Outubro 2008
Prof. Ismael H. F. Santos
- ismael@tecgraf.puc-rio.br
2
Design Strategies (Cont.)
nTransport layer –
responsible for low-level network access
and for message transfer between clients, including partitioning messages into packets,
maintaining packet
order, controlling flow, and generating physical addresses.
nSession layer –
implements sessions, or process-to-process
communications protocols.
nPresentation layer – resolves the differences in formats among the various sites in the network, including
character conversions, and half
duplex/full duplex (echoing).
nApplication layer
– interacts directly with the users’ deals with file transfer, remote-login protocols and
electronic mail, as well as
schemas for distributed databases.