Internet Edge and WAN Routing with Cumulus Linux

With this article I wanted to focus on something different than the usual spine and leaf topology and talk about datacenter edge routing.

I was using Cisco routers for many years for Internet Edge and WAN connectivity. The problem with using a vendor like Cisco is the price tag you have to pay and there still might a reason for it to spend the money. But nowadays you get leased-lines handed over as normal Ethernet connection and using a dedicated routers maybe not always necessary if you are not getting too crazy with BGP routing or quality of service.

I was experimenting over the last weeks if I could use a Cumulus Linux switch as an Internet Edge and Wide Area Network router with running different VRFs for internet and WAN connectivity. I came up with the following edge network layout you see below:

For this network, I build an Vagrant topology with Cumulus VX to simulate the edge routing and being able to test the connectivity. Below you see a more detailed view of the Vagrant topology:

Everything is running on Cumulus VX even the firewalls because I just wanted to simulate the traffic flow and see if the network communication is functioning. Also having separate WAN switches might be useful because 1Gbit/s switches are cheaper then 40Gbit/s switches and you need additional SFP for 1Gbit/s connections, another point is to separate your layer 2 WAN connectivity from your internal datacenter network.

Here the assigned IP addresses for this lab:

wan-1 VLAN801 PIP: 217.0.1.2/29 VIP: 217.0.1.1/29
wan-2 VLAN801 PIP: 217.0.1.3/29 VIP: 217.0.1.1/29
wan-1 VLAN802 PIP: 10.100.0.1/29 
wan-2 VLAN802 PIP: 10.100.0.2/29
wan-1 VLAN904 PIP: 217.0.0.2/28 VIP: 217.0.0.1/28
wan-2 VLAN904 PIP: 217.0.0.3/28 VIP: 217.0.0.1/28
fw-1 VLAN904 PIP: 217.0.0.14/28
wan-1 VLAN903 PIP: 10.0.255.34/28 VIP: 10.0.255.33/28
wan-2 VLAN903 PIP: 10.0.255.35/28 VIP: 10.0.255.33/28
fw-2 VLAN903 PIP: 10.0.255.46/28
edge-1 VLAN901 PIP: 10.0.255.2/28 VIP: 10.0.255.1/28
edge-2 VLAN901 PIP: 10.0.255.3/28 VIP: 10.0.255.1/28
fw-1 VLAN901 PIP: 10.0.255.14/28
fw-2 VLAN901 PIP: 10.0.255.12/28
edge-1 VLAN902 PIP: 10.0.255.18/28 VIP: 10.0.255.17/28
edge-2 VLAN902 PIP: 10.0.255.19/28 VIP: 10.0.255.17/28
fw-1 VLAN902 PIP: 10.0.255.30/28

You can find the Github repository for the Vagrant topology here: https://github.com/berndonline/cumulus-edge-vagrant

[email protected]:~/cumulus-edge-vagrant$ vagrant status
Current machine states:

fw-2                      running (libvirt)
fw-1                      running (libvirt)
mgmt-1                    running (libvirt)
edge-2                    running (libvirt)
edge-1                    running (libvirt)
wan-1                     running (libvirt)
wan-2                     running (libvirt)

This environment represents multiple VMs. The VMs are all listed
above with their current state. For more information about a specific
VM, run `vagrant status NAME`.
[email protected]:~/cumulus-edge-vagrant$

I wrote as well an Ansible Playbook to deploy the initial configuration which you can find here: https://github.com/berndonline/cumulus-edge-provision

Let’s execute the playbook:

[email protected]:~/cumulus-edge-vagrant$ ansible-playbook ../cumulus-edge-provision/site.yml

PLAY [edge] ********************************************************************************************************************************************************

TASK [switchgroups : create switch groups based on clag_pairs] *****************************************************************************************************
skipping: [edge-2] => (item=(u'wan', [u'wan-1', u'wan-2']))
skipping: [edge-1] => (item=(u'wan', [u'wan-1', u'wan-2']))
ok: [edge-2] => (item=(u'edge', [u'edge-1', u'edge-2']))
ok: [wan-1] => (item=(u'wan', [u'wan-1', u'wan-2']))
skipping: [wan-1] => (item=(u'edge', [u'edge-1', u'edge-2']))
ok: [edge-1] => (item=(u'edge', [u'edge-1', u'edge-2']))
ok: [wan-2] => (item=(u'wan', [u'wan-1', u'wan-2']))
skipping: [wan-2] => (item=(u'edge', [u'edge-1', u'edge-2']))

TASK [switchgroups : include switch group variables] ***************************************************************************************************************
skipping: [edge-2] => (item=(u'wan', [u'wan-1', u'wan-2']))
skipping: [edge-1] => (item=(u'wan', [u'wan-1', u'wan-2']))
ok: [wan-1] => (item=(u'wan', [u'wan-1', u'wan-2']))
skipping: [wan-1] => (item=(u'edge', [u'edge-1', u'edge-2']))
ok: [wan-2] => (item=(u'wan', [u'wan-1', u'wan-2']))
skipping: [wan-2] => (item=(u'edge', [u'edge-1', u'edge-2']))
ok: [edge-2] => (item=(u'edge', [u'edge-1', u'edge-2']))
ok: [edge-1] => (item=(u'edge', [u'edge-1', u'edge-2']))

...

RUNNING HANDLER [interfaces : reload networking] *******************************************************************************************************************
changed: [edge-2] => (item=ifreload -a)
changed: [edge-1] => (item=ifreload -a)
changed: [wan-1] => (item=ifreload -a)
changed: [wan-2] => (item=ifreload -a)
changed: [edge-2] => (item=sleep 10)
changed: [edge-1] => (item=sleep 10)
changed: [wan-2] => (item=sleep 10)
changed: [wan-1] => (item=sleep 10)

RUNNING HANDLER [routing : reload frr] *****************************************************************************************************************************
changed: [edge-2]
changed: [wan-1]
changed: [wan-2]
changed: [edge-1]

RUNNING HANDLER [ptm : restart ptmd] *******************************************************************************************************************************
changed: [edge-2]
changed: [edge-1]
changed: [wan-2]
changed: [wan-1]

RUNNING HANDLER [ntp : restart ntp] ********************************************************************************************************************************
changed: [wan-1]
changed: [edge-1]
changed: [wan-2]
changed: [edge-2]

RUNNING HANDLER [ifplugd : restart ifplugd] ************************************************************************************************************************
changed: [edge-1]
changed: [wan-1]
changed: [edge-2]
changed: [wan-2]

PLAY RECAP *********************************************************************************************************************************************************
edge-1                     : ok=21   changed=17   unreachable=0    failed=0
edge-2                     : ok=21   changed=17   unreachable=0    failed=0
wan-1                      : ok=21   changed=17   unreachable=0    failed=0
wan-2                      : ok=21   changed=17   unreachable=0    failed=0

[email protected]:~/cumulus-edge-vagrant$

At last but not least I wrote a simple Ansible Playbook for connectivity testing using ping what you can find here: https://github.com/berndonline/cumulus-edge-provision/blob/master/icmp_check.yml

[email protected]:~/cumulus-edge-vagrant$ ansible-playbook ../cumulus-edge-provision/check_icmp.yml

PLAY [exit edge] *********************************************************************************************************************************************************************************************************************

TASK [connectivity check from frontend firewall] *************************************************************************************************************************************************************************************
skipping: [fw-2] => (item=10.0.255.33)
skipping: [fw-2] => (item=10.0.255.17)
skipping: [fw-2] => (item=10.0.255.1)
skipping: [fw-2] => (item=217.0.0.1)
skipping: [edge-2] => (item=10.0.255.33)
skipping: [edge-2] => (item=10.0.255.17)
skipping: [edge-2] => (item=10.0.255.1)
skipping: [edge-1] => (item=10.0.255.33)
skipping: [edge-2] => (item=217.0.0.1)
skipping: [edge-1] => (item=10.0.255.17)
skipping: [edge-1] => (item=10.0.255.1)
skipping: [wan-1] => (item=10.0.255.33)
skipping: [edge-1] => (item=217.0.0.1)
skipping: [wan-1] => (item=10.0.255.17)
skipping: [wan-1] => (item=10.0.255.1)
skipping: [wan-1] => (item=217.0.0.1)
skipping: [wan-2] => (item=10.0.255.33)
skipping: [wan-2] => (item=10.0.255.17)
skipping: [wan-2] => (item=10.0.255.1)
skipping: [wan-2] => (item=217.0.0.1)
changed: [fw-1] => (item=10.0.255.33)
changed: [fw-1] => (item=10.0.255.17)
changed: [fw-1] => (item=10.0.255.1)
changed: [fw-1] => (item=217.0.0.1)
...
PLAY RECAP ***************************************************************************************************************************************************************************************************************************
edge-1                     : ok=2    changed=2    unreachable=0    failed=0
edge-2                     : ok=2    changed=2    unreachable=0    failed=0
fw-1                       : ok=1    changed=1    unreachable=0    failed=0
fw-2                       : ok=1    changed=1    unreachable=0    failed=0
wan-1                      : ok=2    changed=2    unreachable=0    failed=0
wan-2                      : ok=2    changed=2    unreachable=0    failed=0

[email protected]:~/cumulus-edge-vagrant$

The icmp check shows that in general the edge routing is working but I need to do some further testing with this if this can be used in a production environment.

If using switch hardware is not the right fit you can still install and use Free Range Routing (FRR) from Cumulus Networks on other Linux distributions and pick server hardware for your own custom edge router. I would only recommend checking Linux kernel support for VRF when choosing another Linux OS. Also have a look at my article about Open Source Routing GRE over IPSec with StrongSwan and Cisco IOS-XE where I build a Debian software router.

Please share your feedback and leave a comment.

Continuous Integration and Delivery for Networking with Cumulus Linux

Continuous Integration – Continuous Delivery (CICD) is becoming more and more popular for network automation but the problem is how to validate your scripts and stage the configuration because you don’t want to deploy untested code to a production system. Especially in networking that could be pretty destructive if you made a mistake which could cause a loss in connectivity.

I spend some days working on a Cumulus Linux lab using Vagrant which I use to stage configuration. You find the basic Ansible playbook and the gitlab-ci configuration for the Cumulus lab in my Github repo: cumulus-lab-provision

For the continuous integration and delivery (CI/CD) pipeline I am using Gitlab.com and their Gitlab-runner which is running on my server. I will not get into too much detail what is needed on the server, basically it runs vargant, libvirt (kvm), virtualbox, ansible and the gitlab-runner.

  • You need to register your Gitlab-runner with the Gitlab repository.

  • The next step is to create your .gitlab-ci.yml which defines your CI-pipeline.
---
stages:
    - validate ansible
    - staging
    - production
validate:
    stage: validate ansible
    script:
        - bash ./linter.sh
staging:
    before_script:
        - git clone https://github.com/berndonline/cumulus-lab-vagrant.git
        - cd cumulus-lab-vagrant/
        - python ./topology_converter.py ./topology-staging.dot
          -p libvirt --ansible-hostfile
    stage: staging
    script:
        - bash ../staging.sh
production:
    before_script:
        - git clone https://github.com/berndonline/cumulus-lab-vagrant.git
        - cd cumulus-lab-vagrant/
        - python ./topology_converter.py ./topology-production.dot
          -p libvirt --ansible-hostfile
    stage: production
    when: manual
    script:
        - bash ../production.sh
    only:
        - master

In the gitlab-ci you see that I clone the cumulus vagrant lab which I use to spin-up a virtual staging environment and run the Ansible playbook against the virtual lab. The production stage is in my example also a vagrant environment because I had no physical switches for testing.

  • Basically any commit or merge in the Gitlab repo triggers the pipeline which I define in the gitlab-ci.

  • You can see the details in the running job. The first stage is only to validate that the YAML files have the correct syntax.

  • Here the details of the running job of staging and when everything goes well the job succeeded.

  • The last stage is production which needs to be triggered manually.

  • After the changes run through all defined stages you see that you successfully validate, staged and deployed your configuration to a cumulus production system.

This is a complete different way of working for a network engineer but the way it goes in fully automated datacenter network environments. It gets very powerful when you combine this with the Cumulus NetQ server to validate the state of your switch fabric after you run changes in production.

The next topic I am working on, is using Cumulus NetQ to validate configuration changes.

Here again my two repositories I use:

https://github.com/berndonline/cumulus-lab-vagrant

https://github.com/berndonline/cumulus-lab-provision

Read my new posts about an Ansible Playbook for Cumulus Linux BGP IP-Fabric and Cumulus NetQ Validation and BGP EVPN and VXLAN with Cumulus Linux.

Cumulus Linux network simulation using Vagrant

I was using GNS3 for quite some time but it was not very flexible if you quickly wanted to test something and even more complicated if you used a different computer or shared your projects.

I spend some time with Vagrant to build a virtual Cumulus Linux lab environment which can run basically on every computer. Simulating network environments is the future when you want to test and validate your automation scripts.

My lab diagram:

I created different topology.dot files and used the Cumulus topology converter on Github to create my lab with Virtualbox or Libvirt (KVM). I did some modification to the initialise scripts for the switches and the management server. Everything you find in my Github repo https://github.com/berndonline/cumulus-lab-vagrant.

The topology file basically defines your network and the converter creates the Vagrantfile.

In the management topology file you have all servers (incl. management) like in the network diagram above. The Cumulus switches you can only access via the management server.

Very similar to the topology-mgmt.dot but in this one the management server is running Cumulus NetQ which you need to first import into your Vagrant. Here the link to the Cumulus NetQ demo on Github.

In this topology file you find a basic staging lab without servers where you can access the Cumulus switches directly via their Vagrant IP. I mainly use this to quickly test something like updating Cumulus switches or validating Ansible playbooks.

In this topology file you find a basic production lab where you can access the Cumulus switches directly via their Vagrant IP and have Cumulus NetQ as management server.

Basically to convert a topology into a Vagrantfile you just need to run the following command:

python topology_converter.py topology-staging.dot -p libvirt --ansible-hostfile

I use KVM in my example and want that Vagrant creates an Ansible inventory file and run playbooks directly agains the switches.

Check the status of the vagrant environment:

[email protected]:~/cumulus-lab-vagrant$ vagrant status
Current machine states:

spine-1                   not created (libvirt)
spine-2                   not created (libvirt)
leaf-1                    not created (libvirt)
leaf-3                    not created (libvirt)
leaf-2                    not created (libvirt)
leaf-4                    not created (libvirt)
mgmt-1                    not created (libvirt)
edge-2                    not created (libvirt)
edge-1                    not created (libvirt)

This environment represents multiple VMs. The VMs are all listed
above with their current state. For more information about a specific
VM, run `vagrant status NAME`.
[email protected]:~/cumulus-lab-vagrant$

To start the devices run:

vagrant up

If you use the topology files with management server you need to start first the management server and then the management switch before you boot the rest of the switches:

vagrant up mgmt-server
vagrant up mgmt-1
vagrant up

The switches will pull some part of their configuration from the management server.

Output if you start the environment:

[email protected]:~/cumulus-lab-vagrant$ vagrant up spine-1
Bringing machine 'spine-1' up with 'libvirt' provider...
==> spine-1: Creating image (snapshot of base box volume).
==> spine-1: Creating domain with the following settings...
==> spine-1:  -- Name:              cumulus-lab-vagrant_spine-1
==> spine-1:  -- Domain type:       kvm
==> spine-1:  -- Cpus:              1
==> spine-1:  -- Feature:           acpi
==> spine-1:  -- Feature:           apic
==> spine-1:  -- Feature:           pae
==> spine-1:  -- Memory:            512M
==> spine-1:  -- Management MAC:
==> spine-1:  -- Loader:
==> spine-1:  -- Base box:          CumulusCommunity/cumulus-vx
==> spine-1:  -- Storage pool:      default
==> spine-1:  -- Image:             /var/lib/libvirt/images/cumulus-lab-vagrant_spine-1.img (4G)
==> spine-1:  -- Volume Cache:      default
==> spine-1:  -- Kernel:
==> spine-1:  -- Initrd:
==> spine-1:  -- Graphics Type:     vnc
==> spine-1:  -- Graphics Port:     5900
==> spine-1:  -- Graphics IP:       127.0.0.1
==> spine-1:  -- Graphics Password: Not defined
==> spine-1:  -- Video Type:        cirrus
==> spine-1:  -- Video VRAM:        9216
==> spine-1:  -- Sound Type:
==> spine-1:  -- Keymap:            en-us
==> spine-1:  -- TPM Path:
==> spine-1:  -- INPUT:             type=mouse, bus=ps2
==> spine-1: Creating shared folders metadata...
==> spine-1: Starting domain.
==> spine-1: Waiting for domain to get an IP address...
==> spine-1: Waiting for SSH to become available...
    spine-1:
    spine-1: Vagrant insecure key detected. Vagrant will automatically replace
    spine-1: this with a newly generated keypair for better security.
    spine-1:
    spine-1: Inserting generated public key within guest...
    spine-1: Removing insecure key from the guest if it's present...
    spine-1: Key inserted! Disconnecting and reconnecting using new SSH key...
==> spine-1: Setting hostname...
==> spine-1: Configuring and enabling network interfaces...
....
==> spine-1: #################################
==> spine-1:   Running Switch Post Config (config_vagrant_switch.sh)
==> spine-1: #################################
==> spine-1:  ###Creating SSH keys for cumulus user ###
==> spine-1: #################################
==> spine-1:    Finished
==> spine-1: #################################
==> spine-1: Running provisioner: shell...
    spine-1: Running: inline script
==> spine-1: Running provisioner: shell...
    spine-1: Running: inline script
==> spine-1:   INFO: Adding UDEV Rule: a0:00:00:00:00:21 --> eth0
==> spine-1: Running provisioner: shell...
    spine-1: Running: inline script
==> spine-1:   INFO: Adding UDEV Rule: 44:38:39:00:00:30 --> swp1
==> spine-1: Running provisioner: shell...
    spine-1: Running: inline script
==> spine-1:   INFO: Adding UDEV Rule: 44:38:39:00:00:04 --> swp2
==> spine-1: Running provisioner: shell...
    spine-1: Running: inline script
==> spine-1:   INFO: Adding UDEV Rule: 44:38:39:00:00:26 --> swp3
==> spine-1: Running provisioner: shell...
    spine-1: Running: inline script
==> spine-1:   INFO: Adding UDEV Rule: 44:38:39:00:00:0a --> swp4
==> spine-1: Running provisioner: shell...
    spine-1: Running: inline script
==> spine-1:   INFO: Adding UDEV Rule: 44:38:39:00:00:22 --> swp51
==> spine-1: Running provisioner: shell...
    spine-1: Running: inline script
==> spine-1:   INFO: Adding UDEV Rule: 44:38:39:00:00:0d --> swp52
==> spine-1: Running provisioner: shell...
    spine-1: Running: inline script
==> spine-1:   INFO: Adding UDEV Rule: 44:38:39:00:00:10 --> swp53
==> spine-1: Running provisioner: shell...
    spine-1: Running: inline script
==> spine-1:   INFO: Adding UDEV Rule: 44:38:39:00:00:23 --> swp54
==> spine-1: Running provisioner: shell...
    spine-1: Running: inline script
==> spine-1:   INFO: Adding UDEV Rule: Vagrant interface = eth1
==> spine-1: #### UDEV Rules (/etc/udev/rules.d/70-persistent-net.rules) ####
==> spine-1: ACTION=="add", SUBSYSTEM=="net", ATTR{address}=="a0:00:00:00:00:21", NAME="eth0", SUBSYSTEMS=="pci"
==> spine-1: ACTION=="add", SUBSYSTEM=="net", ATTR{address}=="44:38:39:00:00:30", NAME="swp1", SUBSYSTEMS=="pci"
==> spine-1: ACTION=="add", SUBSYSTEM=="net", ATTR{address}=="44:38:39:00:00:04", NAME="swp2", SUBSYSTEMS=="pci"
==> spine-1: ACTION=="add", SUBSYSTEM=="net", ATTR{address}=="44:38:39:00:00:26", NAME="swp3", SUBSYSTEMS=="pci"
==> spine-1: ACTION=="add", SUBSYSTEM=="net", ATTR{address}=="44:38:39:00:00:0a", NAME="swp4", SUBSYSTEMS=="pci"
==> spine-1: ACTION=="add", SUBSYSTEM=="net", ATTR{address}=="44:38:39:00:00:22", NAME="swp51", SUBSYSTEMS=="pci"
==> spine-1: ACTION=="add", SUBSYSTEM=="net", ATTR{address}=="44:38:39:00:00:0d", NAME="swp52", SUBSYSTEMS=="pci"
==> spine-1: ACTION=="add", SUBSYSTEM=="net", ATTR{address}=="44:38:39:00:00:10", NAME="swp53", SUBSYSTEMS=="pci"
==> spine-1: ACTION=="add", SUBSYSTEM=="net", ATTR{address}=="44:38:39:00:00:23", NAME="swp54", SUBSYSTEMS=="pci"
==> spine-1: ACTION=="add", SUBSYSTEM=="net", ATTR{ifindex}=="2", NAME="eth1", SUBSYSTEMS=="pci"
==> spine-1: Running provisioner: shell...
    spine-1: Running: inline script
==> spine-1: ### RUNNING CUMULUS EXTRA CONFIG ###
==> spine-1:   INFO: Detected a 3.x Based Release
==> spine-1: ### Disabling default remap on Cumulus VX...
==> spine-1: ### Disabling ZTP service...
==> spine-1: Removed symlink /etc/systemd/system/multi-user.target.wants/ztp.service.
==> spine-1: ### Resetting ZTP to work next boot...
==> spine-1: Created symlink from /etc/systemd/system/multi-user.target.wants/ztp.service to /lib/systemd/system/ztp.service.
==> spine-1:   INFO: Detected Cumulus Linux v3.3.2 Release
==> spine-1: ### Fixing ONIE DHCP to avoid Vagrant Interface ###
==> spine-1:      Note: Installing from ONIE will undo these changes.
==> spine-1: ### Giving Vagrant User Ability to Run NCLU Commands ###
==> spine-1: ### DONE ###
==> spine-1: ### Rebooting Device to Apply Remap...

At the end you are able to connect to the Cumulus switch:

[email protected]:~/cumulus-lab-vagrant$ vagrant ssh spine-1

Welcome to Cumulus VX (TM)

Cumulus VX (TM) is a community supported virtual appliance designed for
experiencing, testing and prototyping Cumulus Networks' latest technology.
For any questions or technical support, visit our community site at:
http://community.cumulusnetworks.com

The registered trademark Linux (R) is used pursuant to a sublicense from LMI,
the exclusive licensee of Linus Torvalds, owner of the mark on a world-wide
basis.
[email protected]:~$

To destroy the Vagrant environment:

[email protected]:~/cumulus-lab-vagrant$ vagrant destroy spine-1
==> spine-2: Remove stale volume...
==> spine-2: Domain is not created. Please run `vagrant up` first.
==> spine-1: Removing domain...

My goal is to adopt some NetDevOps practice and use this in networking = NetOps, currently working on an Continuous Integration and Delivery (CI/CD) pipeline for Cumulus Linux network environments. The Vagrant lab was one of the prerequisites to simulate the changes before deploying this to production but more will follow in my next blog post.

Read my new post about an Ansible Playbook for Cumulus Linux BGP IP-Fabric and Cumulus NetQ Validation.