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.

Cumulus Networks (Open Networking)

In my recent data centre network redesign project I used Cumulus Linux on Open Networking switches from Dell (S3048-ON and S4048-ON). I heard from Cumulus Networks around 2 1/2 years ago and did some testing with the VX appliance back then but I was waiting for the official release of the VRF feature. Ones I got the go ahead for the data centre redesign project, it was clear to replace Cisco and use Cumulus Linux on the all the data centre switches.

I was one of the first Cumulus users of finding a bug with VRF in Quagga because of extensive use of VRFs:

RN-518 (CM-13328) - Quagga sometimes installs a duplicate static route

After a Cumulus Linux switch with VRF routes installed was 
rebooted, the VRF routes were present in the kernel but 
not installed into hardware. Restarting Quagga resolved 
the issue.

This issue has been fixed in the update 
to the 3.1.2 repository.

Like in my latest post the idea was to use a converged network stack which needed some more advanced configuration on the switch itself with different VRFs to split the data centre into Corporate (office) and Production.

So far I have a very good experience with Cumulus Networks, the support is awesome and very skilled!

Data centre network redesign

Over the last month I was busy working on an data centre redesign for my company which I finished this weekend in one of the three data centre’s.

The old network design was very outdated and bad choice of network equipment; Cisco Catalyst 6500 core switch for a small data centre environment with 8 racks is total overkill, two firewall clusters Juniper ISG2000 and Cisco ASA 5550 which were badly integrated and the configuration was a mess.

For the new network I followed a more converged idea to use a small and compact network to be as flexible as possible but also downsize the overall footprint and remove complexity. We adopted parts of DevOps “I like to call it NetOps” and used Ansible to automate the configuration deployment, the whole network stack is deployed within 90 seconds.

Used equipment:

  1. Top two switches were Dell S3048-ON running Cumulus Networks OS and used for internet- and leased-lines
  2. Under the two Dell WAN switches are two Cisco ASR 1001-X router for internet and wide area network (OSPF) routing.
  3. Under the Cisco router, two Dell S4048-ON core switches running Cumulus Network OS and connected existing HP Blade Center’s and HP DL servers. The new Tintri storage for the VMware vSphere clusters was also connected directly to the core switches.
  4. Under the Dell core switches are two Cisco ASA 5545-X in multi-context mode running Production, Corporate and S2S VPN firewalls.
  5. On the bottom of the network stack were existing serial console server and Cisco Catalyst switch for management network.

Now I will start with the deployment of VMware NSX SDN (Software defined Network) in this data centre. Ones VMware NSX is finished and handed over to the Systems Engineers I will do the same exercise for the 2nd data centre in the UK.

About Cumulus Linux and VMware NSX SDN I will publish some more information and my experience in the coming month.

How correct network cabling should look like!

Network cabling in a data centre should not look like in the following picture 😉 there you have no structure and makes it difficult for someone else to look through how every server is connected.

To make your life and work easier you just need to think before about what colors you use and then create an cabling standard what you always follow. Basically I choose three colors: blue, red and yellow. Yellow is management traffic, blue and red are main network connections (ports on the server must be teamed to have a redundant connectivity).

Here you clearly see that every server has an redundant connection to one of the switches in the rack. The blue cables are always connected to the top switch in the rack and the red to the second switch.

Here how the complete rack looks like, always look to keep it organised and follow your cabling standard.