Mobile Cloud Networking and Mobility Control 131
The extension LS-SCTP is composed of two new elements:
– a new parameter in the INIT and INIT-ACK chunks, which
indicates whether the terminals support the extension;
– two new types of chunks: an LS-Data (Load-Sharing Data)
chunk, used for sending data, and an LS-SACK (Load-Sharing
SACK) acknowledgement chunk, which provides selective
acknowledgements on each path.
Figure 5.22 illustrates the architecture of LS-SCTP. On each side
of the connection, we see an overall “Association Buffer”, a Path
Assignment Module and a Path Monitor. LS-SCTP separates the flow
control from the congestion control. The flow control is managed at
the level of the connection. The terminals use the association buffer to
receive data from all paths before sending them to the corresponding
terminal or to the application.
Figure 5.22. Architecture of LS-SCTP
The fragmentation and reassembling of the data take place in the
connection buffer. Congestion control is performed for each path.
Each path has its own congestion control parameters, such as the size
of the congestion window (cwnd), the slow-start threshold (ssthresh),
the round-trip time (RTT), etc.
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