Feature Behavior - Alcatel-Lucent 7450 Manual

Label Distribution Protocol
applied to a given peer prefix are taken from the first created template by the user. This provides a
more deterministic behavior regardless of the order in which the templates are associated with the
prefix policies.
Each time the user executes the above command, with the same or different prefix policy
associations, or the user changes a prefix policy associated with a targeted peer template, the
system re-evaluates the prefix policy. The outcome of the re-evaluation will tell LDP if an existing
targeted Hello adjacency needs to be torn down or if an existing targeted Hello adjacency needs to
have its parameters updated on the fly.
If a /32 prefix is added to (removed from) or if a prefix range is expanded (shrunk) in a prefix list
associated with a targeted peer template, the same prefix policy re-evaluation described above is
performed.
The template comes up in the no shutdown state and as such it takes effect immediately. Once a
template is in use, the user can change any of the parameters on the fly without shutting down the
template. In this case, all targeted Hello adjacencies are.
There is no overall chassis mode restrictions enforced with the auto-created T-LDP session
feature. If the chassis-mode, network chassis-mode or IOM type requirements for an LDP feature
are not met, the configuration of the corresponding command will not be allowed as in existing
implementation.

Feature Behavior

Whether the prefix list contains one or more specific /32 addresses or a range of addresses, an
external trigger is required to indicate to LDP to instantiate a targeted Hello adjacency to a node
which address matches an entry in the prefix list. The objective of the feature is to provide an
automatic creation of a T-LDP session to the same destination as an auto-created RSVP LSP to
achieve automatic tunneling of LDP-over-RSVP. The external trigger is when the router with the
matching address appears in the Traffic Engineering database. In the latter case, an external
module monitoring the TE database for the peer prefixes provides the trigger to LDP. As a result
of this, the user must enable the traffic-engineering option in ISIS or OSPF.
Each mapping of a targeted session peer parameter template to a policy prefix which exists in the
TE database will result in LDP establishing a targeted Hello adjacency to this peer address using
the targeted session parameters configured in the template. This Hello adjacency will then either
7450 ESS MPLS Guide Page 567