A presentation by David Stockdale, network services team lead, Imperial College London, from Networkshop47.

1. David Stockdale
ICT Networks Group
david@imperial.ac.uk
Evolution of network automation at
Imperial College London

2. About Imperial
• 17,000 students
• 8,000 staff
• Main campus – South Kensington, London
• New campus – White City, London
• 6 other large campuses (hospitals, Silwood Park)
• 10+ other sites (hospitals, halls, sports grounds)
• 2 datacentres – Slough & South Ken
• Centralised ICT

3. Network
• Over 55,000 unique hosts on wired network
• Over 63,000 unique hosts on wireless network
• Over 24,000 concurrent wireless clients at peak time
• ~400 active comms rooms
• ~20 dark fibre links
• ~15 Ethernet circuits
• 2x 100G to Janet

4. Equipment
• Routers – 20x Juniper MX & 6x Cisco 6500/6880
• Smaller sites – 14x Juniper SRX 2xx/3xx
• Firewalls – 2x Juniper SRX 4600
• Switches – 2,000x Juniper & Extreme
• Wireless – 2,800x Cisco lightweight APs
• VoIP – 10,000x Cisco handsets

5. Network automation to date
• MAC based VLANs
• Firewall group memberships
• Switch config generation
• Load balancing
• Options have got better
– SNMP
– Expect, SCP
– APIs!

6. Meanwhile, on servers
• CFEngine2
– Management of ~100 Linux servers
– Served us well
– Discontinued (replaced by CFEngine3)
• Ansible
– Agentless
– Wealth of modules
– Python and Jinja2

7. The present
• MX/SRX routers
– Initially just VLANs/SVIs
– Facilitated migration from 6500s
– Now generating entire configs
• QFX/EX datacentre switches
– EVPN/VXLAN fabric
– Entire config except server-facing ports

8. Ansible components
• HDB – PostgreSQL
• Dynamic inventory – Python
• Variables, tasks, playbooks – YAML
• Templates – Jinja2
• Devices – netconf

11. all.yml
vlans_test:
- name: ANSIBLE-TEST
tag: 1000
- name: ANOTHER-TEST
tag: 1001
switch.j2
vlans {
{% for vlan in vlans_test %}
{{ vlan.name }} {
vlan-id {{ vlan.tag }};
}
{% endfor %}
}

13. The future
• HDB schema/GUI development
• Datacentre switch ports
• ZTP and Ansible for edge switches
• Distribution… older equipment

14. Closing thoughts
• Small steps
• Quick wins to reclaim time
• Standardisation
• Don’t forget how to troubleshoot!
• Any questions?