Network Architectures Professor Jinhua Guo CIS 527 Fall 2002
Layering Use abstractions to hide complexity Abstraction naturally lead to layering Application programs Hardware Host-to-host connectivity Process-to-process channels
Alternative abstractions at each layer Request/reply channel Message stream channel Application programs Hardware Host-to-host connectivity
Protocols Building blocks of a network architecture Each protocol object has two different interfaces –service interface: operations on this protocol –peer-to-peer interface: messages exchanged with peer Term “protocol” is overloaded –specification of peer-to-peer interface –module that implements this interface
Host 1 Protocol Host 2 Protocol High-level object High-level object Service interface Peer-to-peer interface Interfaces
Protocol Graph –collection of protocols and their dependencies –most peer-to-peer communication is indirect –peer-to-peer is direct only at hardware level File application Digital library application Video application RRPMSP HHP Host 1 File application Digital library application Video application RRPMSP HHP Host 2
Multiplexing and Demultiplexing (demux key) Encapsulation (header/body) RRPDataHHP Application program Application program Host 1Host 2 Data RRP Data HHP Data RRP Data HHP
Standard Architecture Open Systems Interconnection (OSI) Architecture –Internation Standards Organization (ISO) –International Telecommunication Union (ITU) formerly CCITT –“X dot” series: X.25, X.400, X.500, … –Reference Model
ISO Architecture Application Presentation Session Transport End host One or more nodes within the network Network Data link Physical Network Data link Physical Network Data link Physical Application Presentation Session Transport End host Network Data link Physical
Internet Architecture Defined by Internet Engineering Task Force (IETF) Application vs Application Protocol (FTP, HTTP) … FTPHTTPNV TFTP TCP UDP IP NET 1 2 n
TCPUDP IP Network Application Does not imply strict layering Hourglass shape Implement as you go Features of Internet Architecture