1. MEDIA ACCESS AND INTERNETWORKING BY SUBASHINI.G
UNIT II
MEDIA ACCESS AND INTERNETWORKING BY
SUBASHINI.G

2. MEDIA ACCESS CONTROL Sub layer of datalink layer.
Provides addressing and channel access control mechanism.

3. ETHERNET IEEE 802.3 formed a standard technology called Ethernet.
Uses CSMA/CD technology.
Ethernet standard found in 1972.
802.3 extended for 100 Mbps called fast ethernet.
1000 Mbps- GigaBit Ethernet

4. CSMA/CD TECHNOLOGY Carrier Sense Multiple Access.
Set of nodes send and receive frames.
Nodes can distinguish between an idle and busy link.
Uses packet radio network as a rout protocol.

5. Ethernet transceiver and adpater
Implemented on a coaxial cable of 500 metres.
Host connect to an ethernet.
Transceiver- device attached to the tape.
It receives incoming signal.
It connected to ethernet adapter which is plugged into the host.
transceiver
ethernet
cable
adapter

6. REPEATER Multiple ethernet segment can be joined by repeaters.
Device that follows signals in all outgoing segments.
Signal is propagated in both directions.
Manchester encoding is used here.

7. HUB
Several point to point segments coming out of a multiwave repeater.
HUB
HUB
HOST
ETHERNET HUB

8. MAC MEDIA ACCESS CONTROL
Algorithm that controls access to a shared ethernet link.
Implemented as hardware in the network adapter.

9. ETHERNET FRAME FORMAT 64 48 48 16 46-1500 32
Preamble(64 bits): allows receiver to synchronize the signal.
Host and destination address(48 bits).
Packet type(16 bits):acts as demux key and identify the higher level protocol.
preamble
Dest
add
Src
type
body
CRC

10. ETHERNET ADDRESS
Each host on the ethrnet has a unique ethernet address.
Address belongs to the adapter not the host.
A sequence of six number separated by colon(ie) 6*1/2
Ex 8:0:2b:e4:b1:2
Every adapter has a unique address .

11. COLLISION Unicast – frame is transmitted to the ethernet.
Broadcast - we are going to set all the bits as 1.
Multicast – the first bit set to 1.
Ethernet adapter accepts all frames and accepts.
Frames address to its own address
Frames address to the broadcast address
Frames address to the multicast address if it has been instructed

12. WIRELESS Wireless signal uses electromagnetic signals.
Use of particular frequency allocated by FCC-Federal Communication Commission- USA
Three categories:
Some bands for government use.
Some bands for AM Radio,FM Radio, telivision,satellite communication.
Some bands for individual organization in certain area.

13. WIRELESS TECHNOLOGIES
BLUETOOTH
WI-FI
WI MAX
3G CELLULAR NETWORKS

14. WI-FI WIRELESS FIDILITY IEEE 802.11
Nodes are peers.
Designed for limited geographical area.
Signal propagation through space.
using two technologies
Frequency hopping- MHz(or)GHz
Direct sequence- MHz

15. COLLISION AVOIDANCE
A and c are said to be hiden nodes because they re not aware of collision
C is called exposed node to B B C D A

16. 802.11 DISTRIBUTION SYSTEM 802.11 packet format
control
dest
add1
add2
add3
seq
add4
Pay
load
CRC

17. BLUETOOTH
Used for short range communication inbetween mobile phones, PDA
Going to operate on 2.45 GHz
Distance is 10 meters
Speed is 2.1 Mbps
Based on piconet
We have advanced technology called Zigbee

18. CONNECTING DEVICES HUB - PHYSICAL LAYER REPEATER - PHYSICAL LAYER
SWITCH - DATA LINK LAYER
BRIDGE DATA LINK LAYER
ROUTER - NETWORK LAYER
GATEWAY - TRANSPORT LAYER

19. APPROACHES FOR SWITCHING AND ROUTING
DATAGRAM APPROACH(OR) CONNECTIONLESS
VIRTUAL CIRCUIT(OR) CONNECTION ORIENTED
SOURCE ROUTING

20. DATAGRAM OR CONNECTIONLESS
Host can send packet anywhere at anytime
Does not care the delivery of data
To decide how to forward a packet a routing table is used

21. VIRTUAL CIRCUIT SWITCHING
TWO STAGES Connection setup Data transfer Also called packet switching or virtual circuit Virtual circuit making virtual connection in between sender and receiver

22. BRIDGES
Accept LAN frames in their inputs and forward them to all other outputs A B C
BRIDGE X Y Z

23. SPANNING TREE ALGORITHM
Keeps all the vertices of the original graph but throws some of the edge
Sub graph that covers all the vertices but contains no cycle
No cycle is formed
Minimum cost and covers all the vertices

24. INTER NETWORKING IP PACKET FORMAT VERSION HLEN TOS LENGTH IDENT FLAGS
OFFSET
TTL
PROTOCOL
CHECKSUM
SOURCE ADDRESS
DESTINATION ADDRESS
OPTIONS(VARIABLE)
PAD(VARIABLE)
DATA

25. IP PACKET FORMAT VERSION- 4 HLEN- HEADER LEN-4 BITS
TOS- TYPE OF SERVICE
LENGTH-16 BIT-NO OF BYTES IN THE DATAGRAM
IDENT- 16 BITS USED FOR FRAGMENTATION
FLAGS/OFFESET- THERE ARE 16 BITS USED BY FRAGMENTATION
TTL- NO OF HOPS
PROTOCOL- 8 BITS-DEMUX KEY
CHECKSUM-16 BITS
DESTINAION/SOURCE ADDRESS-32 BITS EACH
OPTIONS& PAD- 16 BITS(VARYING FROM PACKET TO PACKET)

26. IP SERVICE MODEL PACKET DELIVERY MODEL
Each network has some MTU(Maximum Transmission Unit) ex, Ethernet
FDDI- Fibre Distributed Data Interface
GLOBAL ADDRESSING SCHEME
Global unique address
Combination of network and host
IP address

27. SUB NETTING The division of network into smaller network called subnet
IP Address is 32 bit LAN
One portion indicates a networlk ID and other portion indicates host or router
To connect more host we need subnet
Ex:class B 1
NET H

28. STAGES IN SUBNETTING Delivery to the site Delivery to the sub-net
Delivery to the host
MASKING:
It is a process that extracts the address of physical network from an IP address
Masking can be done whether we have subnet or not

29. MASKING MASK WITH SUBNETTING MASK WITHOUT SUBNETTING MASK 255.255.0.0
IP ADDRESS
N/w ADDRESS
MASK WITH SUBNETTING
MASK
MASK

30. CIDR(CLASSLESS INTER DOMAIN ROUTING)
Also called supernetting
Allocate and specify the internet address used in inter domain routing
Consists of two groups
To identify a network/subnetwork
To identify a host

31. ARP(ADDRESS RESOLUTION PROTOCOL)
ARP PACKET FORMAT
HARDWARE TYPE
PROTOCOL TYPE
H LEN
P LEN
OPERATION
SOURCE HARDWARE ADDRS(BYTE 0-3)
SOURCE HARDWARE
ADDRESS (BYTE 4-5)
SOURCE PROTOCOL
ADDRESS(BYTE 0-1)
ADDRESS (BYTE 2-3)
TARGET HARDWARE
ADDRESS (BYTE 0-1)
TARGET HARDWARE ADDRESS(BYTE 2-5)
TARGET PROTOCOL ADDRESS(BYTE 0-3)

32. DHCP(DYNAMIC HOST CONTROL PROTOCOL)
UNICAST TO SERVER
DHCP RELAY
DHCP
SERVER
OTHER
N/W
HOST

33. DHCP
It is responsible for providing configufration information to host
There is atleast one DHCP server for an administrative domain
It maintains a pool of available devices
DHCP relay unicast the message to the DHCP server and waits for response

34. ICMP(INTERNET CONTROL MESSAGE PROTOCOL)
Defines collection of error messages that are send back to the source host whenever the router is unable to crosses an IP datagram
ERRORS:
Destination host unreachable due to link or node failure
Reassembling process failed

35. THANK YOU