1. Subject Name: Computer Communication Networks Subject Code: 10EC71
Prepared By: Kala H S & Megha Gupta
Department: ECE
Date:
9/18/2018

2. TRANSPORT LAYER: Process to Process Delivery
Unit - 8
TRANSPORT LAYER: Process to Process Delivery
9/18/2018

3. TOPICS TO BE COVERED Process to Process Delivery UDP TCP
Domain Name System
Resolution
9/18/2018

4. PROCESS to PROCESS DELIVERY
Data link layer is responsible for node-to-node delivery of frames between neighboring nodes.
Network layer is responsible for host-to-host delivery of datagrams between two different hosts.
However at any time several processes may be running on source host and destination host. To
complete the communication we need delivery of data from one process running on source host
to another running on destination host. This is called process-to-process delivery and is done by the transport layer.
9/18/2018

5. IANA Ranges
The Internet Assigned Number Authority has divided port numbers into three ranges:
1. Well – known ports: These port numbers range from 0 to 1023 and are assigned and
controlled by IANA.
2. Registered ports: Ranging from 1024 to and are not assigned or controlled by IANA.
They can only be registered with IANA to prevent duplication.
3. Dynamic ports: Ranging from to are neither controlled nor registered by IANA. They can be used by any process and are ephemeral ports.
9/18/2018

6. Socket Address
Process – to – process delivery requires IP address and port address. The combination of IP
address and port number is called socket address. A transport layer protocol needs a pair of
socket addresses: the client socket address and the server socket address. The IP header contains the IP addresses; the UDP or TCP header contains the port numbers
9/18/2018

7. Multiplexing and Demultiplexing
At the sender site, there may be several processes that need to send packets but there is only one
transport layer protocol. So a multiplexing scheme is required. The protocol accepts messages
from different processes having different port numbers, adds the header and passes the packet to
the network layer.
Demultiplexing
At receiver the data must be delivered to a single process among many through a single transport
layer protocol. So demultiplexing is required. The transport layer receives datagrams from the
network layer, after error checking and dropping of the header, it delivers each message to the
appropriate process based on the port number.
9/18/2018

8. 9/18/2018

9. Connection-less vs. Connection-oriented Service
Connectionless service
In connectionless service there is no need for connection establishment or connection release to send packets from one party to another. The packets are not numbered. There is no
acknowledgement. The packets may be delayed or lost or may arrive out of order. UDP is
connectionless protocol.
Connection-Oriented service
In this service a connection must first be established between sender and receiver the data can be transferred. At the end of communication the connection can be released. TCP and SCTP are connection – oriented protocols.
9/18/2018

10. Reliable vs. Unreliable
If the application layer program needs reliability, we use a reliable transport layer protocol by
implementing flow and error control at the transport layer. The service will be slower and more complex. If the application program does not need reliability because it uses its own flow and error control mechanism or it needs fast service or the nature of the service does not demand flow and error control (real-time applications), then an unreliable protocol can be used. UDP is connectionless and unreliable; TCP and SCTP are connection-oriented and reliable.
9/18/2018

11. USER DATAGRAM PROTOCOL (UDP)
The User Datagram Protocol (UDP) is called a connectionless, unreliable transport protocol.
It does not add anything to the services of IP except to provide process-to-process communication instead of host-to-host communication.
Well known ports for UDP are listed
in the table.
9/18/2018

12. User Datagram Format Source Address Destination Address Length
Checksum
9/18/2018

13. TRANSMISSION CONTROL PROTOCOL (TCP)
TCP is a connection-oriented protocol; it creates a virtual connection between two TCPs to send data. In addition, TCP uses flow and error control mechanisms at the transport level.
Well known ports for TCP are listed
in the table.
9/18/2018

14. DOMAIN NAME SPACE
The domain name space is hierarchical in design. The names are defined in an inverted-tree structure with the root at the top. The tree can have 128 levels: level 0 (root) to level 127.
9/18/2018

15. A domain is a subtree of the domain name space. The name of the
Domains
A domain is a subtree of the domain name space. The name of the
domain is the domain name of the node at the top of the subtree.
9/18/2018

16. RESOLUTION
Mapping a name to an address or an address to a name is called name-address resolution.
DNS is designed as a client-server application. A host that needs to map an address to a name or a name to an address calls a DNS client called a resolver.
Three methods: recursive resolution, iterative resolution and cache.
Cache: when a server asks a mapping from another server and receives the responds, it stores this information in its cache memory before sending to the client. If the same or another client asks for the same mapping, it can check its cache memory and resolve the problem.
9/18/2018

17. another server and waits for the response.
Recursive resolution
The client (resolver) can ask for a recursive answer from a name server.
This means that the resolver expects the server to supply the final answer.
If the server is the authority for the domain name, it checks its database
and responds. If the server is not the authority, it sends the request to
another server and waits for the response.
mcgraw.com
9/18/2018

18. If the client does not ask for a recursive answer, the mapping can be
Iterative resolution
If the client does not ask for a recursive answer, the mapping can be
done iteratively. If the server is an authority for the name, it sends the
answer. If it is not, it returns the IP address of the server it thinks can
resolve the query
mcgraw.com
9/18/2018

19. Acknowledgement : MY SINCERE THANKS TO By Kala H S & Megha Gupta
THE AUTHOR PROF.BEHROUZ A FOROUZAN. BECAUSE THE ABOVE PRESENTATION MATERIALS ARE HEAVILY BORROWED FROM HIS TEXTBOOK “DATA COMMUNICATION & NETWORKING” 4TH EDITION, PUBLISHER TATA MCGRAW HILL
SURESHA V. PROFESSOR, DEPT. OF E&C, KVG COLLEGE OF ENGINEERING. SULLIA, D.K By
Kala H S & Megha Gupta
Assistant Professor
9/18/2018