Empirical Traffic Generator

What is this?

This is a simple client/server application for generating user defined traffic patterns.

The server is simple: It listens for incoming requests on the specified ports, and replies with a flow with the requested size for each request.

The client connects to a list of servers (given in the input configuration file), and generates requests to randomly chosen servers. For each request, it samples from the input request size and fanout distributions (also specified in the configuration file) to determine the request size and how many flows to generate in parallel for the request. The fanout generates synchronized incast-like flows from a random subset of the servers towards the client. The configuration file also allows several customizations including the desired average receive throughput and the number of requests.

Quick Start

• Run make
• Start server

./bin/server -p 5050 >> /dev/null &

• Start client

./bin/client -c exampleConfig1 -l log -s 123

Build

In the main directory, run:

make 

Two binaries, client and server, will be added under ./bin . The build has been tested with g++ 4.6.3 on Ubuntu, but the code has minimal dependencies and should compile on any Linux system. It does need pthread and tr1 libraries.

Command Line Arguments

Server

Example:

./server -p 5050

-p : port on which the server should listen (optional)
default: 5000

-h : print commnad line usage information and exit

Client

Example:

./client -c exampleConfig1 -l log -s 123

-c : config file name (required)
The configuration file specifies the workload characteristics, and must be formatted as described below.

-l : log file name prefix (optional)
The prefix is used for the two output files with flow and request completion times.
default: log

-s : seed value (optional)
The seed is used for various random number generators. It is recommended that different clients use different seeds to avoid synchronization.
default: set seed based on current machine time (not repeatable)

-h : print commnad line usage information and exit

Client Configuration File

The configuration file specifies the list of servers for the client, the request size and request fanout distributions, average load, and the number of requests.

The format is a sequence of key and value(s), one key per line. The permitted keys are:

• server: ip address and port of an active server.

server localhost 5050
server 192.168.0.1 5000

• req_size_dist: request size distribution file path and name.

req_size_dist /home/jsmith/empirical-traffic-gen/DCTCP_CDF

There must be one request size distribution file, present at the given path, which specifies the CDF of the request size distribution. See "DCTCP_CDF" for an example with proper formatting.

• fanout: fanout value and weight. The fanout and weight are both integers.

fanout 1 50
fanout 2 30
fanout 8 20

The fanout values must be no more than the number of available servers. For each request, the client chooses a fanout with a probability proportional to the weight. For example, with the above configuration, half the requests have fanout 1, and 20% have fanout 8.

• load: average RX throughput at the client in Mbps.

load 1000Mbps

There must only be one load in the configuration file. A special case is:

load 0

Here, the client makes requests back-to-back as quickly as possible.

The client generates requests to roughly match the desired average throughput. If the desired load is high or the CPU is busy, the timing between requests may become innacurate and the actual throughput can be lower than desired. The client outputs the actual throughtput upon termination.

• num_reqs: the total number of requests.

num_reqs 1500

Output

A successful run creates two output files: $pre_reqs.out and $pre_flows.out, where $prefix is the string provided via command line. The two files give the size (in bytes) and completion time (in microseconds) for all requests and flows, respectively. If the fanout is always 1, requests and flows (and hence the outputs) are identical.