SR Demo & Controller

A Python Based SR and BGP-LU Route Controller for Traffic Engineering.

An SR Controller that pushes BGP-LU routes for traffic engineering in an MPLS ISIS-SR Domain

To run the demo install EXABGP (version 4.0.0) along with Python 2.7.

This controller can be run on a VM or a BMS, but in addition is all dockerized and can be run in a container (instructions below)

For details on EXABGP refer to this link:

https://github.com/Exa-Networks/exabgp

INSTALLATION:

To build your own version of the controller all you need to do is install Docker clone the git repository:

    git clone git@github.com:russellkelly/SR_Demo_Repo.git

Switch to the clone directory SR_Demo_Repo

    cd SR_Demo_Repo

Then in the cloned (SR_Demo_Repo) directory run:

    make demo

This command runs build: (Builds the image sr-demo) and spawns container srdemo. It will enter you in to the bash shell of the container.

CONFIGURING AND RUNNING THE SR CONTROLLER

Once the git repository has been cloned locally and the images and containers installed as above and you are in the srdemo bash shell proceed with the following steps:

Step 1: Customize the TopologyVariables.yaml File.

Amend the variables in the file below to match your topology :

TopologyVariables.yaml file. (THIS IS THE ONLY FILE THAT NEEDS TO BE AMENDED)

Change the following in TopologyVariables.yaml:

The LERs to match your topology

    LERs:
      ip_address:
          - xxx.xxx.xxx.xxx
          - xxx.xxx.xxx.xxx

The ISIS-DB export router. This is in your domain will need to have eAPI enabled (see documentation). This router will be used for topology (ISIS DB) export.

    ISIS-DB-Poll:
      ip_address: xxx.xxx.xxx.xxx
      user: <string>
      password: <string>

Amend the local and remote AS in this file to match your Topology

(NOTE: The rest of the sections should not need to be changed)

Step 2a Configuration Notes for the ISIS-SR topology

All links in the ISIS configuration on the routers need to be configured as p2p links. In EOS it is configured as

    isis network point-to-point

The ISIS configuration should be as a level-2. In EOS this is configured as:

    is-type level-2

Step 2b: Render the LER BGP configlets for the Arista LERs

This is an additional (optional) step. If you want the configurations for the Arista EOS LERs to be rendered you can run the following command from within the container bash shell.

    root@df20977bb044:~# python RenderAristaLERsConfiguration.py

This will create a file LERs.conf with the BGP configlet for every LER in the TopologyVariables.yaml file.

Step 3: Starting, stopping and Restarting the controller

Now one can run controller:

    root@df20977bb044:~# ./StartController.sh

Now browse to the IP address of the VM or local machine where docker is installed, on port 5001

http://localhost:5001

To stop the controller simply run

    root@df20977bb044:~# ./StopController.sh

Or restart the Controller with the script.

    root@df20977bb044:~# ./RestartController.sh

Step 4: Exiting the Container and cleaning up sr-net

When you type "exit" in the the container bash shell the container will exit.

To start the controller again you need to "clean" the sr-net by running the command

    make clean

To detach the tty without exiting the shell,use the escape sequence:

    Ctrl-p + Ctrl-q

This will leave the container running and you will be able to re-attach by simply running:

    docker attach srdemo

TROUBLESHOOTING THE SR CONTROLLER

The container actually runs exabgp and the controller script in separate screen sessions. You can see these screen sessions by running the command below.

    root@f56a7d56c078:~# screen -ls
    There are screens on:
    	66..f56a7d56c078	(02/20/18 01:41:59)	(Detached)
    	69..f56a7d56c078	(02/20/18 01:41:59)	(Detached)
    2 Sockets in /var/run/screen/S-root.

To attach to a screen session again simply run:

    root@f56a7d56c078:~# screen -r <screen id>

As an example from above:

    root@f56a7d56c078:~# screen -r 66..f56a7d56c078

Once you attach to a screen session you will see the debug output from either:

• The exabgp screen session. This can be used to see the request API pushes from Exa and the BGP peering status
• The sr_demo.py script console.

To detach from the screen, but leaving it running, run the following:

    Ctrl-a + Ctrl-d

SYSTEM RUNTIME FILES

app.py

    Fires up a simple HTTP portal on port 5000 so one can post via the
    EXABGP API.

exabgp.env

    Environmental file for exabgp.  Copied into srbase

Makefile/Dockerfile

    For building the demo containers.

sr_demo.py

      This is the main script that is a multiprocess python program.  One
      process runs a Flask application to render the WebUI for interacting
      with the controller.  Another process continually gets the SID's from
      the domain, and announces/removes routes upon any input from user via
      Web UI, or automatically on any topology change.   File itself is
      extensively commented.

index.html

      This is the html file that builds the webpage.

images

      Holds the diagrams for the original demo.  Can replace these if required.
      Note: best to amend the index.html file if you don't want these included

monitor_interface.py

      Monitor Interfaces Command for Arista Devices.  Used in this demo to
      visulize trafficbeing engineered troughout the domain.

      This script continually monitors interfaces in one,
      or more Arista devices.

      I created this program to allow one or a number of switches to be
      monitored at once, running on-box or off, and monitoring multiple
      specifically defined interfaces or all of them, and the ability to
      define variables like packet count, min packet rate to show etc.  

      See the help below:

      Usage: monitor_interfaces.py [options]

      Options:
        -h, --help        show this help message and exit
        -b                This option enables KBps to be dispalyed.  Default is off.
        --count_packet    This option enables packet count to be dispalyed.  Default
                          is off.
        --safe            This option enables configurations to be backed up before
                          running the program and restored upon exiting (Thus
                          keeping the load-interval commands as previous).  Default
                          is off.
        -u USERNAME       Username. Mandatory option
        -p PASSWORD       Password. Mandatory option
        -l LOAD_INTERVAL  explicit interface load-interval rate. If set then every
                          interesting interface has its load-interval set, and
                          subsequently removed when packet-rate drops below 2pps.
                          Values 5-300.  By default the programs sets the system
                          default load-interval to 5
        -r PPSRATE        min packet rate.  Any interface with a rate above this
                          will report status. Default is 2 pps.
        -a HOSTNAMES      One or more hostnames (or IP addresses) of the switches to
                          poll.  Comma separated.  Mandatory option with multiple
                          arguments
        -i INTERFACES     optional argument with multiple arguments.  Ethernet Ports
                          Only- Format: Ethernet<num>, or Eth<num>, comma separated,
                          or range separated with- e.g. Eth21-45 or
                          Eth1,Eth7,Eth21-45


      As an example if I want to monitor devices lf275,fm213 but only
      interfaces Eth2,4 and range 41-48, I want to show packet count and and KBps count
      I would run the follwoing:


      python monitor_interfaces.py -u admin -p admin -r 10 -a lf275,fm213 --count_packet  -b -i Eth1,Eth2, Eth41-48


      For no KBps count and all interfaces over the rate of 10pps:

      python monitor_interfaces.py -u admin -p admin -r 10 -a lf275,fm213,fm382 --count_packet