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courses:ct30a5000:assignment3notes [2011/11/07 16:03]
julaakko
courses:ct30a5000:assignment3notes [2012/07/03 12:51]
julaakko
Line 7: Line 7:
 If the answer did provide at least 80% of the presented features one point was given, if the answer covered 50 - 80% of the features ½ point was given. If the answer did provide at least 80% of the presented features one point was given, if the answer covered 50 - 80% of the features ½ point was given.
  
-  - What are the major differences when comparing SCTP to UDP? How about TCP? +  -
-    * **UDP** +
-      * SCTP provides reliable transmission and flow control  +
-      * SCTP has a connection establishment (4-way handshake) +
-      * With UDP the address and port need to be forwarded to lower layers for each packet to be sent, SCTP uses this only for connection establishment +
-      * As UDP is packet oriented it has not got any streams, whereas SCTP supports multiple streams between connected devices +
-    * **TCP** +
-      * SCTP provides multiple streams to use whereas in TCP one stream is available per direction +
-      * SCTP is message oriented (preserves message boundaries) and TCP is stream oriented +
-      * SCTP provides multihoming with the association between connected devices, TCP is more point-to-point with strict connection tied to address and port +
-      * The handshakes are different; STCP has 4-way which uses cookies, whereas TCP has 3-way handshake +
-      * SCTP has no support for half-open connections as in TCP +
-  - Explain 3 benefits that SCTP offers when compared to existing transport layer protocols. +
-    * Multihoming +
-    * 4-way handshake +
-    * Multi streaming +
-    * Message framing +
-    * Graceful shutdown +
-    * Configurable data receiving (unordered data is possible) +
-  - What are the differences between SCTP one-to-one and one-to-many styles? Why there are 2 “different” styles? +
-    * Differences:​ +
-      * One-to-one is strict between connected devices as TCP connection.  +
-      * One socket is peeled of from the listening socket (as with ''​accept()''​ in TCP) for each new connection using one-to-one.  +
-      * The closing of the peeled sockets are done in different way as in one-to-many. +
-      * One-to-many provides full benefits of SCTP: multihoming,​ graceful shutdown, piggybacking of data in handshake messages, automatic initiation of handshake with first send and association events from SCTP kernel. +
-    * The purpose of the one-to-one style is to provide backwards compatibility for existing applications using TCP. However, with one-to-one style packet boundaries are preserved. +
-  - Explain the difference between a connection (TCP) and an association (SCTP). +
-    * Connection is strict between address + port pairs +
-    * Connection is between two addresses of peers, with association multiple addresses on peers can be utilized +
-    * Different handshakes (3-way vs. 4-way) +
-    * TCP connection is stream oriented and SCTP is message oriented +
-    * Association makes it possible to use multiple streams +
-  - What benefits does the multihoming feature of SCTP give? Give at least 3 examples. +
-    * Interfaces (and addresses) can be added and removed dynamically +
-    * Multihoming provides that if one path is disconnected other available one can be used +
-    * Multihoming enables more effective roaming +
-    * The fastest/​least congested route can be utilized for communication +
-    * Better error tolerance +
 ===== Use the protocol to its provided full extent ===== ===== Use the protocol to its provided full extent =====