The User Datagram Protocol

Published Date: 02 Nov 2017

User Datagram Protocol (UDP)

The Internet provides two services to its applications: a connection oriented reliable service TCP or a connectionless unreliable service UDP. Depending on the nature of the application (reliable information or unreliable information).

TCP: the connection oriented reliable service guarantees that data transmitted from a sender to a receiver will eventually be delivered to the receiver in order and in its entirety.

UDP: The connectionless unreliable service does not make any guarantees about eventual delivery.

TDM and FDM are multiple access techniques used for multiplexing number of signals into a single for bandwidth.

The advantage of FDM over TDM is in the time that takes for data to reach its destination (latency).

The TDM works with periods of time, can transmit only one channel at a certain time, and some of data are often delayed, while the channels in FDM can transmit at any time. Latency time is much lower as compared to TDM.

FDM is often used at applications which latency is of nearly priority like those that requires real time information.

The Ethernet usually runs over twisted-pair, copper wire. Also can run over Coaxial Cable, Fiber Optics, Terrestrial Radio Channels, and Satellite Radio Channels.

range of transmission rates

bandwidth

Dial-up

Up to 56

dedicated

ISDN

Up to 128

dedicated

DSL

Up to 8Mbps downstream

Up to 1Mbps upstream

dedicated

HFC

Up to 30 Mbps downstream .

2Mbps upstream

shared

The delay components are four:

Nodal processing: constant.

Queuing: fixed, depends on queuing algorithm, traffic type and congestion.

Transmission: Constant, depends on packet size and link capacity.

Propagation: Constant, has a fixed route

In the Virtual circuit network, the exchange of information happens in custom path between the source and the destination, and each path is given a number of active virtual circuits.

the routers here needs to maintains information on this path which is interface data coming from specific interface to be redirected. This is called the connection state information.

Each time a new connection is established, the "connection status information" should be updated in the routing table, and each time the connection of exchange data completes, the "connection status information" should be discarded.

briefly, the connection status information is the information needed, which is the maintained by the router to redirect data to the correct interface, for an active connection.

Network layer by making a decision based on IP addresses, the router process layers are typically three (network, data link and physical layers).

For a process on one host to identify a process on another host, the sending process must identify the receiving process. To do that, must specify two pieces of information

The IP address of the destination host

And the port number of the destination socket

The protocol uses handshaking if the two communicating entities, firstly they exchanging control packets before transmitting data to each other.

in another way, When a computerA connects to computerB, the first thing must do is contact computerB and asking for identify and than for connect. than the ComputerB must decide to accept, deny or ignore. and than the connection tells ComputerB about the connection state, (accepted, denied or ignored).

E.g : SMTP uses handshaking at the application layer, while HTTP does not

because, all of this applications associated with these protocols require that all application data must be received in the correct order and without gaps or loss data. TCP provides this service, while UDP not.

Because the control information is not sending over the same connection which the file is sent over.

FTP sends control information out of band.

Yes, an application developer can put reliable data transfer in the application layer protocol. This requires a great deal of work and corrections..

first segment contains = 220 –101 = 119 bytes.

R / 2 because of relatively property of the TCP protocol. Thus, both should have the same connections rate.

As known that the role of the network layer is to move packets from sending to receiving host.

The two main functions of the datagram-based network layer are:

1. Routing / Path determination: The network layer determining the path or route taken by packets as it flow from the sender to the receiver.

2. Forwarding: When a packet arrives to the router's input, the router must move a packet to the appropriate output link. (From router’s input to appropriate router output).

The additional function of a VC-based network is call setup.

The OSPF advertisement is using the Link state algorithm, A router periodically broadcasts routing information to the another routers in the AS, it's not just to the neighboring routers.

This routing information sent by a router has one entrance for each of the router’s neighbors; the entry gives the distance from the router to the neighbor.

The RIP advertisement is using Distance Vector Algorithm, it sent by routers that contain an information about all the networks in the AS, although this information is just sent to its neighboring routers.

Switching through memory

1. Packets copied by systems "CPU".

2. Speed limited by memory bandwidth.

• b. Switching through bus.

1. Datagram from input port memory into output port memory through a shared bus.

2. Bus contention: switching speed is limited by bus bandwidth.

• c. Switching through an interconnection network.

1. Overcome bus bandwidth limitation.

2. Banyan networks, other interconnection networks developed initially to connect a processors in multiprocessor.

3. Advanced designing: fragmenting datagram into the fixed-length cells and switching cells via fabric.

The Main changes are:

Larger addresses. The addresses size changes from 32 bits to 128 bits

Extended Address Hierarchy. IPv6 uses the larger address spece to create additional levels of addressing hierarchy.

Flexible Header Format.

Improved Options.

Provision for protocol extension

Support for auto-configuration and renumbering

Support for Resource allocation.

The following table listing the differences between IPv4 and IPv6.

IPv4 

IPv6

IPv4 address is 32 bit length

IPv6 address is 128 bit length

IPsec support is optional only

Inbuilt IPSec support

The Fragmentation are done by sender and forwarding routers

Fragmentation is done by sender only

There is no packet flow identification

Packet flow identification is available in the IPv6 header using a flow label field

Checksum field is an available in header

No checksum field in the header

Option fields are available in the header

No option fields. But Extension header is available

ARP is available to map IPv4 addresses to MAC addresses

ARP is replaced with Neighbor Discovery Protocol

IGMP is uses to manage multicast group membership

IGMP is replaced with Multicast Listener Discovery (MLD) message

Broadcast message is available

Broadcast messages are not available

Manual configuration of IP addresses "Static" or "DHCP" Dynamic configuration is required to configure IP addresses

Auto configuration of IP addresses are available

1^0^1^0^1^0^1^0^1^0^1^0^1^0^1^1 = 1

10101010101010111

There would be a collision, which means when a node is transmitting, it will begin to receive another packet from other node.

Lan = 248 MAC addresses; IPv4 = 232 IPv4 addresses; IPv6 = 2128 IPv6 addresses

Lan = 48 bit

IPv4 = 32 bit

IPv6 = 128 bit

Services that a link-layer protocol can offer to the network layer are

Framing: there is framing in IP and TCP too.

Reliable delivery: there is reliable delivery in TCP.

Link access.

Flow control: there is flowing control in TCP too.

Error correction.

Error detection: there are error detections in IP and TCP.

Full duplex: in TCP also there is Full duplex.

The main important difference is the transmission speeds, which are 10, 100 and 1000 Mbps per seconds, Both 10BaseT and 100BaseT Ethernet use a star topology, while Gigabit Ethernet use the standard Ethernet frame format.

• 802.3i 1990 10BASE-T 10 Mbit/s (1.25 MB/s) over twisted pair

• 802.3u 1995 100BASE-TX, 100BASE-T4, 100BASE-FX Fast Ethernet at 100 Mbit/s (12.5

MB/s) w/autonegotiation

• 802.3ab 1999 1000BASE-T Gbit/s Ethernet over twisted pair at 1 Gbit/s (125 MB/s)

End-to-end delay is the time that takes the packet to travel over the network from a source to destination.

Delay jitter is the fluctuation of end-to-end delay from packet to the next packet.

Jitter is the variation in the time between packets arriving (packet transit delay), causes by queuing, network congestion, timing drift, route changes and contention and serialization effects on the path through the network.

Answer:

When a node transmits a frame, the node has to wait for the frame to propagate around the entire ring before the node can release the token. Thus, if L/R is small as compared to tprop, then the protocol will be inefficient.

Answer:

Streaming stored audio/video: pause/resume, re-positioning and fast-forward.

Real-time interactive audio and video: people communicating and responding in real time.