The Cisco documentation about this call it Inter-AS Option B with the use case being to extend LSPs between sites over the one link. As Option B is the only MPLS-VPN method supported by Cisco SD-WAN I wanted to get a better understanding of how it works aswell as see if it could be used to extend multi-VRF prefixes between edge routers and a core switch within the same AS (rather than using Option C with LDP).
Recently whilst using pynetbox to create NetBox environment objects I had a need to use variables in the URL of the API calls to allow for reusable functions to perform API calls based on the URL and data fed in as arguments. The reason the URL needs to be fed in as an argument when calling the function is because each NetBox element uses a different API URL.
This post goes through how to configure MPLS VPN on the service-side of a Cisco SD-WAN edge device, so the south-side towards non-SD-WAN devices. What I am trying to achieve is to advertise the differing SD-WAN VPN (VRF, why Cisco have to call these VPNs beats me) prefixes to a core switch (using a ASR in the lab) directly connected to the SD-WAN router. This could be accomplished using per-VRF interfaces (or sub-interfaces) and BGP peerings, but a neater solution is to pass all the routing information over one the BGP MPLS VPNv4 peering.
As part of a POC I deployed a pair of HA F5 LTM/GTM at home to use for all things DNS based. It is an indulgent over the top DNS solution for a 1 bed flat, but hey-ho we are in a pandemic….. This guide does not go through the HA F5 or GTM (still cant stop calling it that) configuration, it is focussed around using ZoneRunner for DNS (bind) with these zones transferred into DNS express and serviced by a listener.