divided in portions of spectrum (channels)

» Time-Division Multiple Access (TDMA)

resources divided in time slots

» Code-Division Multiple Access (CDMA)

resources divided in orthogonal codes

» Space-Division Multiple Access (SDMA)

resources divided in areas


FDMA

» Signal space divided along the frequency axis

into non-overlapping channels

» Each user assigned a different frequency channel

» The channels often have guard bands

» Transmission is continuous over time

channel k

channel 2

time

co

de

channel 1


TDMA

» Signal space divided along the time axis

into non-overlapping channels

» Each user assigned a different cyclically-repeating timeslot

» Transmission not continuous for any user

» Major problem

synchronization among the users in the uplink channels

users transmit over channels having different delays

uplink transmitters must synchronize

timeco

de

… …


CDMA

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

Different bitrates to users

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

co

de

channel 1

channel 2

channel k

…


SDMA

SDMA uses direction (angle) to assign channels to users

Implemented using sectorized antenna arrays

» the 360º angular range divided in N sectors

» TDMA or FDMA then required to channelize users

BS

MT-1

MT-2

MT-k


Combined Multi-Access Techniques

Current technologies combinations of multi-access techniques

» GSM: FDMA and then TDMA to assign slots to users

The cell concept combined multi-access technique

» SDMA + FDMA

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

f3f1

f2

f3f1

f2

f3f1

f5

f6f4

f5

f6f4

f8

f9f7

f8

f9f7

f8

f9f7


Wireless Medium Access Control

Medium Access Control (MAC)

assigns radio resources to terminals along the time

3 type of resource allocation methods

» dedicated assignment

resources assigned in a predetermined, fixed, mode (TDMA)

» random access

terminals contend for the medium (channel)

» demand-based

terminals ask for reservations

using dedicated/random access channels


Hidden, Exposed and Capture Nodes

Signal strength decays with the transmitter-receiver distance

Carrier sensing depends on the position of the receiver

MAC protocols using carrier sensing 3 type of problematic nodes

» hidden nodes

– C is hidden to A

» exposed nodes

– C is exposed to B

» capture nodes

– D captures A

A CB

D


Hidden, Exposed and Capture Nodes

Hidden node C is hidden to A» A transmits to B; C cannot hear A

» If C hears the channel it thinks channel is idle; C starts transmitting

» interferes with data reception at B

» In the range of receiver; out of the range of the sender

Exposed node C is exposed to B» 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

Capture D captures A» A and D transmit simultaneously to B; but signal strength from D much higher than

that from A

A CB

D


MAC Protocols - Aloha, S-Aloha, CSMA

Aloha Efficiency of 18 %if station has a packet to transmit

transmits the packet

waits confirmation from receiver (ACK)

if confirmation does not arrive in round trip time, the station

computes random backofftime retransmits packet

Slotted Aloha 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 Aloha, S-Aloha and CSMA


Aloha versus Time Division Multiplexing


CSMA/CD – Not Used in Wireless

CDMA/Collision Detection Efficiency < 80%– station monitors de medium (carrier sense)

medium free transmits the packet

medium busy waits until medium is free transmits packet

if, during a round trip time, detects a collision

station aborts transmission and stresses collision

(no ACK packet)

Problem of CDMA/CD in wireless networks

Collision detection

near-end interference makes simultaneous transmission and reception difficult


How to minimize collision in a wireless shared medium?


CSMA with Collision Avoidance (CSMA/CA)

S2

DIFS

S3

S1DATA

DIFS S2-bo

DIFS S3-bo

S3-bo-e S3-bo-r

DATA

DIFSS3-bo-r

DATA

- Packet arrivalDATA

- Transmission of DATA DIFS - Time interval DIFS S2-bo - Backoff time, station 2

- Elapsed backoff time, station 3S3-bo-e S3-bo-r

- Remaining backoff time, station 3


CSMA with Collision Avoidance (CSMA/CA)

Station with a packet to transmit monitors the channel activity until an idle period equal to a Distributed Inter-Frame Space (DIFS) has been observed

If the medium is sensed busy a random backoff interval is selected. The backoff time counter is decremented as long as the channel is sensed idle, stopped when a transmission is detected on the channel, and reactivated when the channel is sensed idle again for more than a DIFS. The station transmits when the backoff time reaches 0

To avoid channel capture, a station must wait a random backoff time between two consecutive packet transmissions, even if the medium is sensed idle in the DIFS time


CSMA/CA – ACK Required

AP

DIFS

S2

S1

SIFS

DATA

ACK

DIFS S2-Backoff

SIFS

DATA

ACK


- Transmission of DATA DIFS - Time interval DIFS


CSMA/CA – ACK Required

CSMA/CA does not rely on the capability of the stations to detect a collision by hearing their own transmission

A positive acknowledgement is transmitted by the destination station to signal the successful packet transmission

In order to allow an immediate response, the acknowledgement is transmitted following the received packet, after a Short Inter-Frame Space (SIFS)

If the transmitting station does not receive the acknowledge within a specified ACK timeout, or it detects the transmission of a different packet on the channel, it reschedules the packet transmission according to the previous backoff rules.

Efficiency of CSMA/CA depends strongly of the number of competing stations. An efficiency of 60% is commonly found


How to enable hidden terminals to sense the carrier?

Hidden node: C is hidden to A

A CB

D


RTS-CTS Mechanism

AP

DIFS

S2

S1

SIFS

DATARTS

DIFS S2-bo

DATA


- Transmission of DATA DIFS - Time interval DIFS

CTS

SIFS

SIFS

ACK


RTS-CTS Mechanism

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 station. When the receiver gets a RTS from the sender, it polls the sender by sending a 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 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

In optimum conditions the RTS-CTS mechanism may add an efficiency gain of about 15%


Interference Model – Data and Ack considered

ti , ri - coordinates of transmitter, receiver of link i

No RTS+CTS considered

If the effect of ACK is also considered» links i and j may transmit simultaneously if

where,


Interference Model – Protocol Model

If D=0,

simultaneous transmissions allowed

silent links

ii rtjidist -),(

Why?


Guaranteed Access Control

Polling

» AP manages stations access to the medium

» Channel tested first using a control handshake


Wireless Radio Link Control

MAC layer may not always provide acknowledged delivery

e.g., MAC working over dedicated resources (time slot, code)

Radio Link Control (RLC) sub layer is used in some technologies

Example

» 3 virtual links, represented by 3 RLC instances

» RLC uses service provided the MAC sub-layer

» Possible functions of this MAC sub-layer

– unacknowledged transfer

– selection of appropriate transport format

– priority handling between the data flows generated from different RLC instances

– multiplexing of information generated by RLC instances into common MAC frames

– ciphering of data


Possible Services Provided by RLC

Transparent data transfer» no addition of other information

» possible segmentation of the data, forcing transference of short-length packets

Unacknowledged data transfer» frames are not acknowledged by the RLC receiver

» frame sent by the RLC transmitter has a sequence number

» frame arriving with errors at RLC receiver is discarded

» upper layer at the receiver knows which frames were discarded

» 2 delivery modes at RLC receiver – Out-of-sequence: frame is delivered to the upper-layer as soon as it is received by the RLC receiver

– Duplication avoidance and reordering: frames are delivered by the same order they have been sent and with no duplications

Acknowledged data transfer» guarantees error-free and unique delivery

» upper layer receiver will get the frames by the correct order

» Selective Repeat ARQ is often used

» Short frames used, in order to have low FER


Mobile Networking

Fundaments, IPv6, Mobile IPv6


What are the main differences between L2 and L3 networks?

How can a packet switch support mobility?

What is a tunnel? What is a virtual network?

How does IPv6 work?

How does MIPv6 work?

How to optimize an IPv6 route?


Layered Networking


Switching - Circuits, Datagram, Virtual Circuits

1 2 4 5 1 2 4 5 1 2 4 5

pak 1

pac 2

pac 3 pak 1

pac 2

pac 3 pak 1

pac 2

pac 3

pak 1

pac 2

pac 3 pak 1

pac 2

pac 3 pak 1

pac 2

pac 3

data

Circuit switching(e.g. GSM)

Packet switching(e.g. WLAN)

Virtual circuit switching(e.g. PDP Context, UMTS)

circ

uit

es

tab

lish

men

td

ata

tran

sfer

ence

dat

a tr

ansf

eren

ce

circ

uit

es

tab

lish

men

td

ata

tran

sfer

ence


Packet Switching

Technologies: Ethernet, WLAN, 3GPP-LTE, IP

Destination address is used to switch the packet

a

…input links …forwardingtable

b 1

N

…

N

1

bc

a

bb

c

output linksdestinationaddress

outputlink

a 1

b N

…

c 1


Suppose terminal a moves from port 1 to port 3

What needs to be done, so that terminal a can continue receiving packets?

a


b 1

N

…

N

1

bc

a

bb

c


outputlink

a 1

b N

…

c 1


Ethernet Frame

Ethernet

7x 10101010 10101011

Protocolo=IP


Bridge, Switch

Interconnects

» 2 LAN technologies (e.g. Ethernet and WLAN)

» n segments of the same technology

Bridge builds forwarding tables automatically Address learning

» Source Address of received frame is associated to a bridge input port

» station reachable through 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

MAC

LLC

MAC MAC

RELAY

MAC

LLCBRIDGE

1 n

switchAP


Address Learning and Mobility

router

1 81 8

switch switch

STAMAC = A

1 8

destination

addressinterface

A 1

destination

addressinterface

A 1

router

1 81 8

switch switch

STAMAC = A

1 8

destination

addressinterface

A 8

destination

addressinterface

A 8router

1 81 8

switch switch

STAMAC = A

1 8

router

1 81 8

switch switch

STAMAC = A

1 8

destination

addressinterface

A 8

destination

addressinterface

A 8

1 2

3 4


L2 Networking - Single Tree Required

• Ethernet frame

– No hop-count

– Could loop forever

– Same for broadcast packet

• Layer 2 network

– Required to have tree topology

– Single path between

every pair of stations

• Spanning Tree Protocol (STP)

– Running in bridges

– Helps building the spanning tree

– Blocks ports

L2 Networking - Single Tree Required


One bridge/switch simulates multiple LANs / broadcast domains

One LAN may be extended to other bridges

Virtual LANs

S3

S1

S2

va

vc S6

S4

S5

vb

vc

Preamble SFD L/T FCS

7 octets

DA=Brdc SA=S3 PadData

1 6 6 2 46-1500 4 octets

TAG

4

CFITPID VID=vc

16 3 12

PCP

1 bits

t


L3 Networking – Packet Formats

Options (variable) Pad (variable)

Destination Address

Source Address

TTL

IP identification

Protocol IP checksum

Flags Fragment offset

LengthTOSVer. IHL

Data

0 4 8 16 31

IPv4

IPv6Destination Address (4 words)

Source Address (4 words)

Options (variable number)

Payload length Hop limit

Flow labelVer. Traf Class

Data

0 4 8 16 31

Next header

24


L3 Networking – Router

routetable

memory

CPU forwardtable

forwardcache

LineInterface

MAC

memory

forwardcache

LineInterface

MAC

memory

Switch

Third generation

a


b 1

N

…

N

1

bc

a

bb

c


outputlink

a 1

b N

…

c 1


L3 Networking – Multiple Trees

Every router

» finds the shortest path to the other routers and their attached networks

» Calculates its Shortest Path Tree (SPT)

Routing protocol

» Runs in routers

» Helps routers build their SPT

» RIP, OSPF, BGP, OLSR, AODV, RPL

Destination Cost NextHop

A 1 A

C 1 C

D 2 C

E 2 A

F 2 A

G 3 A

B’s routing view

D

G

A

F

E

B

C


.TCP

Point to connection between a client and a server; port-to-port

Reliable, flow control

Congestion control

Sender

Data (SequenceNum)

Acknowledgment +AdvertisedWindow

Receiver


.Multimedia Traffic - Taxonomy

Applications

Elastic

Intolerant

Real time

Tolerant

Nonadaptive Adaptive

Delay adaptiveRate adaptive

(variation of the packet end-to-end delay)

(packet loss)

(application reaction to packet loss)

(type of reaction)


.RTP+RTCP/UDP

Multimedia traffic

Application-Level Framing

Data Packets (RTP)

» sequence number

» timestamp (app defines “tick”)

» transported as UDP packets

Control Packets (RTCP)

» sent periodically

» report loss rate (fraction of packets received since last report)

» report measured jitter


Traditional TCP/IP Communications Stack

T1

IP

TCP

APP

T1 | T2 T2 | T3

IP

T3 | T4

IP

T5

IP

TCP

APP

host bridge router router host

T4 | T5

bridge

MAC addressbased switching

IP addressbased switching

Ethernetdriver

IP

TCP

Application

Ethernetheader

IPheader

TCPheader

applicationdata

Ethernettrailer

Ethernet frame

IPheader

TCPheader

applicationdata

IP packet

TCPheader

applicationdata

TCP segment

applicationdata

data


Tunnel IP-in-IP

T1

IP1

TCP

APP

T1 | T2 T2 | T3

IP1

T3 | T4 T5

IP2

TCP

APP

H1 bridge R1 R2 Server

T4 | T5

bridge

IP2 IP2

IP1

outer IP header inner IP header data

DA= IP address of R2 (IP1)

SA= IP address of H1 (IP1)

TTL

IP identification

IP-in-IP IP checksum

flags fragment offset

lengthTOSver. IHL

DA= IP address of Server (IP2)

SA= IP address of H1 (IP2)

TTL

IP identification

lay. 4 prot. IP checksum

flags fragment offset

lengthTOSver. IHL

TCP/UDP/ ... payload


.Tunnel PPP over IP (E.g PPTP)

» GRE – virtual point-to-point link

– encapsulates a variety of

network layer protocols

– routers at remote points

– over an IP network

» PPP adequate for – Authentication

– Transporting IP packets

T1

IP1

PPP

IP2

T1 | T2 T2 | T3

IP1

T3 | T4 T5

IP2

TCP

APP

H1 bridge R1 R2 Server

T4 | T5

bridge

GRE

IP2

IP1

TCP

APP

GRE

PPP


IPv6


The Need of a New IP

IPv4

» Small addressing space (232 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 is essential for mobile communications

Internet of things


IPv6 – Improvements

» 128 bit addresses (16 octets, 8 shorts ). No classes

» Better QoS support (flow label)

» Native security functions (peer authentication, data encryption)

» Autoconfiguration (Plug-n-play)

» Routing

» Multicast


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 FF01::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 network prefix = 40 bits

Address Representation


.Reserved Addresses

Allocation Prefix Fraction of

(binary) Address Space

----------------------------------- -------- -------------

Unassigned 0000 0000 1/256

Unassigned 0000 0001 1/256

Reserved for NSAP Allocation 0000 001 1/128

Unassigned 0000 01 1/64


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 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


Addresses –

Link-Local, Site-Local, Global Unicast, Anycast

Link-Local» Used for communication between hosts in the same LAN /link

» Address built from network interface MAC address

» Routers do not foward packets having a Link-Local destination address

Global Unicast» Global addresses

» Address: network prefix + computer identifier

» Structured prefixes

» Network aggregation; less entries in the router forwarding tables

Multicast» Group address; packet received by all the members of the group

Anycast» Group address; packet is received by any (only one) member of the group


Address Formats

Global Unicast address (2000::/3)

Link-Local Unicast address (fe80::/10)

Anycast address

Multicast Address Scope – link, site, global(ff::/8)

001 global rout prefix subnet ID interface ID

n bits m bits 128-n-m bits

1111111010 0 interface ID

10 bits 54 bits 64 bits

subnet prefix 00000000000000

n bits 128-n bits

11111111 group ID

8 bits 112 bits

flags

4

scope

4


.Packet Headers - IPv4 and IPv6

Version HLen TOS Length

Ident Flags Offset

TTL Protocol Checksum

SourceAddr

DestinationAddr

Options (variable)Pad

(variable)

0 4 8 16 19 31

Data

Version Traffic

ClassFlow Label

Payload Lengtht Next Header Hop Limit

SourceAddr (4 words)

DestinationAddr (4 words)


0 4 8 16 24 31

Data

IPv4 IPv6


IPv6 Header

Flow label identifies packet flow

» QoS, resource reservation

» Packets receive same service

Payload length

» Header not included

Hop limit = TTL (v4)

Next header

» Identifies next header/extension header

Options included as extension headers

Version Traffic Class Flow Label

Payload Lengtht Next Header Hop Limit

SourceAddr (4 words)

DestinationAddr (4 words)


0 4 8 16 24 31

Data


Extension Headers

IPv6 HeaderNext Header = TCP

TCP header + data

Routing HeaderNext Header = TCP

TCP header + dataIPv6 HeaderNext Header = Routing

IPv6 HeaderNext Header = Routing

Routing HeaderNext Header = Fragment

Fragment HeaderNext Header = TCP

Fragment of

TCP header + data

IPv6 Hop-by-hop TCPDestination Routing Fragment Authenticate. ESP


.Extension Headers

Hop-by-hop

» additional information, inspected by every node traversed by the packet

» other extension headers inspected only at the destination/pre-defined nodes

Destination

» information for the destination node

Routing

» list of nodes to be visited by the packet

Fragmentation

» made by the source, that must also find MPU

Authentication

» signature of packet header

ESP

» data encryption


.Example of Lab Network

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

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::12000:0:0:1::aa 2000:0:0:e::1


.Configuration examples in Linux

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

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


.Identifier IEEE EUI-64

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|

+----------------+----------------+----------------+ 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


Neighbor Discovery (ND) Protocol

IPv6 node uses ND protocol to

» Find other nodes in the same link /LAN

» Find a node MAC address ND substitutes ARP

» Find router(s) in its network

» Mantaining information about neighbour nodes

ND similar to the IPv4 functions

» ARP IPv4

» ICMP Router Discovery

» ICMP Redirect


.ND Messages

» ICMP messages (over IP); using Link Local addresses

» Neighbor Solicitation

Sent by a host to obtain MAC address of a neighbour / to verify its presence

» Neighbor Advertisement: Answer to the request

» Router Advertisement

Information about the network prefix; periodic or under request

Sent by router to IP address Link Local multicast

» Router Solicitation: host solicits from router a Router Advertisment message

» Redirect: Used by a router to inform na host about the best route to a destination


.IPv6 Address Configuration


.Packet Transmission


Mobility Management


What is the functionality associated to Mobility Management?


Handoff

Transference of a call/session to a new cell/service-area

Caused by

» Radio link degradation terminal movement

» Traffic redistribution

T

switch

AP

TAP

1

2

1

2

Terminal

Mobility


Macro-mobility, Micro-mobility

Mobility types» Macro-mobility: between organizations

» Micro-mobility: in the same organization

Handover types» Vertical handover: between different technologies

» Horizontal handover: same technology, same organization

Internet

Home

Organization 1 Organization 2

Corresponding

host

Same route

Mobile

node

Mobile

node

Internet

Home

Organization 1 Organization 2

Corresponding

host

Mobile

node

Mobile

node

Same route

Macro-mobility Micro-mobility


Mobility Management

Mobility management

» Enables network to be aware of the terminal location

» Maintains the route/connection to the terminal when it moves

Mobility management 2 functions– Location management

– Handoff management


Location Management

Location registration/update

» Terminal informs network about its current access point; regularly

» Network updates terminal location

New Call/Session/Data delivery

» When a new Call/Session/Data arrives to terminal’s home network

network requested to find the terminal location,

either by querying location databases or by paging the terminal

location

database


Handoff Management

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


Data Flow Transference –

Models Commonly Used

I)1)

2)

II) 1) 2) 3)


Flow Transference –

Multicast model, not commonly used

1) 3)2)


Handled at multiple layers

» Data Link: 3GPP, IEEE networks

» Network: Mobile IP, HIP

» Transport: Mobile TCP

» Application: SIP

Security and QoS

Affect Mobility Management

– How to avoid new authentication at every new AP?

– How to guarantee that radio resources are available at the new AP?

Mobility Management

Physical

Network

Transport

Data link

Application

Mo

bil

ity

Sec

uri

ty

Mu

ltic

ast

Qu

ali

ty o

f S

ervi

ce


How does Skype manage computer mobility?


Mobile IPv6


Motivation

How to implement mobility at the IP layer?

RH

MN

HA

IPv6

Internet

RF

CN

MN

Home Network Foreign Network

MN - Mobile Node

HA – Home Agent

CN - Correspondent Node

R - Router


Possible Solutions

DHCP plus dynamic DNS

» MN in the foreign network

» Gets new IP address, uses same name

» Current TCP connections will break

» Works with existing Internet

Mobile IPv6

» Mobile Node maintains its original IP address

» Mobile Node gets a second IP address

» Enables TCP session continuity

» Requires mobility aware nodes

» IETF RFC 3755


MN visits a Foreign Network (./..)

RH

MN

HA

IPv6

Internet

RF

CN

CN HA MN RF MN’| | | | |

| | |MN moves | |

| | +---------------------->|

| | | |radv |

| | | +--------->|

| |binding update(CoA) | |

| |<-----------------------------------+

| |binding ack | | |

| +----------------------------------->|

|echo request| | | |

+ -----------====================================>|

| echo reply | | | |

|<-----------=====================================+

| | | | |

Tunnel HA COA

Care-of address COAIP address of HA

TTLIP identification

IP-in-IP IP checksumflags fragment offset

lengthTOSver. IHL

IP address of MNIP address of CN

TTLIP identification

lay. 4 prot. IP checksumflags fragment offset

lengthTOSver. IHL

TCP/UDP/ ... payload

CoA


.MN visits a Foreign Network (../..)

MN acquires a second IP address (CareOfAddress)

» by DHCP or by listening ICMP Router Advertisement message sent by RF

MN informs HA about its new address

» MN sends Binding-Update; HA sends Binding-Acknowledge

» These are IPv6 messages using a new options mobility header

HA

» starts behaving as MN

» receives traffic sent to MN@home

» tunnels this traffic to the CoA of MN

MN sends traffic to HA, using the tunnel


MN optimizes the Route to CN (./..)

RH

MN

HA

IPv6

Internet

RF

CN CN HA MN RF MN’| | | | |


+ -----------====================================>|

|echo reply | | | |

|<-----------|====================================+

| | | | |

|home test init | | |

|<-----------|====================================+

|care of test init | | |

|<------------------------------------------------+

|care of test| | | |

+------------------------------------------------>|

|home test | | | |

+------------|===================================>|

|binding update | | |

|<------------------------------------------------+

|binding ack | | |

+------------------------------------------------>|


+------------------------------------------------>|


|<------------------------------------------------+

| | | | |

MN

RF

MN


.MN Optimizes the Route to CN (../..)

MN detects packet received in tunnel

Optionally, it decides to optimize the route to the CN

MN informs CN about its new address

» MN sends Binding-Update; CN sends Binding-Acknowledge

» These are IPv6 messages using a new options mobility header

Traffic starts to be exchanged directly between MNCN

» MNCN: use of options destination header

» CNMN: use of routing options header


Route Optimization

IPv6 packets in the CN MN direction

» CN

– Before sending a packet to MN, reads its Bindings cache

– Is there is no entry packet sent as usual

– If there is an entry

Sends packet to CareOfAddress (IPv6 destination address = CareOfAddress)

Includes in the packet a RoutingHeader having 2 hops (list of addresses to be visited)

1º hop CareOfAddress; 2º hop MN HomeAddress

» MN

– Receives packet in CareOfAddress

– Forwards packet to itself (MN home address)

IPv6 packets in the MN CN direction– Source address = CareOfAddress

– Inclusion of DestinationHeader with information about HomeAddress

– CN replaces HomeAddress in the packet source address

so that the socket structure may contain the correct information HomeAddress


.Routing Header -

Packet sent from S to D, through I1, I2, I3As 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:



Address[1] = I1

Address[2] = I3

Address[3] = D

As the packet travels from I2 to I3:



Address[1] = I1

Address[2] = I2

Address[3] = D

As the packet travels from I3 to D:


Destination Address = D Segments Left = 0

Address[1] = I1

Address[2] = I2

Address[3] = I3

List of

visited

nodes

WNP-MPR-Fundaments 97CN HA MN RF MN’|echo request| | | |

+------------------------>| | |

|echo reply | | | |

|<------------------------+ | |

| | |MN moves | |

| | +---------------------->|

| | | |radv |

| | | +--------->|

| | binding update | |

| |<-----------------------------------+

| |binding ack | | |

| +----------------------------------->|


+ -----------====================================>|

|echo reply | | | |

|<-----------|====================================+

| | | | |

|home test init | | |

|<-----------|====================================+

|care of test init | | |

|<------------------------------------------------+

|care of test| | | |

+------------------------------------------------>|

|home test | | | |

+------------|===================================>|

|binding update | | |

|<------------------------------------------------+

|binding ack | | |

+------------------------------------------------>|


+------------------------------------------------>|


|<------------------------------------------------+

| | | | |

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