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.

Ansible Playbook for Cumulus Linux (Layer 2 Fabric)

Here a basic Ansible Playbook for a Cumulus Linux lab which I use for testing. Similar spine and leaf configuration I used in my recent data centre redesign, the playbook includes one VRF and all SVIs are joined the VRF.

I use the Cumulus VX appliance under GNS3 which you can get for free at Cumulus: https://cumulusnetworks.com/products/cumulus-vx/

The first step is to configure the management interface of the Cumulus switches, edit /etc/network/interfaces and afterwards run “ifreload -a” to appy the config changes:

auto eth0
iface eth0
	address 192.168.100.20x/24
	gateway 192.168.100.2

Hosts file:

[spine]
spine-1 
spine-2
[leaf]
leaf-1 
leaf-2 

Before you start, you should push your ssh keys and set the hostname to prepare the switches.

Now we are ready to deploy the interface configuration for the Layer 2 Fabric, below the interfaces.yml file.

---
- hosts: all
  remote_user: cumulus
  gather_facts: no
  become: yes
  vars:
    ansible_become_pass: "CumulusLinux!"
    spine_interfaces:
      - { clag: bond1, desc: downlink-leaf, clagid: 1, port: swp1 swp2 }
    spine_bridge_ports: "peerlink bond1"
    bridge_vlans: "100-199"
    spine_vrf: "vrf-prod"
    spine_bridge:
      - { desc: web, vlan: 100, address: "{{ vlan100_address }}", address_virtual: "00:00:5e:00:01:00 10.1.0.254/24", vrf: vrf-prod }
      - { desc: app, vlan: 101, address: "{{ vlan101_address }}", address_virtual: "00:00:5e:00:01:01 10.1.1.254/24", vrf: vrf-prod }
      - { desc: db, vlan: 102, address: "{{ vlan102_address }}", address_virtual: "00:00:5e:00:01:02 10.1.2.254/24", vrf: vrf-prod }
    leaf_interfaces:
      - { clag: bond1, desc: uplink-spine, clagid: 1, port: swp1 swp2 }
    leaf_access_interfaces:
      - { desc: web-server, vlan: 100, port: swp3 }
      - { desc: app-server, vlan: 101, port: swp4 }
      - { desc: db-server, vlan: 102, port: swp5 }
    leaf_bridge_ports: "bond1 swp3 swp4 swp5"
  handlers:
    - name: ifreload
      command: ifreload -a
  tasks:
    - name: deploys spine interface configuration
      template: src=templates/spine_interfaces.j2 dest=/etc/network/interfaces
      when: "'spine' in group_names"
      notify: ifreload
    - name: deploys leaf interface configuration
      template: src=templates/leaf_interfaces.j2 dest=/etc/network/interfaces
      when: "'leaf' in group_names"
      notify: ifreload

I use Jinja2 templates for the interfaces configuration.

Here the output from the Ansible Playbook which only takes a few seconds to run:

[[email protected] cumulus]$ ansible-playbook interfaces.yml -i hosts

PLAY [all] *********************************************************************

TASK [deploys spine interface configuration] ***********************************
skipping: [leaf-2]
skipping: [leaf-1]
changed: [spine-2]
changed: [spine-1]

TASK [deploys leaf interface configuration] ************************************
skipping: [spine-1]
skipping: [spine-2]
changed: [leaf-1]
changed: [leaf-2]

RUNNING HANDLER [ifreload] *****************************************************
changed: [leaf-2]
changed: [leaf-1]
changed: [spine-2]
changed: [spine-1]

PLAY RECAP *********************************************************************
leaf-1                     : ok=2    changed=2    unreachable=0    failed=0
leaf-2                     : ok=2    changed=2    unreachable=0    failed=0
spine-1                    : ok=2    changed=2    unreachable=0    failed=0
spine-2                    : ok=2    changed=2    unreachable=0    failed=0

[[email protected] cumulus]$

Lets quickly verify the configuration:

[email protected]:~$ net show int

    Name           Master    Speed      MTU  Mode           Remote Host    Remote Port    Summary
--  -------------  --------  -------  -----  -------------  -------------  -------------  ---------------------------------
UP  lo             None      N/A      65536  Loopback                                     IP: 127.0.0.1/8, ::1/128
UP  eth0           None      1G        1500  Mgmt           cumulus        eth0           IP: 192.168.100.205/24
UP  bond1          bridge    2G        1500  Bond/Trunk                                   Bond Members: swp1(UP), swp2(UP)
UP  bridge         None      N/A       1500  Bridge/L2                                    Untagged Members: bond1, peerlink
UP  bridge-100-v0  vrf-prod  N/A       1500  Interface/L3                                 IP: 10.1.0.254/24
UP  bridge-101-v0  vrf-prod  N/A       1500  Interface/L3                                 IP: 10.1.1.254/24
UP  bridge-102-v0  vrf-prod  N/A       1500  Interface/L3                                 IP: 10.1.2.254/24
UP  bridge.100     vrf-prod  N/A       1500  SVI/L3                                       IP: 10.1.0.252/24
UP  bridge.101     vrf-prod  N/A       1500  SVI/L3                                       IP: 10.1.1.252/24
UP  bridge.102     vrf-prod  N/A       1500  SVI/L3                                       IP: 10.1.2.252/24
UP  peerlink       bridge    1G        1500  Bond/Trunk                                   Bond Members: swp11(UP)
UP  peerlink.4094  None      1G        1500  SubInt/L3                                    IP: 169.254.1.1/30
UP  vrf-prod       None      N/A      65536  NotConfigured

[email protected]:~$

[email protected]:~$ net show lldp

LocalPort    Speed    Mode        RemotePort    RemoteHost    Summary
-----------  -------  ----------  ------------  ------------  ----------------------
eth0         1G       Mgmt        eth0          cumulus       IP: 192.168.100.205/24
                                  ====          eth0          spine-2
                                  ====          eth0          leaf-1
                                  ====          eth0          leaf-2
swp1         1G       BondMember  swp1          leaf-1        Master: bond1(UP)
swp2         1G       BondMember  swp2          leaf-2        Master: bond1(UP)
swp11        1G       BondMember  swp11         spine-2       Master: peerlink(UP)
[email protected]:~$
[email protected]:~$ net show int

    Name           Master    Speed      MTU  Mode        Remote Host    Remote Port    Summary
--  -------------  --------  -------  -----  ----------  -------------  -------------  --------------------------------
UP  lo             None      N/A      65536  Loopback                                  IP: 127.0.0.1/8, ::1/128
UP  eth0           None      1G        1500  Mgmt        cumulus        eth0           IP: 192.168.100.207/24
UP  swp3           bridge    1G        1500  Access/L2                                 Untagged VLAN: 100
UP  swp4           bridge    1G        1500  Access/L2                                 Untagged VLAN: 101
UP  swp5           bridge    1G        1500  Access/L2                                 Untagged VLAN: 102
UP  bond1          bridge    2G        1500  Bond/Trunk                                Bond Members: swp1(UP), swp2(UP)
UP  bridge         None      N/A       1500  Bridge/L2                                 Untagged Members: bond1, swp3-5
UP  peerlink       None      1G        1500  Bond                                      Bond Members: swp11(UP)
UP  peerlink.4093  None      1G        1500  SubInt/L3                                 IP: 169.254.1.1/30

[email protected]:~$ net show lldp

LocalPort    Speed    Mode        RemotePort    RemoteHost    Summary
-----------  -------  ----------  ------------  ------------  ----------------------
eth0         1G       Mgmt        eth0          cumulus       IP: 192.168.100.207/24
                                  ====          eth0          spine-2
                                  ====          eth0          spine-1
                                  ====          eth0          leaf-2
swp1         1G       BondMember  swp1          spine-1       Master: bond1(UP)
swp2         1G       BondMember  swp1          spine-2       Master: bond1(UP)
swp11        1G       BondMember  swp11         leaf-2        Master: peerlink(UP)
[email protected]:~$

As you can see the configuration is correctly deployed and you can start testing.

The configuration for a real datacentre Fabric is of course, more complex (multiple VRFs, SVIs and complex Routing) but with Ansible you can quickly deploy and manage hundreds of switches.

In one of the next posts, I will write an Ansible Playbook for a Layer 3 datacentre Fabric configuration using BGP and ECMP routing on Quagga.

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