Multi-Platform Custom Configuration Templates in netsim-tools
In the Building a BGP Anycast Lab I described how you could use custom configuration templates to extend the functionality of netsim-tools.
That example used Cisco IOS… but what if you want to test the same functionality on multiple platforms? netsim-tools provides a nice trick: the custom configuration template could point to a directory with platform-specific templates. Let me show you how that works…
We’ll start with the BGP anycast topology, but change the lab devices to a mix of Cisco IOS, Arista EOS, and Cumulus VX:
- Most devices will run Cisco IOSv
- One of the leaf switches and one of the anycast nodes will run Arista EOS
- Another anycast node will run Cumulus VX
Physical lab topology
module: [ ospf, bgp ]
defaults.bgp.extra_attributes.node: [ anycast ]
bgp:
as_list:
65000:
members: [ l1, l2, l3, s1 ]
rr: [ s1 ]
65101:
members: [ a1,a2,a3 ]
defaults.device: iosv
nodes:
l1:
l2:
device: eos
l3:
s1:
a1:
a2:
device: eos
a3:
device: cumulus
links: [ s1-l1, s1-l2, s1-l3, l2-a1, l2-a2, l3-a3 ]
Now for the multi-platform custom configuration trick: we’ll specify directories instead of template file names in group config attributes (read the BGP anycast blog post for more details).
groups:
as65000:
config: [ bgp-addpath ]
as65101:
config: [ bgp-anycast ]
node_data:
bgp.anycast: 10.42.42.42/32
bgp.advertise_loopback: False
The final lab topology file is available on GitHub.
We’ll have three files within the bgp-anycast directory: ios.j2, eos.j2 and cumulus.j2:
{% if bgp is defined and bgp.anycast is defined %}
interface loopback 42
ip address {{ bgp.anycast|ipaddr('address') }} {{ bgp.anycast|ipaddr('netmask') }}
!
router bgp {{ bgp.as }}
address-family ipv4
network {{ bgp.anycast|ipaddr('address') }} mask {{ bgp.anycast|ipaddr('netmask') }}
{% endif %}
{% if bgp is defined and bgp.anycast is defined %}
interface loopback 42
ip address {{ bgp.anycast }}
!
router bgp {{ bgp.as }}
address-family ipv4
network {{ bgp.anycast|ipaddr('0') }}
{% endif %}
{% if bgp is defined and bgp.anycast is defined %}
interface lo
ip address {{ bgp.anycast }} label anycast
!
router bgp {{ bgp.as }}
address-family ipv4
network {{ bgp.anycast|ipaddr('0') }}
{% endif %}
Ansible playbook printout generated during the lab initialization (using netlab up -q command) displays the templates used to configure lab devices – as you can see, every platform uses a different configuration template.
# ios_config: deploying bgp-anycast from /home/pipi/net101/multi-platform/bgp-anycast/bgp-anycast/ios.j2 ******************
* a1 - changed=True -- ---------------------------------------------
...
# eos_config: deploying bgp-anycast from /home/pipi/net101/multi-platform/bgp-anycast/bgp-anycast/eos.j2 ******************
* a2 - changed=True -- ---------------------------------------------
.....
# run vtysh to import bgp-anycast config from /home/pipi/net101/multi-platform/bgp-anycast/bgp-anycast/cumulus.j2 *********
* a3 - changed=True -- ---------------------------------------------
...
# ios_config: deploying bgp-addpath from /home/pipi/net101/multi-platform/bgp-anycast/bgp-addpath/ios.j2 ******************
* l1 - changed=True -- ---------------------------------------------
...
# eos_config: deploying bgp-addpath from /home/pipi/net101/multi-platform/bgp-anycast/bgp-addpath/eos.j2 ******************
* l2 - changed=True -- ---------------------------------------------
...
# ios_config: deploying bgp-addpath from /home/pipi/net101/multi-platform/bgp-anycast/bgp-addpath/ios.j2 ******************
* l3 - changed=True -- ---------------------------------------------
...
# ios_config: deploying bgp-addpath from /home/pipi/net101/multi-platform/bgp-anycast/bgp-addpath/ios.j2 ******************
* s1 - changed=True -- ---------------------------------------------
Want to test this functionality on your own? Install netsim-tools (and a bunch of other stuff), download the lab topology and custom configuration templates from GitHub, and execute netlab up.