Routing Flashcards
(28 cards)
Which layer does routing take place?
layer 3
What is a router?
computer/machine set up to route packets
What does router do?
examines packet to see which is best place to send it next to reach the destination
Whats an advantage of routing?
traffic between networks massively reduced
What is the store and forward?
router fully receives the packet
before then sending it out on the destination network
why does router need memory?
to buffer packets as they arrive before sending them out
What happens to data?
rewrapped into different layer 2 packets
do networks need to be the same type anymore?
no
How does the connection work for router?
multiple ways
can be via long point-to-point link
Does router need to be directly connected to destination network?
no it can send to second router which is connected to that network instead of direct
Where do layer 3 packets need to be delivered?
destination machine (specify both machine and nework for each packet)
why do we need routing table?
tells us how to send each packet
What does routing table store?
since computer dont need to know whole path we only store the next hop
What is meant by next hop?
address of next machine to send it to
What does each routing table do?
maps a destination address to the next hop
How does next hop routing work?
computer looks up next hop for a particular destination and sends packet to it via network connection
What happens if receiving machine isnt destination?
it looks up in routing table what the next hop is for destination
What is source independence?
next hope is entirely dependent on destination not packets source
Does routing table contain details for every machine?
No for same destination network machines will share the same next hop
so what does routing table need to store?
network prefix part of address
What are default routes?
routes that are identical and these are used by default unless there is a more specific route
advantage of default routes?
reduces size of routing table
what should routing table guarantee?
Universal, optimal routing
How are networks in routing table specified?
in terms of IP address on network and netmask
