of_stats: A Python repository from gleybersonandrade

Overview

In order to manage a network, an administrator must have updated and reliable statistics about it, in several levels of deepness, from a switch port inbound and outbound traffic to the traffic of different connected networks.

To achieve that, this Network Application collects statistical data provided by the switches connected to the controller. We do not use SNMP protocol because the OpenFlow protocol already provide this data. The data is stored to be provided later through a REST API. This API can supply instant data, historical data, and also some calculated information.

The provided statistics, per switch, are:

Ports/Interfaces: bytes/sec, utilization, dropped packets/sec and errors/sec split into transmission and reception; interface name, MAC address and link speed (Bps);
Flows: packets/sec, bytes/sec;

Installing

RRDTool

Note

We currently use rrd to keep persistence in data, but future versions of this napp will allow you to choose what kind of backend you want to use.

Linux packages

Currently, this NApp uses rrdtool and its Python wrapper needs several packages to be installed and run. In Ubuntu, you can install them by:

apt install rrdtool python3.6-dev librrd-dev

Python packages

With the Linux packages above installed, just run:

pip install rrdtool

NApp installation

All of the Kytos Network Applications are located in the online NApps repository. To install this NApp, run:

kytos napps install kytos/of_stats

kytos napps install kytos/topology

Developers

To run the NApp from the source code, install the requirements and run:

git clone https://github.com/kytos/of_stats.git
cd of_stats
kytos napps install kytos/of_stats

With the setup above, git pull will update NApp.

Configuring

There's no need to configure anything for this NApp to run. Read the sections below if you need to change of_stats behavior or just want to know more details on how it works.

Settings file

You can customize settings like how long to wait before asking the switches for more statistics, as well as rrdtool-related configuration in the file settings.py.

Custom bandwidth

Sometimes, the link speed is wrongly reported by the switch or there's no such speed in the protocol specification. In these cases, you can manually define the speeds in the file user_speed.json. Changes to this file will be loaded automatically without the need to restart the controller.

Setting interface speeds manually is quite easy. Just create user_speed.json by copying and customizing the provided user_speed.example.json file. Let's see what the provided example means:

{
  "default": 12500000000,
  "00:00:00:00:00:00:00:01":
  {
    "default": 1250000000,
    "4": 125000000
  }
}

Keep in mind that, for consistency reasons, we try to keep the units in bytes whenever possible. Thus, speeds should specified in bytes/sec (not necessarily integers).

Any value in this file overrides the OpenFlow values returned by the switches. In this file, inner values take precedence over outer ones.

The default values are optional. The first line has a default value that specifies the speed of any interface that is not found in this file (12,500,000,000 Bps = 100 Gbps). Then, there's a default value set for all interfaces of the switch whose dpid is 00:...:00:01 (1,250,000,000 Bps = 10 Gbps). Even more specifically, its interface with port number 4 is 125,000,000 Bps (1 Gbps).

To make it even more clear, find below the speed of several interfaces when user_speed.json has the content above:

DPID 1	Port	Speed (Gbps)
00:00:00:00:00:00:00:01	4	1
00:00:00:00:00:00:00:01	2	10
00:00:00:00:00:00:00:02	4	100
00:00:00:00:00:00:00:02	2	100

Events

Listened

kytos/of_core.v0x01.messages.in.ofpt_stats_reply

This event contains the statistics to be processed.

Content

A KytosEvent object containing:

message: a StatsReply object;
source: contains the switch datapath ID in source.switch.dpid.

Rest API

You can find a list of the available endpoints and example input/output in the 'REST API' tab in this NApp's webpage in the Kytos NApps Server.

Troubleshooting

Attention!

The filenames below are relative to this NApp's folder. If you run Kytos as root, it is /var/lib/kytos/napps/kytos/of_stats or, if using virtualenv, $VIRTUAL_ENV/var/lib/kytos/napps/kytos/of_stats.

Wrong link utilization

Check whether the link bandwidth is correct. If it is not, set the correct bandwidth by following the instructions in Configuring, Custom bandwidth.

New settings are not applied

Some changes in settings.py require recreating the database. Check the section Deleting the database below.

Unexpected results

If you get fewer points than expected for a specific flow or port, it might be that there's not enough data to calculate all of them. Try to specify the "start" parameter using a later time that you know traffic was being collected.

You may also try to delete RRD databases (see below) so they can be recreated with the latest configuration.

Deleting the database

You don't have to stop the controller to delete the databases. This NApp will recreate them as needed after you run (no need to restart the NApp):

rm -rf rrd/flows rrd/ports

gleybersonandrade/of_stats