"show ip bgp sum" is present in 1.4, but "show ipv6 bgp ..." is missing.
vtysh show ip bgp ipv6 sum
"show ip bgp sum" is present in 1.4, but "show ipv6 bgp ..." is missing.
vtysh show ip bgp ipv6 sum
When on VyOS 1.4 please use the show bgp ipv6 command as exposed by FRR. The show ip bgp command is only kept as not all options from show ip bgp are exposed in FRR under the show bgp ipv4 tree.