It appears that while VyOS 1.4 supports static IPv6 route tags, VyOS 1.3 does not:
trae@cr01a-vyos# set protocols static route6 2607:f0d0:1234:123::/64 blackhole
Possible completions:
distance Distance value for this route
[edit]
trae@cr01a-vyos# set protocols static route6 2607:f0d0:1234:123::/64 blackhole tag 86
Configuration path: protocols static route6 2607:f0d0:1234:123::/64 blackhole [tag] is not valid
Set failedFRR itself appears to support it:
cr01b-vyos(config)# ipv6 route 2607:f0d0:1234:123::/64 Null0 tag (1-4294967295) Tag value
This prevents the use of static IPv6 routes for remotely triggered black holes. Can this functionality be added to 1.3?