New TCP Socket Architecture
In the following, a new architecture for TCP socket implementation is proposed. This is to replace the old TcpSocketImpl class in NS-3.8 so that different favors of TCP can be easily implemented.
Old Structure
As of change set 6273:8d70de29d514 in the Mercurial, TCP simulation is implemented by class TcpSocketImpl, in src/internet-stack/tcp-socket-impl.h and src/internet-stack/tcp-socket-impl.cc. The TcpSocketImpl class is implementing TCP NewReno, despite the Doxygen comment claims that is implementing Tahoe.
The TcpSocketImpl class is derived from TcpSocket class, which in turn, is derived from Socket class. The TcpSocket class is merely an empty class defining the interface for attribute get/set. Examples of the attributes configured by the interface of TcpSocket class are the send and receive buffer sizes, initial congestion window size, etc. The Socket class, however, provides the interface for the L7 application to call.
New Structure
The new structure, TcpSocketBase class, is having the same relationship to TcpSocket and Socket classes as TcpSocketImpl. However, instead of providing a concrete TCP implementation, it is designed to meet the following goals:
- Provide only the function common to all TCP classes, namely, the implementation of TCP state machine
- Minimize the code footprint and make it modular to make it easier to understand
To be continued
