RTG-DIR Issue 5: Introduction (Section 1) in paragraph 13
Text:/
In some situations, it is undesirable for a controller or BGP egress
router to have a BGP session to each policy headend. In these
situations, BGP Route Reflectors may be used to propagate the
advertisements. In certain other deployments, it may be necessary
for the advertisement to propagate through a sequence of one or more
ASes within an SR Domain (refer to Section 7 for the associated
security considerations). To make this possible, an attribute needs
to be attached to the advertisement that enables a BGP speaker to
determine whether it is intended to be a headend for the advertised
policy. This is done by attaching one or more Route Target Extended
Communities to the advertisement [RFC4360]./
Jeffrey Question: How is further propagation prevented after the headend is reached?
RTG-DIR Issue 5: Introduction (Section 1) in paragraph 13
Text:/ In some situations, it is undesirable for a controller or BGP egress router to have a BGP session to each policy headend. In these situations, BGP Route Reflectors may be used to propagate the advertisements. In certain other deployments, it may be necessary for the advertisement to propagate through a sequence of one or more ASes within an SR Domain (refer to Section 7 for the associated security considerations). To make this possible, an attribute needs to be attached to the advertisement that enables a BGP speaker to determine whether it is intended to be a headend for the advertised policy. This is done by attaching one or more Route Target Extended Communities to the advertisement [RFC4360]./
Jeffrey Question: How is further propagation prevented after the headend is reached?