25-05-2012, 02:27 PM
William Stallings Data and Computer Communications
William StallingsData and Computer Communications.ppt (Size: 457.5 KB / Downloads: 17)
Characteristics
Direct or indirect
Monolithic or structured
Symmetric or asymmetric
Standard or nonstandard
Direct or Indirect
Direct
Systems share a point to point link or
Systems share a multi-point link
Data can pass without intervening active agent
Indirect
Switched networks or
Internetworks or internets
Data transfer depend on other entities
Monolithic or Structured
Communications is a complex task
To complex for single unit
Structured design breaks down problem into smaller units
Layered structure
Standard or Nonstandard
Nonstandard protocols built for specific computers and tasks
K sources and L receivers leads to K*L protocols and 2*K*L implementations
If common protocol used, K + L implementations needed
Segmentation
Data blocks are of bounded size
Application layer messages may be large
Network packets may be smaller
Splitting larger blocks into smaller ones is segmentation (or fragmentation in TCP/IP)
ATM blocks (cells) are 53 octets long
Ethernet blocks (frames) are up to 1526 octets long
Checkpoints and restart/recovery
William StallingsData and Computer Communications.ppt (Size: 457.5 KB / Downloads: 17)
Characteristics
Direct or indirect
Monolithic or structured
Symmetric or asymmetric
Standard or nonstandard
Direct or Indirect
Direct
Systems share a point to point link or
Systems share a multi-point link
Data can pass without intervening active agent
Indirect
Switched networks or
Internetworks or internets
Data transfer depend on other entities
Monolithic or Structured
Communications is a complex task
To complex for single unit
Structured design breaks down problem into smaller units
Layered structure
Standard or Nonstandard
Nonstandard protocols built for specific computers and tasks
K sources and L receivers leads to K*L protocols and 2*K*L implementations
If common protocol used, K + L implementations needed
Segmentation
Data blocks are of bounded size
Application layer messages may be large
Network packets may be smaller
Splitting larger blocks into smaller ones is segmentation (or fragmentation in TCP/IP)
ATM blocks (cells) are 53 octets long
Ethernet blocks (frames) are up to 1526 octets long
Checkpoints and restart/recovery