Cellulära nät och IoT Flashcards
What is an example of a problem with telecommunication network?
- In a typical host/user data connection, the medium is often idle, unused.
- In a circuit-switching network, the connected devices need to transmit/recieve data at tthe same rate.
What is an upside to packet-switching compared to circuit-switching?
- There’s greater line efficiency, dynamic routing.
- Can perform data rate conversions.
- Under heavy traffic, the flow of data is slowed down, but not halted completely.
- Packets can have different priority from each other.
What are the two switching techniques?
When is one preferred to the other generally?
- A datagram approach treats each packet independetly from the others. This means they’ll take different paths and arrive at different times. The routers make up decisions on the spot on where to send the packets.
- A virtual circuit approach has all packets being sent along a pre-planned route, similiar to circuit switching, but the route is not set in stone.
Longer data exchanges usually prefer a virtual circuit.
Why do we send data in small packets?
- Easier to check for errors.
- Quicker to transmit.
- Gives flexibility for routing.
- Can easily be standardized.
How do you compare the performance of a circuit switch, to a virtual circuit switch with pakets, with a datagram packet switching?
A circuit switch takes a while to set up, and then transmits continously.
A virtual circuit takes a while to set up and looks similiar to a circuit switch.
A datagram packet takes no time to set up, but the packets have node delay since they are not routed beforehand.
What are end systems and intermediate systems in networks?
ES & IS
An end system is a device, like a server or laptop which is attached to the network.
The networks are connected by devices refered to as intermediate devices. (routers and switches).
What is DHCP? What is it used for.
(hint: host configuration protocol)
DHCP stands for dynamic host configuration protocol. It’s an IP with the ability to dynamically assign IP addresses to hosts. It was invented to deal with IP shortages since IPv4 is limited.
It’s also useful for mobile systems (phones, tablets) which travel among different networks.
Is the IP header attached to the datagram before or after LLC?
The network layer is attached before the LLC since the network layer is above the data link layer.
If end system A wants to send to end system B in a different network, where will the MAC address point? What will the IP be?
-The MAC address will point to the router connecting the networks as that’s where the datagram is heading.
-The IP header will be focused on the final destination, the IP of end system B.
Why do we use fragmentation when sending datagrams?
Different networks have different standards, dividing the packet into smaller pieces means it can pass different standards.
What is a DHCP server?
A server which provides available IP addresses upon a DHCP request.
What is HTTP?
HTTP stands for Hypertext transfer protocol and is the foundation protocol for the WWW, used by all clients/server involving hypertext. The data transfered can be plaintext, audio etc.
What is a proxy?
A proxy is a forwarding agent, forwarding URL requests.
What is a gateway?
A gateway is a server which acts on behalfs of other server which can not communicate with the client directly.
What is a tunnel?
Simply a relay point between two TCP connections. No changes are done.
