##1 What is Trinity ? A network virtualization solution for multi-tenant public clouds.

##2 Analysis of source codes

###2.1 Makefile EXTRA_CFLAGS +=-DTRINITY indicates that Trinity is enabled. If you delete this line, the kernel module just works as ElasticSwitch (SIGCOMM 2013).

###2.2 user.c and control.h These two files delivers the implementation of the configureation program in user space. It communicates with kernel module using ioctl.

###2.3 tx.h This file implements the TX (transmit) context. There are 3 important structures in this file: pair_tx_context , endpoint_tx_context and tx_context. The most imporant structure is pair_tx_context which describes the structure of a VM-to-VM pair. If Trinity is enabled, pair_tx_context leverages a special rate limiter: dual_tbf_rl, a dual priority queue based token bucket rate limiter. Otherwise, pair_tx_context just employs normal token bucket rate limiter.

###2.4 tbf.h This file describes the implementation of token bucket rate limiter.

###2.5 dual_tbf.h This file describes the implementation of dual priority queue based token bucket rate limiter. If you just want to use ElasticSwitch, no need to read this file.

###2.6 rl.h The header file for rate limiting (rl). It describes the tasklet and hrtimer callback functions of above two rate limiters.

###2.7 rc.h This file describes a cubic-like rate control (rc) algorithm to increase rate.

###2.8 network.h This file gives the implementation of several network operation functions. generate_feedback shows how to generate feedback packets in kernel to deliver congestion information.

###2.9 rx.h This file implements the RX (receive) context. There are 3 important structures in this file: pair_rx_context , endpoint_rx_context and rx_context.

###2.10 flow.h and hash.h These two files give the implementation of a flow table. If you just want to use ElasticSwitch, no need to read these files.

###2.11 params.h Definitions of imporant global variables.

###2.12 trinity.c main program