Transcript Internet - Faruk Hadziomerovic

Internet: network nodes
Host: any computer executing protocol
Hub: repeats signal heard one each port to all ports.
Bridge: understands physical layer addresses, MAC addresses, and learns where
each device is located. It listens to all traffic on LAN. If it finds that packet should
go to another segment it forwards the frame to it. It is store-and-forward device.
Switch: same as bridge however much faster. It redirects a frame only after reading
destination address on a ongoing basis.
Router: Internetwork layer device. It reads entire packet, based on destination
address finds the best route for the packet and sends it.
Faruk Hadziomerovic: Internet notes
Internet: network of networks
star
star
hub
bridge
hub
token
ring
switch
bridge
bridge
Ethernet
router
Faruk Hadziomerovic: Internet notes
Ethernet
Internet protocol stack vs. OSI model (Fig. 1.2)
Application Layer
Presentation Layer
Process Layer
E-mail, FTP, HTTP
Session Layer
Transport Layer
Host-to-host Layer
Network Layer
Internet Layer
Data Link Layer
MAC* Layer
Physical Layer
Physical Layer
TCP, UDP
IP, ARP
Ethernet, Token ring (ATM, Frame Relay**)
Manchester
* Medium Access Control. MAC and Physical layers are called Network Interface Layer.
** not exactly MAC, however, layer above physical
Faruk Hadziomerovic: Internet notes
Two networks connected with a router (Fig. 1.3)
Token ring host
Ethernet host
FTP protocol
FTP
client
FTP
server
TCP protocol
TCP
TCP
router
IP
Ethernet
driver
IP protocol
Ethernet
protocol
IP protocol
IP
Ethernet
driver
Token ring
driver
Ethernet
protocol
IP
Token ring
driver
Ethernet
Token ring
Faruk Hadziomerovic: Internet notes
Internet protocol suite
Process Layer
Port Numbers
T
e
l
n
e
t
23
F
T
P
H
T
T
P
D
N
S
B
O
O
T
P
20/21
80
53
67/68
Host to Host
Layer
IGRP
Internet Layer
88
ARP
0806
Network
Interface
Layer
D
H
C
P
T
F
T
P
69
TCP
UDP
6
17
ICMP
01
IP
0800
S
N
M
P
151/162 520
OSPF
89
RARP
0806
Ethernet, Token Ring, FDDI, SLIP, PPP, etc.
Faruk Hadziomerovic: Internet notes
R
I
P
Protocol
Codes
Internet protocols
TELNET - remote terminal connection service. Allows user terminal to mimic the terminal
at the remote side.
FTP - File Transfer Protocol (put/get file to/from remote machine).
HTTP - Hypertext Transport Protocol.
DNS - Domain Name Server On-line distributed database for translating IP machine names
into IP addresses.
BOOTP - Bootstrap Protocol defines each device autoconfiguration on the server (improvement
to the RARP).
DHCP - Dynamic Host Configuration Protocol (improvement to BOOTP) allows network
administrator to configure workstation by providing dynamic address assignment.
TFTP - Trivial File Transfer Protocol (same as FTP with minimal capability).
SNMP - Simple Network Monitoring Protocol used to monitor IP gateways and networks they
are attached to.
RIP - Routing Information Protocol used to exchange the routing information among small
set of computers (every 30 sec hosts exchange information).
TCP - reliable Transmission Control Protocol (connection oriented).
UDP - unreliable Universal Transport Protocol (connectionless).
IGRP - Interior Gateway Routing Protocol (proprietary routing protocol developed by Cisco).
ICMP - Internet Control Message Protocol part of IP that handles error and control messages.
OSPF - Open Shortest Path First routing protocol.
ARP - Address Resolution Protocol used to dynamically bind IP addresses to physical addresses.
RARP - Reverse ARP used by newly installed machine to find its IP address.
IP - Internet Protocol.
Faruk Hadziomerovic: Internet notes
Encapsulation (Fig. 1.7)
UDP
8 bytes
Ethernet
IP header
14 bytes
20 to 60 bytes
TCP
20 or 24
Application
variable
Application
variable
ICMP
6 + bytes
Faruk Hadziomerovic: Internet notes
CRC
4 bytes
Demultiplexing (Fig. 1.8)
application
application
application
TCP
IGMP
application
UDP
ICMP
IP
ARP
RARP
Ethernet
driver
incoming frame
Faruk Hadziomerovic: Internet notes
Sample (book) network
Solaris 2.2
SunOS 4.1.1
solaris
aix
.1.92
gateway Cisco
router
gemini
.1.32
.1.11
.1.4
Ethernet
.1.183
netb
Telebit
NetBlazer
All IP addresses belong to class B network ID 140.252.xxx.xxx
modem
SLIP (dialup)
BSD/386 1.0
slip
.13.65
BSD/386 1.0
.13.66
modem
SunOS 4.1.3 .1.29
bsdi
sun
.13.35
.13.33
Ethernet
Faruk Hadziomerovic: Internet notes
SVR4
svr4
.13.34
Link Layer (Fig. 2.1)
SLIP (Serial Line IP)
c0
db
ESC
c0
db
dc
db dd
c0
Point-to-point (PPP) protocol
Flag
7E
1
addr
FF
1
Contr
03
1
protocol
2
data
up to 1500
0021
IP datagram
C021
Link control data
8021
network control data
Faruk Hadziomerovic: Internet notes
CRC
2
Flag
7E
1
Ethernet Header
Destin. Addr.
ff
ff
ff
ff
ff
ff
00
00
5e
00
00 00
00
00
c0
a0
Unicast
a0
51
24
c0
a0
08
51
24
00
c0
93
21
51
24
08
00
IP
88
a7
Unicast
Vendor addr
component
06
ARP
Unicast
Multicast
01 00
c0
Unicast
Broadcast
01 00
Type
Source Addr.
Vendor ser.
number
Faruk Hadziomerovic: Internet notes
81
4c
SNMP
IP addressing convention
4 bytes (dec): 140.252.1.13 = 01100000.10101010.00000001.00001011
Class A: Large networks (GM, Ford, etc)
0NNNNNNN
LLLLLLLL
LLLLLLLL
LLLLLLLL
0 - unused, 1 .. 126 ; 127 - loop back
N-Network bits
L-Locally administered
126 Class A networks
16,777,214 hosts/network
Class B: medium size (universities, medium business)
10NNNNNN
NNNNNNNN
128 .. 191
0 .. 255
LLLLLLLL
LLLLLLLL
16,384 Class B networks
65,534 hosts/network
(0 not used, all 1’s broadcast)
LLLLLLLL
2,097,152 Class C networks
254 hosts/network
Class C: small networks (small business)
110NNNNN
192 .. 223
NNNNNNNN
0 .. 255
NNNNNNNN
0 .. 255
Class D: broadcasting
1110MMMM
224 .. 239
MMMMMMMM MMMMMMMM MMMMMMMM
0 .. 255
0 .. 255
0 .. 255
Faruk Hadziomerovic: Internet notes
2,097,152 Class C networks
254 hosts/network
IP subnetting with subnet masks
IP address:
191
255
193
44
Subnet mask:
255
255
252
000
Binary addr:
10111111
11111111
11000001
00101100
Binary Mask:
11111111
11111111
11111100
00000000
Address bits:
NNNNNNNN
NNNNNNNN
SSSSSSI I
N - network bits
S - subnet bits
I - Interface bits.
Natural masks:
Class A : 255.0.0.0
B : 255.255.0.0
C : 255.255.255.0
Faruk Hadziomerovic: Internet notes
IIIIIIII
Subnetting example
Are this two hosts in the same subnet?
source: 161.55.121.33
target: 161.55.131.49
mask: 255.255.248.0
248 = 11111000 mask
121 = 01111001 source
subn= 01111
source subnet
248 = 11111000 mask
248 = 10000011 target
subn= 10000
target subnet
Faruk Hadziomerovic: Internet notes