@Fred Stanton
All the routes have the same next hop (100.100.1.2). This indicates that the routes to the destination 200.0.0.0 are reachable through the same next hop router, which is common in BGP scenarios when multiple routes are learned from different BGP peers.
Also, if the router that's advertising the route is not setting a MED for all paths, only the ones where it's configured will show a metric other than zero.
In your BGP scenario, you are observing multiple eBGP peers on the same network segment (100.100.1.2), which is common when different routers advertise routes for the same destination (`200.0.0.0`) while using the same next hop. This behavior, known as the third-party next-hop feature, allows BGP to simplify routing information by indicating that multiple peers are directly reachable and thus advertising the next hop of the originating eBGP peer. The presence of a metric value only on one of the paths indicates that this metric, known as the MED, was set by the originating router before it advertised the route to your router, showing its internal cost for reaching the prefix. The other routes, when re-advertised by different routers, do not carry this MED because BGP does not propagate MED values for routes it has not originated, as these routers lack knowledge of the originating AS's internal cost metrics. Therefore, while you see the same next hop for all routes, the metric is only present for the route that originated from the eBGP peer that defined it, demonstrating how BGP manages route advertisements and metrics in multi-homed environments.
Best regards
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