Internet Protocol Flashcards
Which layer does TCP operate in?
layer 4 (transport layer)
What does TCP do?
enables reliable, connection oriented communication
Which layer does IP sit at?
layer 3 (network layer)
What are protocols at layer 3 designed for?
to be routed across multiple heterogenous networks
What 2 functions does IP implement?
Addressing
fragmentation
What kind of connection is IP?
connectionless protocol
What does connectionless mean?
sends packets to another machine but don’t know if packets will arrive or if in correct order
What is the internet?
Network of networks of computers
why are packets passed between networks?
to reach the destination machine
What does the internet need addresses to specify?
the Machine
the network that machine is on
Why do we need addresses?
to identify a specific computer so we can send data to it
What do addresses in IP need to do?
identify machine uniquely
identify which network machine is on
how are IPv4 addresses formatted?
4 bytes seperated by dots
e.g 192.168.1.1
Whats the problem with IPv4?
Not enough space to store enough addresses
How do we increase the space?
Use IPv6 which increases it to 128 bits
How many IP addresses in class A?
16.7 million addresses per network
1.x.x.x to 127.x.x.x
How many IP addresses in class B?
65536 addresses
128.0.x.x to 191.255.x.x
How many IP addresses in class C?
256 addresses
192.0.0.x - 239.255.255.x
What is class D used for?
multicast
224.0.0.0 to 239.255.255.255
What is class E used for?
reserved
240.0.0.0 to 255.255.255.255
whats the aim of classless inter-domain routing (CIDR)?
to slow ip address space exhaustion
what does CDIR do?
allows variable number of bits to be used to identify network
slow rapid growth of routing tables
what can address configuration be?
configurable or dynamic
What does configurable (static) mean?
you specify IP address
What does dynamic mean?
Computer automatically allocated address
what is the max size of IP packet on ethernet?
1500 bytes
What is the max size of IP packet known as?
Maximum transmission unit (MTU)
What is time to live (TTL) field in IPv4 packet used for?
to avoid packets ending up in loop as routes to destination can change at any moment even while packet is in transit
How does TTL work?
each router decrements TTL
if it = 0 packet is discarded
Why are IP packets fragmented?
they are passed between different networks
may have different packet sizes
How does fragmentation work?
data in IP packet split into chunks
these are then sent as IP packets across other network
identification field used to identify packet
Fragment offset used to specify where data goes
Receiver puts fragments back together to regenerate the original packet
How big is each chunk?
multiple of 8 bytes long
Does IPV6 use fragmentation?
no rather it finds out largest packet size allowed on path between 2 machines
then uses as its MTU for sending packets
