Tegu

Tegu is a reservation manager which provides the ability to create and manage:

• quality of service bandwidth reservations between network endpoints
• flow steering reservations
• wide area network stitching
• port mirroring reservations

Tegu uses an underlying agent, also included in this repository, to directly manage the physical components (Open vSwitch or physical switches) as is needed to implement the reservations. The underlying agent scripts are contained in the agent directory and the tegu_agent binary is in the main directory.

Directory Overview

The Tegu source is divided into the following subdirectories/packages:

agent/bandwidth

This directory contains various direct interfaces (shell scripts) to things like OVS, Arista switches, Floodlight (skoogie), etc.

agent/mirror

This directory contains shell scripts used to create and remove mirrors to ports in an OpenStack environment.

doc

The manual pages for the executables rjprt, tegu, tegu_req and a manual page describing the Tegu API.

gizmos

Source files which implement objects, interfaces and the functions that operate directly on them (link, host, switch, pledge, etc.).

main

Entry point functions (tegu, tegu_agent, and rjprt).

managers

Functions that are driven as goroutines and thus implement major components of the application (reservation manager, fq manager, etc.).

support

Regressions tests.

system

Scripts used to start, stop, and manage Tegu in a Linux environment, as well as the tegu_ha Python script.

File Overview

Here is an overview of the purpose of some of the .go files in this repository.

gizmos directory

fence.go - Implements a user limit fence mechanism.
flight_if.go - A floodlight interface providing methods that allow queries to the controller for gathering link and host information.
host.go - Represents a single host in the network graph and in a path.
init.go - Package level initialization.
link.go - Represents a link between switches in the network graph and in a path.
lite.go - Functions that were implemented quickly to support tegu-lite. These probably should be moved to separate files, or likely into tools, but during the hasty implementation of -lite it was easier to keep them bunched here.
mbox.go - Middlebox representation for steering reservations.
obligation.go - Used to manage an obligation of something over time; references many time slices.
path.go - Manages a path that has been created with a given amount of bandwith.
pledge.go - An interface representing a reservation tracked by resmgr. Implemented by the various pledge types in the pledge_* files.
pledge_window.go - Manages a time window for pledges and provides basic is_active, is_expired functions.
queue.go - Manages information needed to set individual queues for a reservation.
spq.go - A very simple object which allows the return of queue information to a caller in a single bundle (presently, just the struct, no functions exist).
switch.go - Represents a switch in the network graph.
time_slice.go - A single range of time for which a given amount of bandwith has been allocated.
tools.go - Some generic tools but not generic enough to put in gopkgs.

managers directory

fq_mgr.go - Flowmod/queue manager.
fq_mgr_steer.go - Steering based FQ-mgr support.
fq_req.go - Fqmgr request structure and related functions.
globals.go - Constants and a few globals shared by *.go in this directory.
This module also contains the initialisation function that sets all globals up.
http_api.go - Provides the HTTP server, and code to serve URL's under /tegu/api.
http_mirror_api.go - The HTTP interface for mirroring.
network.go - Manages the network graph.
net_req.go - Network manager request struct and related functions.
res_mgr.go - Provides the reservation management logic, supplemented by three support modules: res_mgr_bw.go, res_mgr_mirror.go, and res_mgr_steer.go.
osif.go - OpenStack interface manager.
osif_proj.go - Project specific OpenStack interface functions.

Building Tegu

The Tegu source depends on a set of Go packages that were developed along with Tegu, but are general enough to warrant their not being included here. They are all a part of the github.com/att/gopkgs package library. To use them, clone the git project as described below. They will be referenced as needed during the build process (unlike C, there is no need to build a library to link against). You should be able to do go get github.com/att/gopkgs to pull them down.

Go Environment

The GOPATH variable must be set to the top level directory in your source tree. Within that directory there should be src, bin, and pkg directories. Under src there should be a github.com directory which will hold all of your Go related repositories that are checked out of github.

For example:

export GOPATH=$HOME/godev
cd $GOPATH
mkdir github.com
cd github.com

# fork a copy of the tegu and gopkgs first!!!

# replace XXXXX with your user id, then clone your forks 
git clone https://[email protected]/~XXXXXX/tegu.git
git clone https://[email protected]/~XXXXXX/gopkgs.git

cd tegu
git checkout master

Build Tegu by:

go build main/rjprt.go   		# builds the rjprt binary
go build main/tegu.go   		# builds the tegu binary
go build main/tegu_agent.go		# builds the tegu agent binary

What is a Tegu?

A type of lizard (https://en.wikipedia.org/wiki/Tegu).