Exam 2 Flashcards
(29 cards)
What are the 3 different types of switching fabric
memory
bus
crossbar
explain network neutrality
and what are the mechanisms that affect network neautrality
all data on the internet should be treated equally.
companies cant pay to have their competitors data throttled
packet scheduling and buffer management are the mechanisms
what are the 5 layers of the network stack
application
transport
network
link
physical
what are the general principles of distributed systems
distributed
decentralized
scalable
fault tolerant
what are the 2 key network layer functions
forwarding and routing
what is forwarding
moving a packet from a router’s input link to the appropriate router output link
what is routing
determine route taken by packets from source to destination
forwarding vs routing
forwarding is like going through a single intersection
routing is like planning a cross country road trip
what is Dynamic Host Configuration Protocol
DHCP
How a device can get a ip address from a network server when it “joins” the network
what is Network Address Translation
NAT
all devices in a local network share just one ip address as far as the outside world is concerned
all datagrams leaving local network have the same source NAP IP address but different source port numbers
what is the main advantage of NAT
just 1 ip address needed from provider ISP for all devices on the network
what are the components of packet processing
prefix matching and routing decisions
what happens inside a router
packet processing
crossing the switching plane
buffering
scheduling
what are different approaches to packet scheduling
FIFO or other algorithms
Prioritization
- can be multi leveled
- different priority weights
- round robin
what is a subnet
device interfaces that can physically reach each other without passing through an intervening router
devices in the same subnet have common high order bits
the host part is the remaining low order bits
a.b.c.d/x where x is the # bits in subnet portion
what are the 2 different formats for ip address
and what are their sizes
IPv4 - 32 bits
IPv6 - 128 bits
link layer services
adjacent device to device communication
flow control
error detection
error correction
-> 2 dimensional error correction
general implementation of dht
finger table <hashed key, peer address>
[ fingers, next, self, prev ]
local hash table <hashed key, byte array>
explain the locate protocol in our DHT
ask a person in the DHT if they own a hashed key
the person will return the person closest to that hashed key or maybe they own the hashed key in which case they would return themselves
what is address resolution protocol
ARP
ARP is how a device determines what MAC address corresponds to a ip address
sends out ARP request
the request is broadcasted to everyone and the person who has the ip address responds
a benefit is now everyone knows the mac address for the person who initiates the request
broadcast vs unicast
broadcast goes from one source to all
unicast goes from one source to one receiver
explain prefix matching
when looking for forwarding table entry for given destination address, use longest address prefix that matches destination address
Prefix matching is a technique used primarily in routing to determine which path a packet should take based on the longest matching prefix of its destination IP address.
what is tunneling
IPv6 datagram carried as payload in IPv4 datagram among IPv4 routers
what was the motivation to create / change to IPv6
32-bit IPv4 address space would be completely allocated
