The value of tBgpInstanceDisallowIgp specifies if IGP next-hop to the
BGP next-hop is used as the next-hop of the last resort.
A value of 'true', disallows the IGP next-hop to the BGP next-hop from
being used as the next-hop of the last resort. This is used to prevent
routing loops.
A value of 'false' reverts the IGP shortcut next-hop evaluation process
to the default of allowing IGP next-hops as the next-hop of the last
resort.