With 'no bgp default ipv4-unicast' set at the router level, VRF gold
eBGP/iBGP neighbors were establishing but not exchanging any IPv4
prefixes, breaking inter-fabric transit between DC and Campus. Add an
explicit 'address-family ipv4' block with 'neighbor X activate' under
'vrf gold' on both cores and all four border leafs.
Also drop 'redistribute learned' from the border leaf VRF gold stanza:
it is not a valid command in that context and was silently stripped by
EOS.
core1/core2 provide L3 transit between DC and Campus fabrics. Each
physical link toward a Border Leaf is subinterfaced (.100 default,
.200 VRF gold). OSPF area 0 in default VRF, eBGP to DC BLs (65005)
and Campus BLs (66005), iBGP between core1 and core2 via Loopback0.
VRF gold uses redistribute connected and VRF-aware eBGP sessions on
.200 subinterfaces to stitch VRF gold end-to-end across fabrics.
