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Temat artykułu: Connection-oriented vs. Connectionless Communication
Tekst napisał pitt2k dnia 08-01-2004
Connection-oriented service involves three phases:
Call Setup
During the connection establishment phase, a single path between the source and destination systems is determined. Network resources are typically reserved at this time to ensure a consistent grade of service (such as a guaranteed throughput rate).
Data transfer
During the data transfer phase, data is transmitted sequentially over the path that has been established. Data always arrives at the destination system in the order it was sent.
Call termination
During the connection termination phase, an established connection that is no longer needed is terminated. Further communication between the source and destination systems requires a new connection to be established.
Connection-oriented service has two significant disadvantages as compared to a connectionless network service:
Static path selection
Because all traffic must travel along the same static path, a failure anywhere along the path causes the connection to fail.
Static reservation of network resources
A guaranteed rate of throughput requires the commitment of resources that cannot be shared by other network users. Unless full, uninterrupted throughput is required for the communication, bandwidth is not used efficiently.
Connection-oriented services are useful for transmitting data from applications that are intolerant of delays and packet re-sequencing. Voice and video applications are typically based on connection-oriented services.
REMEMBER THIS !!!
Positive acknowledgement requires packets to be retransmitted if an acknowledgement is not received by the time a timer expires.
Know that subnetting takes place in the Network layer of the OSI model.
Know the 3 phases of connection oriented communication.
Know that a disadvantage to using a connection oriented protocol is that packet acknowledgement may add to overhead.
Connectionless communication is supported by UDP on port 17. It is not guaranteed and acknowledgements are NOT sent or received. It is faster than connection orientated. It is up to the application or higher layers to check that the data was received.
Connectionless network service does not predetermine the path from the source to the destination system, nor are packet sequencing, data throughput, and other network resources guaranteed. Each packet must be completely addressed because different paths through the network might be selected for different packets, based on a variety of influences. Each packet is transmitted independently by the source system and is handled independently by intermediate network devices.
Connectionless service offers two important advantages over connection-oriented service:
Dynamic path selection
Because paths are selected on a packet-by-packet basis, traffic can be routed around network failures.
Dynamic bandwidth allocation
Bandwidth is used more efficiently because network resources are not allocated bandwidth that they are not going to use. Also, since packets are not acknowledged, overhead is reduced. Connectionless services are useful for transmitting data from applications that can tolerate some delay and re-sequencing. Data-based applications are typically based on connectionless service.
REMEMBER THIS !!!
Bandwidth requirement and overhead traffic are reduced because packets are not acknowledged in a connectionless environment.
UDP is unreliable and unacknowledged.
Opracowanie na podstawie materiałów TroyTech (www.troytech.com).
Temat artykułu: Connection-oriented vs. Connectionless Communication
Tekst napisał pitt2k dnia 08-01-2004
Connection-orientated
Connection oriented communication is supported by TCP on port 6. It is reliable because a session is guaranteed, and acknowledgements are issued and received at the transport layer. This is accomplished via a process known as Positive Acknowledgement. When the sender transmits a packet a timer is set. If the sender does not receive an acknowledgement before the timer expires, the packet is retransmitted.Connection-oriented service involves three phases:
Call Setup
During the connection establishment phase, a single path between the source and destination systems is determined. Network resources are typically reserved at this time to ensure a consistent grade of service (such as a guaranteed throughput rate).
Data transfer
During the data transfer phase, data is transmitted sequentially over the path that has been established. Data always arrives at the destination system in the order it was sent.
Call termination
During the connection termination phase, an established connection that is no longer needed is terminated. Further communication between the source and destination systems requires a new connection to be established.
Connection-oriented service has two significant disadvantages as compared to a connectionless network service:
Static path selection
Because all traffic must travel along the same static path, a failure anywhere along the path causes the connection to fail.
Static reservation of network resources
A guaranteed rate of throughput requires the commitment of resources that cannot be shared by other network users. Unless full, uninterrupted throughput is required for the communication, bandwidth is not used efficiently.
Connection-oriented services are useful for transmitting data from applications that are intolerant of delays and packet re-sequencing. Voice and video applications are typically based on connection-oriented services.
REMEMBER THIS !!!
Positive acknowledgement requires packets to be retransmitted if an acknowledgement is not received by the time a timer expires.
Know that subnetting takes place in the Network layer of the OSI model.
Know the 3 phases of connection oriented communication.
Know that a disadvantage to using a connection oriented protocol is that packet acknowledgement may add to overhead.
Connectionless-orientated
Connectionless communication is supported by UDP on port 17. It is not guaranteed and acknowledgements are NOT sent or received. It is faster than connection orientated. It is up to the application or higher layers to check that the data was received.
Connectionless network service does not predetermine the path from the source to the destination system, nor are packet sequencing, data throughput, and other network resources guaranteed. Each packet must be completely addressed because different paths through the network might be selected for different packets, based on a variety of influences. Each packet is transmitted independently by the source system and is handled independently by intermediate network devices.
Connectionless service offers two important advantages over connection-oriented service:
Dynamic path selection
Because paths are selected on a packet-by-packet basis, traffic can be routed around network failures.
Dynamic bandwidth allocation
Bandwidth is used more efficiently because network resources are not allocated bandwidth that they are not going to use. Also, since packets are not acknowledged, overhead is reduced. Connectionless services are useful for transmitting data from applications that can tolerate some delay and re-sequencing. Data-based applications are typically based on connectionless service.
REMEMBER THIS !!!
Bandwidth requirement and overhead traffic are reduced because packets are not acknowledged in a connectionless environment.
UDP is unreliable and unacknowledged.
Opracowanie na podstawie materiałów TroyTech (www.troytech.com).