03 Distsyst Net

(multicasting)

4

/.

(latency) --

(transfer rate).

. .

/ ( bps).

(bandwidth)

(baseband)

Msg Transmission Time = latency + MsgLength/data transfer rate

latency

latency

5

hosts

(scalability)

(

). 6

,

, .

,

. .

,

buffer,

.

7

firewall ( ,

).

firewall gateway firewall gateway

.

firewall

. 8

:

/

(..

HTTP

web server).

:

.

IP TCP , (.. spam email)

.

:

,

.

9

(VPNs)

VPNs

firewall

IP .

Internet.

10

.

.

11

--

.

, ,

,

,

.

,

,

.

,

.12

IP Multicast

To IP multicast

IP

IP (multicast

group).

class

D IP ( 1110 bits D IP ( 1110 bits

IPv4 ).

H /

. /

sockets

( sockets

).13

Java API multicast datagrams

MulticastSocket :

MulticastSocket() multicast socket

.

MulticastSocket(int port) multicast socket .

MulticastSocket : MulticastSocket :

void joinGroup(InetAddress mcastaddr) .

void leaveGroup(InetAddress mcastaddr) .

void setTimeToLive(int ttl) time-to-live (TTL)

MulticastSocket

( multicast routers).

1 . 14

(Local Area Networks, LANs)

(Personal Area Networks, PANs)

(Metropolitan Area

Networks, MANs)

(Wide Area Networks, WANs)

(Wireless Local Area (Wireless Local Area

Networks, WLANs)

(Wireless

Metropolitan Area Networks, WMANs)

(Wireless Wide Area

Networks, WWANs)

(internetworks)

16

Baseband

bandwidth bandwidth

Broadband

( )

LANs

/ .

LANs

(segments) (switches)

hubs.

LANs, LANs,

,

.

LAN

1970 (Ethernet, ,

), Ethernet de-facto

LANs.

18

LAN

AdapterAdapter

expansion slot (PCI, PC Card, USB)

main board

adapters

Network Interface Cards (NICs) adapters

Network Interface Component

Bus Network

Tree Network

Star Network

Ring Network

Mesh (=) Network

LAN: Ethernet

IEEE 802.3 standard

: 100 Mbps - 1 Gbps

Ethernet: 10 Mbps

Fast Ethernet: 100 Mbps

Gigabit Ethernet: 1 Gbps

10 Gbps, 100 Gbps

Carrier Sense Multiple Access with Collision Detection

(CSMA/CD)

,

. .

,

Bluetooth,

, PDAs, ,

, ,

.26

video,

50 km. 50 km.

(digital subscriber line, DSL)

modems MANs.

27

WANs

. .

(routers),

.

28

LANs

/ Internet.

IEEE 802.11 (WiFi).

29

Ethernet

( )

802.11 (1-2 Mbps)

802.11b (11 Mbps - 4-5 Mbps )

802.11a (54 Mbps - 22-28 Mbps )

802.11g (54 Mbps - 32 Mbps )

802.11n (108 Mbps - 30-47 Mbps )

ethernet

802.11n (108 Mbps - 30-47 Mbps )

Access Point

To IEEE 802.16 (WiMAX)

,

.

31

GSM.

.

3 (3G)

GSM (2G) .

32

;

/

LANs

LAN Internet LAN Internet

LAN (segments)

WLAN LAN

34

internetwork

Hub LAN

Switch .

.

LANs, Ethernet.

Concentrator repeaterConcentrator repeater

Bridge LANs

data link layer ( 2)

Router

LAN WAN network layer( 3)

hub /

LAN

/

Hub ()

/

hub, hub

37

switch

/,

,

switch

Switch ()

switch

(bridges)

38

Ethernet switch:

(buffering)

(collisions)

(collision domain)

Ethernet Hub buffering:

Ethernet Hubs vs. Ethernet Switches

3939

HighSp

eed

Backpla

ne

CSMA/CD

CSMA/CD

CSMA/CD

CSMA/CD

CSMA/CD

CSMA/CD

CSMA/CD

CSMA/CD

OutputBuffers

InputBuffers

CSMA/CD

CSMA/CD

CSMA/CD

CSMA/CD

CSMA/CD

CSMA/CD

CSMA/CD

CSMA/CD

Hub Switch

routers (Layer 3)

IP

IP

Router ()

40

(circuit switching)

---

bandwidth

[] latency

(packet switching)

bandwidth

latency

-- (store-and-forward)

(Broadcast)

LAN Ethernet

(Frame relay)

.

(frames)

bits .

bits.

.

43

Parlez-vous franais?

,

:

;

bits ;

checksum; ; ;

format ;

byte ordering;

:

(layers)

Ethernet

Ethernet

TCP/IP Ethernet

OSI

(Open Systems Interconnection)(Open Systems Interconnection)

ISO (International

Organization for Interconnection)

7

OSI : 1

.

.

, , , ,

Physical1

: RS-232,

10BaseT, 802.11, Bluetooth

OSI : 2

.

.

( )

acknowledgements

.

Data Link

.

Physical1

2

: Ethernet MAC,

PPP, SLIP

OSI : 3

.

(

Network

Data Link

).

Physical1

2

3

: IP (IPv4, IPv6),

X.25

Transport

OSI : 4

end-to-end (--) .

.

, 4 Transport

Network

Data Link

,

mailbox.

Physical1

2

3

4

: TCP, UDP

Session

Transport

OSI : 5

.

.

.4

5

Transport

Network

Data Link

.

: .

Physical1

2

3

4

: HTTP 1.1, SSL,

NetBIOS

Presentation

Session

Transport

OSI : 6

data

bits

4

5

6

Transport

Network

Data Link

Physical1

2

3

4

: XDR, ASN.1,

MIME, MIDI

Application

Presentation

Session

Transport

OSI : 7

4

5

6

7

Transport

Network

Data Link

Physical1

2

3

4

:email (SMTP, POP, IMAP)file transfer (FTP)

directory services (LDAP)

Application layer (Clients Servers)

client

server

.

, server

.

(Transport Layer)

(= ).

:

connection-oriented

connectionless

Connection-oriented

1. 2. []3. 4.

Connection-oriented

virtual circuit

1. 2. []3. 4.

[ ]

virtual circuit

circuit-switched

Connectionless

-

- / ( )

-

Connectionless

datagram

- / ( )

-

.

( )

datagram

client

client server

virtual circuit

(Network Layer)

65

Ethernet

1 & 2 OSI

Physical (1)

: 10Base-T, 100Base-T, 1000Base-T, .

Data Link (2)

Ethernet Ethernet

Data frame

Data frame

, connectionless

Ethernet

48-bit ethernet address

-

1518-byte MTU

18-byte header, 1500 bytes data

Gigabit ethernet Gigabit ethernet

9000-byte MTU

dest addr src addr framelength

6 bytes 6 bytes 2

data (payload) CRC

446-1500 bytes

18 bytes + data

(ROUTING)

68

(Router)

Router

(..

Ethernet )

(OSI 3)

/

()

Forwarding Process

1.

2. ,

TTL

4.

Forwarding Process

(Forwarding Table)

3.

-

Routing

:

Hop count (# routers )

routing

( (

,

, ).

.

74

/

;

: .

+ +

(..static routes)

-

-

+

+ -

- CPU, , -

Routing

RIP (Routing Information Protocol) routing tables routers

route

OSPF (Open Shortest Path First) .

.

BGP (Border Gateway Protocol) TCP

distance vector

keep-alive

:

(shortest paths)

A C

B

100

10020

20

80Source

50

30

(source)

A

D E

C80

20

20 1010

10

10

1010

Source 30

20 30

IP

Distance Vector vs. Link State

=

-

;

(Distance Vector)

(Link State)

+

Dijkstra Bellman-Ford

.

:RIP, EIGRP,BGP

:OSPF, IS-IS,IDPR

(Distance Vector) (Link State),

,

RIP routing algorithm

if (Rr.link n )


, routing table , router,

.

, RIP

(link) .

router RIP ,

(router),

( ) ,

. .

n

n, .

RIP router o

.


Tr

router l .

t router

, ,

,

RIP .

t 30 seconds.

router

. n,

Send.

routers

Receive ( +1=)

, ,

.

INTERNET PROTOCOLS

82

IP Internet Protocol

1969 4

(ARPA)

::

.

Internet Protocol

Connectionless

internet

IP

.

IP

IP

32 bit

network layer interface:

IP (.. Ethernet

address)address)

IP

IP

32-bit > 4 . !

routers

:

(.. )

IP : &

icsd.aegean.gr195.251.4.2C3 FB 04 02

math.aegean.gr195.251.13.3C3 FB 0D 03

network # host #

16 bits .

routers

195.251.*.* .

IP : &

IP

network #:

host #: ()

network #

host #

IP

:

(classes)

bits IP

class leading bits bits for net # bits for host #

A 0 7 (128) 24 (16M)

:

high bits host number subnet

A 0 7 (128) 24 (16M)

B 10 14 (16K) 16 (64K)

C 110 21 (2M) 8 (256)

IP

IBM: 9.0.0.0 9.255.255.255

00001001 xxxxxxxx xxxxxxxx xxxxxxxxx

network #8 bits

host #24 bits

00001001 10101010 11 xxxxxx xxxxxxxxx

network #8 bits

host #14 bits

Subnet within IBM (internal routers only)

subnet #10 bits

IP

All bits 0

All host# bits 1

Broadcast Broadcast

All bits 1

Broadcast

Leading bits 1110

Class D network (multicast group)

127.0.0.0:

127.0.0.1 loopback (localhost)

Domain Name Server (DNS)

IP

, .. hra.icsd.aegean.gr

IP

.

Domain Name Server DNS

(IP address)

Classless Inter-Domain Routing (CIDR)

class A, B, C :

# of bits

network number

8 (A), 16 (B), 24 (C)

bitsbits

1000 :

22-bit network number (1024 hosts)

class B address (64K hosts)

Classless Inter-Domain Routing

router # bits network?

CIDR address :

32-bit-address/bits-for-network-prefix

128.6.13.3/16

/27 : [1/8 ] of a class C (32 hosts) /27 : [1/8 ] of a class C (32 hosts)

/24 : class C

/16 : class B

CIDR addresses & prefixes

!

To network #

host # CIDR 192.168.5.130/24.

2 bits host number subnet mask

subnet 64 hosts.

96

IPv6 vs. IPv4

IPv4

4 byte (32 bit) addresses

IPv6:

16-byte (128 bit) addresses 16-byte (128 bit) addresses

3.6 x 1038 possible addresses

7 x 1023 IP / m2 !

8 x 1028 IPv4

8-bit hop limit (Time To Live)

Flow label (20-bits)

Network Address Translation (NAT)

External IP address24.225.217.243

External address Virtual

port

Internal

address

Int

port

24.225.217.243 17 192.168.1.1 3455

24.225.217.243 8 192.168.1.2 11231

InternalIP address

192.168.1.x

24.225.217.243 8 192.168.1.2 11231

24.225.217.243 24 192.168.1.1 12489

24.225.217.243 20 192.168.1.3 21908

.1 .2 .3 .4 .5

Network Address Translation (NAT)

UDP/TCP , router

, source IP address port number

.

router source IP address IP

source port number virtual port number

..

IP port number router

.

virtual port number IP address port

number .

router UDP/TCP

destination port number

. port number

.

Transport-layer protocols IP

IP

Transport layer port Transport layer port

number

TCP Transmission Control Protocol

UDP User Datagram Protocol

TCP Transmission Control Protocol

Virtual circuit service

(connection-oriented)

acknowledgement

Checksum Checksum

UDP User Datagram Protocol

Datagram service (connectionless)

checksum , checksum ,

- (bad

packets)

IP header

deviceheader

payload

IP header IP dataTCP/UDPheader

total lengthsvc type (TOS)vers hlen

options and pad

fragment identification flags fragment offsetTTL protocol header checksum

source IP addressdestination IP address

2

0

b

y

t

e

s

Headers: TCP & UDP

deviceheader IP header IP data

TCP/UDPheader

TCP header UDP headerpayload

src port dest portseq numberack number

hdrlen flags

checksum urgent ptroptions and pad

- window

src port dest portseg length checksum

2

0

b

y

t

e

s

8 bytes

Device header (Ethernet)

deviceheader IP header IP data

TCP/UDPheader

frame

payload

dest addr src addr frametype

6 bytes 6 bytes 2

data CRC

446-1500 bytes

18 bytes + data

IP

IP: IP driver

send datareceive data

IP driver

network driver

send packet

to wirefrom wire

receive packet

receive data

IP driver

device driver

Maximum packet size (MTU)

HW headers

HW header

Send operations

device driver

bad/expired data

Device driver

network interface card

network interface

IP driver

IP driver

hardware

Network device

Network card

destination address

(enveloped) (enveloped)

deviceheader

payload

IP header IP data

Device addressing

IP address ethernet address

Address Resolution Protocol (ARP)

1. ARP cache

2. broadcast 2. broadcast

ethernet address

IP address

3. ( timeout)

Documents

03 Distsyst Net