Chapter 1 Flashcards
(31 cards)
Distributed Applications
apps which involve multiple end systems exchanging data with each other.
Host vs. End-System
interchangeable terms for the agents that operate within the internet
Access Technology Examples
- DSL
- Cable
- Fibre
- 3G
- LTE
- Ethernet
- Wifi
Guided Media vs. Unguided Media
solid medium vs. WLAN or satellite
What speeds of Ethernet LAN are there?
10 Mbps, 100 Mpbs, 1 Gbps, 10 Gbps
Max speeds of access technologies
up to 56 Kbps, bandwidth is dedicated; ADSL: up to 24 Mbps downstream and 2.5 Mbps upstream, bandwidth is dedicated; HFC, rates up to 42.8 Mbps and upstream rates of up to 30.7 Mbps, bandwidth is shared. FTTH: 2-10Mbps upload; 10-20 Mbps download; bandwidth is not shared.
What is store-and-forward?
every packet must be received in a node before being transmitted to a subsequent node.
Output buffer/queue
stores all outgoing packets before sending them.
Queuing Delay
a delay caused by waiting for a busy link and being stored in a output buffer. can lead to lost packets if it runs out of space.
Forwarding Table
maps destination addresses to the router’s outbound link.
Packet Switch vs. Circuit Switch
packet switch involves a shared medium, where a request/response is important. circuit switch is a direct line between two communicators - more resource heavy, but direct and dependable, with a guaranteed bandwidth.
Circuit
When two end users on a network maintain a persistent connection throughout their communication.
FDM
Frequency-division multiplexing.
TDM
Time-division multiplexing.
What are the delay components of a packet sending action?
- processing delay
- transmission delay
- propagation delay
- queueing delay
Define processing delay
time required to examine a packet’s header and determine where it goes
Define transmission delay
it is L/R where L is the length in bits and R is the transmission rate.
define propagation delay
Physical movement delay, dependent on the medium. usually between 2e8 m/s or 3e8m/s speed of lightish. it is d/s where d is the distance and s is the speed.
define queueing delay
the delay a packet experiences while it waits to be transmitted onto the link.
name the layers
application layer transport layer network layer link layer physical layer
application layer
where the network applications reside. includes HTTP, SMTP, and FTP. uses DNS. packets are called a MESSAGE
transport layer
Transports application-layer messages between app endpoints. Uses TCP and UDP. Packets are called a SEGMENT
network layer
Uses the IP protocol to move packets from one host to another. Contains the routing protocols. Packets are called DATAGRAMS.
link layer
Interfaces between the network and physical layer - prepares the DATAGRAM for delivery from the current link to the next link. Ethernet, WiFi are examples of link layer. packets are called FRAMES.
