CSE 3461 Midterm Exam
nodal processing delay check bit errors
determine output link
typically < msec
Queuing Delay - time waiting at output link for transmission
- depends on congestion level of router
Transmission Delay the amount of time required to push all of the packet's bits into the link (L/R)
Link Bandwidth Variable Name R
Packet Length Variable Name L
Propagation Delay any delay in communications from signal transmission time through a physical
medium
Propagation Delay Formula d/s
Length of physical link variable name d
Propagation speed variable name s
Average Packet Arrival Rate Variable Name a
Traffic Intensity Formula La/R
What happens when traffic intensity approaches 1? Delays become large
Internet Protocol Stack Application
Transport
Network
Link
Physical
Application Layer Supports network applications
Transport Layer Host-host data transfer
Network Layer routing of datagrams from source to destination (IP, routing protocols)
, CSE 3461 Midterm Exam
Link Layer data transfer between neighboring network elements
Physical Layer bits "on the wire", "over the air"
Purpose of Network Applications Run on (different) end systems, communicate over network
Process Program running within a host
Socket How process sends/receives messages, composed of IP address and port
number
App-layer protocol defines Types of messages exchanged
Message syntax
Message semantics
Rules for when and how processes send & respond to messages
What transport service does an app need? - Data integrity
- Timing
- Throughput
- Security
Browser User agent for the Web
HTTP Web's application layer protocol
Is HTTP stateless or stateful? Stateless
Web caching Satisfy client request without involving origin server
Why use web caching? Reduce response time for client request, reduce traffic, Internet dense with
caches
Conditional GET don't send object if cache has up-to-date cached version
FTP File transfer to/from remote host
FTP Port Number 21
nodal processing delay check bit errors
determine output link
typically < msec
Queuing Delay - time waiting at output link for transmission
- depends on congestion level of router
Transmission Delay the amount of time required to push all of the packet's bits into the link (L/R)
Link Bandwidth Variable Name R
Packet Length Variable Name L
Propagation Delay any delay in communications from signal transmission time through a physical
medium
Propagation Delay Formula d/s
Length of physical link variable name d
Propagation speed variable name s
Average Packet Arrival Rate Variable Name a
Traffic Intensity Formula La/R
What happens when traffic intensity approaches 1? Delays become large
Internet Protocol Stack Application
Transport
Network
Link
Physical
Application Layer Supports network applications
Transport Layer Host-host data transfer
Network Layer routing of datagrams from source to destination (IP, routing protocols)
, CSE 3461 Midterm Exam
Link Layer data transfer between neighboring network elements
Physical Layer bits "on the wire", "over the air"
Purpose of Network Applications Run on (different) end systems, communicate over network
Process Program running within a host
Socket How process sends/receives messages, composed of IP address and port
number
App-layer protocol defines Types of messages exchanged
Message syntax
Message semantics
Rules for when and how processes send & respond to messages
What transport service does an app need? - Data integrity
- Timing
- Throughput
- Security
Browser User agent for the Web
HTTP Web's application layer protocol
Is HTTP stateless or stateful? Stateless
Web caching Satisfy client request without involving origin server
Why use web caching? Reduce response time for client request, reduce traffic, Internet dense with
caches
Conditional GET don't send object if cache has up-to-date cached version
FTP File transfer to/from remote host
FTP Port Number 21
