Lesson 2 Flashcards
ARPANet connects what together
big academic computers
1982 DNS went from host files to distributed (T/F)
True
How many bits are in an IPv4 address
32
Growing Pains of Internet
1) IPv4 only 32 bits, we are running out
2) Congestion control - insufficient dynamic range
3) Routing - no security, easily misconfigured, poor convergence, non-determinism (sorta works)
4) Security - we are not good at turning it on and we don’t encrypt
5) DoS - internet will transmit packets even if victim does not want them
narrow waist allows …
interconnecting of many existing networks where all devices speak “IP” (the network layer, layer 3)
Packet Switching (PS) vs Circuit Switching (CS): PS has busy signals
No - circuit switching does
Packet Switching (PS) vs Circuit Switching (CS): CS has dedicated resources
Yes, circuit switching has dedicated resources
Packet Switching (PS) vs Circuit Switching (CS): CS shared network resources
no Packet Switching does
Advantages of Packet Switching over Circuit Switching
Packet Switching shares network resources, does not have busy signals
Advantages of Circuit Switching over Packet Switching
Circuit Switching maintains dedicated resources
Network layers (bottom to top, 5 of them) and their purpose
1 - physical layer - devices 2 - ethernet (link layer) - p2p 3 - IP (network layer) - narrow waist 4 - Transport layer - e2e connectivity 5 - Application layer (reliable transport, congestion control)
Explain the principal of Survivability
- network should continue to work even if devices fail
- replication
- fate sharing
Explain Fate Sharing
it’s acceptable to lose state info - if the router crashes all state on the router (router table for example) is lost
Does NAT violate Fate Sharing
Yes
BGP
Border Gateway Protocol - how all the ASes figure out how to take a packet and transmit it to other ASes (or keep it for internal processing) - helps the routers of the ASes to build the router tables based on distances and tie breakers
