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21 Cards in this Set
- Front
- Back
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Communication at the network layer |
layer accepts packet from transport layer, encaps the packet in the datagram and delivers to DLL |
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Packetizing? |
Encapsulates payload in a network-layer packet at the source Decaps payload from the NL packet at destination source adds a header |
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header contains... |
source and destination address |
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Routers do what in the path? |
not allowed to decap unless packets need fragmentation. only inspect the addresses for the purpose of forwarding |
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forwarding? |
the action applied by each router when the packet arrives at one of its interfaces |
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Forwarding table? |
forwarding value and output interface |
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4 other services? |
1. flow control 2. congestion control 3. quality of service 4. security |
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IPv4 Address Space? |
2^32 = approx 4 billion |
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address are unique and universal. what does this mean? |
two devices on the internet can never have the same address at the same time |
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3 common notations of addresses? |
1. binary 2. dotted-decimal 3. hex |
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Classful addressing 5 classes? |
A B C D and E |
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Class A? |
large organisation with large numbers of hosts or routers |
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class B |
midsize org with ten or thousands of host and routers |
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class C |
small org with small number of hosts or routers |
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Net Id and Host Id |
net - first 3 octets host - last octet of IP address |
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mask in classless addressing |
x.y.z.t /n /n - mask |
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number of address |
2^32-n |
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network addresses? |
represents the organisation to the rest of the world |
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subnet |
cluster of networks |
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NAT |
network address translation - enable users to have a large set of addresses internally, and one address externally. |
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Translation table |
used for exchanges. all outgoing packets got through NAT router which replaces source address with global NAT address |
