Flashcards
Routing and addressing
Cards in this deck (9)
- 1What is forwarding and routing?forwarding: refers to the router-local action of transferring the packet from an input link interface to the appropriate output link interface.
Routing: refers to the network-wide process that determines end-to-end paths that packets take from source to destination. - 2What is a forwarding table?Every router has one. A packet is examined by checking its header & using a value there to index into the table. The value in the table indicates the router's outgoing link interface
- 3what does MTU stand for?Maximum transition unit -
the largest size packet or frame, specified in octets (eight-bit bytes), that can be sent in a packet- or frame-based network such as the Internet - 4What type of problem with MTU does fragmentation solve?Each link have different MTU's, if one link has a smaller than the other, we might have problems sending a certain package.
This is solved with IP fragmentation which involves breaking a datagram into a number of pieces that can be reassembled later (at the end system). - 5How does fragmentation work?You use a flag and a an offset.
The flag is 0 or 1, 0 indicating that that it is the last piece. 1 indicating that more pieces are coming.
Offset shows where the piece should be inserted when the pieces are reasembled. It is given in byte.
For ex: offset 370 means that you should insert the piece at bit 370*8 = 2960 - 6What does an "interface" refer to in addressing?It is the boundary between host & physical link. Routers can have multiple interfaces, each for every link.
OBS - in IPv4 each interface has its own IP-address - 7What is CIDR and what is it used for?Classless InterDomain Routing (CIDR) was invented to keep the Internet from running out of IP Addresses.
- 8How do we address in a subnetwork?- Every subnet has a ”network address”
- The remaining bits are used to address hosts
- Every interface (including router!) has its own IP address
- One address per subnetwork is used for broadcast (all 1’s in the host part) - 9If we write a IP address like this: 216.3.128.12/25 What does /25 stand for?The number next to the slash (i.e. /25) represents the number of bits assigned to the network address. Which in this case leaves 32-25 bits to the address the host in the network
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- Datakomm Flashcards on Routing and addressing, created by Emma Tysk on 12/11/2017.
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- Emma Tysk
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