Bugzilla – Bug 2869
code-review: Implementation of TCP BBR in ns-3
Last modified: 2018-06-01 12:24:46 EDT
This is code review request for the implementation of TCP BBR model in ns-3. Following is the link for the discussion on developers mailing list: http://mailman.isi.edu/pipermail/ns-developers/2018-January/014270.html Link to Github Repo: https://github.com/Vivek-anand-jain/ns-3-dev-git/tree/bbr-dev Note: TCP BBR uses CongControl and Delivery rate estimation, which are already being reviewed (Bug Id: 2868).
Update: 1. Designed and added a preliminary test-suite for BBR called tcp-bbr-test.cc. 2. Updated documentation (tcp.rst) for TCP BBR. 3. Addressed review comments given by Tom Sir for BBR code. The code is available here for the review: https://github.com/Vivek-anand-jain/ns-3-dev-git/tree/bbr-dev
I was using this BBR implementation, and spot 2 bugs. In the TcpTxBuffer class, the m_priorDelivered parameter of struct RateSample should be initialized to 0. The original line 44 uint32_t m_priorDelivered; //!< The delivered count of the most recent packet delivered should be changed to uint32_t m_priorDelivered = 0; //!< The delivered count of the most recent packet delivered Sometime the congestion window goes to a very large value, I figure out the problem was from the TcpBbr::ModulateCwndForRecovery() function line 429 tcb->m_cWnd = std::max (tcb->m_cWnd.Get () - rs->m_packetLoss, tcb->m_segmentSize); should change be to tcb->m_cWnd = std::max ((int)tcb->m_cWnd.Get () - (int)rs->m_packetLoss, (int)tcb->m_segmentSize);