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Routers use the Internet Protocol (IP)
address information in an IP packet header to determine which
interface the packet should be switched to in order to move closer
its destination. Because IP does not provide any services to help
insure that the packet actually reaches the destination, it is
described as an unreliable, connectionless protocol, using
best-effort delivery. If packets are dropped in route, arrive in
the wrong order, or are transmitted faster than the receiver can
accept them, IP alone cannot correct the problem. To address these
problems, IP relies upon Transmission Control Protocol (TCP). This
module describes TCP and its functions and introduces UDP, another
important Layer 4 protocol. Each layer within the OSI
networking model has various functions. These functions are
independent of the other layers. Each layer expects to receive
services from the layer beneath it, and each layer provides
certain services to the layer above it. The application,
presentation, and session layers of the OSI model, which are all
considered to be part of the application layer in the TCP/IP
model, access the services of the transport layer through logical
entities called ports. This module will introduce the concept of
ports and will explain the critical importance of ports and port
numbers in data networking.
Students completing this module
should be able to:
- Describe TCP and its function
- Describe TCP synchronization and
flow control
- Describe UDP operation and
processes
- Identify common port numbers
- Describe multiple conversations
between hosts
- Identify ports used for services
and clients
- Describe port numbering and well
known ports
- Understand the differences and
the relationship between MAC addresses, IP addresses, and port
numbers
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