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25 Cards in this Set
- Front
- Back
Nodal Delay |
Delay between nodes on a network |
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processing delay |
The time it takes for routers to process packet headers |
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transmission delay |
The amount of time it takes to push all of the packet bits into the wire. |
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queueing delay |
Delay created when packets arrive faster than they can be processed. Router queues them for processing. |
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propogation delay |
Time it takes for signal to travel from one destination to another. |
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packet switching |
Divides communications into packets that are transmitted individually, in contrast to circuit switching. |
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circuit switching |
Dedicated communications channel is established for the duration of the transmission. |
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network layer |
Handles communication between nodes that may not be directly connected. |
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addressing and routing at network layer |
Addressing - addresses on other networks may not match. Network layer handles this.
Routing - figure out the best path between nodes |
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IPv4 vs IPv6 |
IPv4 - 32 bit dotted decimal format
IPv6 - 128 bit hexadecimal separated by colons |
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Transport Layer |
Provides process to process communications. Provides TCP and UDP. |
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port numbers |
docking points for software / programming so a socket can be created and data can be transferred between two computers |
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TCP |
Transport layer protocol. Reliable. Delivers data in same order sent. Error checking. High overhead. |
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UDP |
Transport layer protocol. Best effort. No error checking. Faster than TCP. |
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TCP vs UDP |
The former has much higher overhead but it is more reliable. The latter is best effort and faster. |
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Client-Server applications |
Servers run 24/7. Clients connect to servers, send requests, server responds. An example of relationship is Web servers and web browsers (clients) |
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Peer-to-Peer applications |
All network processes play the same role, but one has to take the role of the "Server" initially to get connected. |
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Sockets and socket programming |
Sockets are used to connect one computer to another.
Socket sock = new Socket(String ip, int port)
Input and output streams can be placed on sockets. |
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active and passive sockets |
Passive sockets are waiting for a connection request. Active sockets are connected. |
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binding sockets to end point addresses |
When a client requests a connection, that socket is bound to client and server by their addresses. |
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Creating TCP servers and clients |
Lame echo |
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Multi-threaded servers |
As soon as connection is received it's passed to its own thread. The server continues to wait for other connection requests. |
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Binary vs text based protocols |
calculator example
Text based require parsing and conversions
Text based are human readable and easily debugged |
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HTTP, IMAP, POP3, DNS, DHCP |
Hypertext transfer Prot. 80 Internet Message Access Prot. Post Office Prot. 110 Domain Name Server Dynamic Host Config Prot. |
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Telnet |
Useful in debugging severs. Can connect to sockets and send text based commands. |