Troubleshoot Openstack Networking with Python

As an Openstack Administrator for a while, I found the most complicated topic to be understood in openstack project is Networking and how instances ( formerly virtual machines) are communicated with each other and with external world.

Unlike VMWare ESXI, where you can just create vSwitch and attach a VM to it, Openstack Networking is much more complex that that. You need first to define Network type itself(Flat, VLAN, VxLAN, GRE), attach it to the subnet with IPv4 or IPv6 Block, Create a Floating IP address if this network will be connected externally to a provider network and optionally create an internal router to route between different networks and subnets. lots of steps!


Floating ip and neutron router in nutshellimage

Also Neutron itself doesn’t provide an actual networking to the instances. it just a wrapper to a drivers called “Mechanism Drivers” on which they provide the actual networking(switching, routing and so on). The most famous one is the OpenVswitch which provide basic and advanced switching between instances and external world


But openvswtich lack the capability of enforcing security policy over incoming and outgoing packets, That’s why Openstack community choose to connect the linuxBridge with OpenVswitch to solve this problem which introduce another layer of complexity!

Imagine that you need to attach one ethernet interface to instance. Openstack creates additional Four different interfaces to satisfy the need of OpenVswitch and LinuxBridge. Very complex approach really!. Below is an example of these interfaces. You can find more about it by clicking on image itslef!

So Where’s the problem?

when you face a problem in openstack networking like instance is not pingable from outside world, You can’t reach the instance gateway, You can’t get an IP address from DHCP pool or even you don’t see any incoming or outgoing traffic from it. Chances are you’ve missed something in networking configuration and you need to fix it.

Let’s start by answering the following questions:

1- How many interfaces assigned to an instance

2- What’s  the MAC address of each interface?

3- What’s the IP address of each interface?

4- What’s the internal VLAN assign by OVS to our interface?

5- How will the External Network (Provider Network) treat the traffic from each interface? (Strip VLAN, Add a VLAN, Modify a VLAN..etc)

6-Which ports in integration bridge (br-int) and External Bridge (br-ex) are connecting our instance ? and which flow table rules are applied on them

Answering the above questions will help us , a lot , in troubleshooting any networking problem in openstack.

You can use some useful commands like (ip a , ovs-vsctl show, neutron port-list ..etc) in your troubleshooting. However you will spent a lot of time trying to connecting everything together especially if you’ve environment with hundreds of instances and hundreds of networks.

So let’s Automate this job by using Python!

I wrote a python script that can do this job easily. it utilize two famous python libraries requests and netmiko  to connect to Openstack Keystone API service , grep the required information from it and parse the returned info and finally connecting the dots . it will print a nice report with all detailed information.

So How Does it Work?

First we define the Openstack Credentials (if you’ve multi-node installation then define the keystone ip address)


Then will send API request to Openstack Keystone to generate a Token. Token will be used later to authenticate us against any other openstack service


You can see the Openstack Token workflow in below picture. Don’t forget that Token has an expiration time so you have to use it before that date.

Next we will parse the returned output to find out the MAC address and IP address. I wrote a function on which you give it an instance name and it will do the rest. I thought it would be better to write it like that in case I need to use it later in any of my other projects


Unfortunately, OVS doesn’t provide an API interface like openstack. So I had to use the netmiko  library to send the required commands and parse the output using the linux text stream like cut and grep commands. The returned output require additional handling on which I choose to do from Python itself.


Finally I defined a function that use the above two methods to generate the required report. The returned output is concatenated together and grouped per physical (or should I say Virtual!) network interface


This is where you connect the dot for each part of neutron project either neutron itself or any defined mechanism drivers.



Running this code against one my Openstack environment, I can easily identify how openstack networking handle and forward the traffic from each interface in my instance.

You can answer the above mentioned questions, whether the IP address, MAC , VLAN tagging and OVS bridge handling per Network interface attached to the instance

You can even visualize it Smile


Finally you can Find the code in my GitHub repo here

Wrapping Up

Many people find openstack is complex and hard to understand, I partially agree with them. However it provides a lot of tools and interfaces on which can be used to get the job done and make your life easy. Neutron is a great and modular project under openstack umbrella and you can automate a lot of neutron tasks by using Python. The Sky is your only limit.

I hope this has been informative for your and I’d like to thank you for reading. Feel free to comment or share your experience in troubleshooting problems in openstack


Introduction to SDN and NFV

If you’re confused about what’s the difference between SDN, NFV, Overlays and automation or what’s the role of each technology and how they’re connected

These are introductory slides for explaining the SDN and NFV technologies. what’s the difference between them and when each one is used. Also it talk about some of Cisco products in each area either SDN or NFV or the Automation with some of real use cases deployed in today’s service provider network.

Hope it’s useful and you like it.


NFV ETSI Lab in Egypt

in last few weeks, I’ve been involved on building and designing the NFV lab according to ETSI standard in my company. The ETSI standard is shown in below snapshotimage

The concept of NFV is simple. it tends to convert the functions that exist in your “physical network” to a virtual. functions like DPI, BNG and route reflectors will be converted to Virtual machines.

The left hand side of the picture is called “MANO = Management and Orchestration” where the right hand side of the standard is the real hardware and bunch of hypervisors (KVM, ESXI)


This allow to create many use cases such as service chaining on which subscriber traffic could be easily passed by any type of VNFs (Virtual Network Functions) regardless of it’s physical location. For example the below subscriber traffic is passed by virtual firewall, DDoS and virtual DPI before sending it out to the internet. Other subscriber traffic could be passed by a different “chains”


Cisco has a wide portfolio that cover most of the ETSI components, Let’s explore them in brief


NFV-O : Orchestrator

Cisco has the NSO product (Network Service Orchestrator, before it’s called Tail-F NCS). Tail-F has a huge contribution in defining the YANG language used in service modeling in the NFV. Cisco acquire the Tail-F company two years ago and it’s one of the most successful acquisition in cisco. You can read more about the Tail-F in thislink. The orchestrator job is to orchestrate the service creation over the VNFs and push the correct configuration on them based on many triggers

NSO use a concept of NEDs (Network Element Drivers) that capable of communicate with many many vendors like Sandvine, Palo-alto, Juniper and of course Cisco. it also capable of communicate using the NetConf protocol that allow it to not only orchestrate the VNF but also the PNF (Physical Network Functions – The real hardware and ASICs).

VNF-M: VNF Manager

because your network functions will be a bunch of VMs (Firewall, DPI,..etc). You will need to have a “manager” that manage the CRUD(Creation, Redeploy, Update and Deletion) operation of those VMs. Cisco has a product that called ESC (Elastic Service Controller) that integrate very well with NSO and any type of orchestrator in northbound. In southbound it ‘s capable to communicate with Openstack and VMware through standard RESful services.


The virtual infrastructure manager (openstack or vcenter) are responsible of creating the actual HDD, RAM and CPU for the VNF. Cisco recommend to integrate with RedHat Openstack (RDO)

EMS (or VNF)

This is the network function that become virtual! . I used in this lab the Cisco Cloud Service Router (CSRv) that capable on running most of the ASR functions without a problem (side note: I used it to build a complete SP-WiFi lab for one of the operator here in Egypt and it work very well in EAP-SIM and Portal based scenarios). below is the available VNFs from cisco


My NFV Lab


First I tried  to integrate the Cisco Elastic Service controller with Vmware vCenter but not having much luck on this integration. I stucked in starting the orchestrator service in vCenter process on which I’m thinking it’s one of the component that used by cisco ESC for communicating with VMware infrastructure. also vCenter seems complex solution to me on which limiting my options


Although the ESC is connected to vCenter, and able to read all “tenants” or VMs from it, but it was unable to administrate them



Hmmm, Ok. let’s seal to the other destination, The Openstack Smile

Second I imported the ESC to the openstack and installed it using the python script.


Great. next step is to integrate the ESC with Openstack that took only two minutes! (Thank you VMware for wasting my time!!)

Third, Once Integration is done, You can see that ESC can successfully retrieve all the tenants from the openstack


Also it’s capable of communicating with Openstack services like nova, cinder


And finally it’s capable of reading all compute hosts and hosted instances


Fourth, Push the configuration from orchestrator to ESC and watch Openstack create the images, flavors and attach all networks to CSRv (through the ESC)



Instances page


if you check the ESC portal, you will see immediately the CSR VNF Active, up and running in the ESC


And you can access the CSRv console directly from the ESC through the built-in VNC utility


But really, what’s the job of the ESC?

ESC play a vital role as a VNF manager in monitoring the VNF operations.  for example if one of the VNF that created through the ESC is deleted by mistake. the ESC will detect this event and immediately re-deploy the impacted machine without any intervention from your side. You can program it with many events to be monitored like overloading the VM, underloading, License experience..etc


The ESC communicate with openstack through REST messages over HTTP and order it to create VM (VNF) with specific flavor, Image ID and attached networks) as shown in blow snoop between ESC and Openstack



NFV is one of the hottest topics in service provider area and it soonest they will convert to this model to save much power and space in datacenter and more important is to introduce agility and harmony in today’s complex network. I really recommend you to choose open standard solutions and not limit your options to propriety software. Learn openstack and YANG modeling and be open minded to automation mythology

Finally I’ve the complete NFV lab integrated components (Orchestrator, VNF-Manager, Openstack and VNF) up and running in my company lab. I think it’s the first lab of it’s type here in Egypt to the best of my knowledge Smile

for any questions, please post a comment and we can discuss it together

Thank You


Install Devstack Steps

If you’re new to openstack and you want get some hands on it then you have to install the Devstack. a bundled version for all openstack services and components in one software

The below presentation illustrate how to get the job done in few steps. More to come later to explore the openstack main features and integration with other nodes in SDN/NFV Environment

Vandyke SecureCRT tips and tricks

Whether you are replacing Telnet or Terminal, or need a more capable secure remote access tool, SecureCRT is an application you can live in all day long. With the solid security of SSH, extensive session management, and advanced scripting, SecureCRT will help raise your productivity to the nth degree.


This is a few tips and tricks for people who use the SeccureCRT application for managing the remote servers

Building Python Development Station

my guide to build a python development VM on your local windows machine to combine both the efficiency of linux and the usability of windows laptop – I use pycharm as an example of python IDE but you can use any IDE that support the remote deployment.

For more info about remote deployment function please see the below link



Juniper MX BRAS – Part 3

As you notice from previous configuration. We have to configure the unit 1 with static VLAN (800) to create only ONE SUBSCRIBER INTERFACE . However in real world scenario this not necessarily the case. we need to make MX check the incoming vlan id from DSLAM and handle the creation of both VLANS and Units that hold the PPPoE sessions. BTW, Here’s a golden rule. One Vlan per Unit!



You can find below the interface structure in dynamic configuration. The physical interface is ae(Active Ethernet) and beneath it the auto-configure command that “instantiate” the VLAN and SVLAN from dynamic-profile


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