Alcatel-Lucent 7450 Manual page 525

In the router, the adjacency management is done through the establishment of a Service
Distribution Path (SDP) object, which is a service entity in the Alcatel-Lucent service model.
The Alcatel-Lucent service model uses logical entities that interact to provide a service. The
service model requires the service provider to create configurations for four main entities:
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An SDP is the network-side termination point for a tunnel to a remote router. An SDP defines a
local entity that includes the system IP address of the remote routers and a path type. Each SDP
comprises:
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If the SDP is identified as using LDP signaling, then an LDP extended hello adjacency is
attempted.
If another SDP is created to the same remote destination, and if LDP signaling is enabled, no
further action is taken, since only one adjacency and one LDP session exists between the pair of
nodes.
An SDP is a uni-directional object, so a pair of SDPs pointing at each other must be configured in
order for an LDP adjacency to be established. Once an adjacency is established, it is maintained
through periodic hello messages.
Session Establishment
When the LDP adjacency is established, the session setup follows as per the LDP specification.
Initialization and keepalive messages complete the session setup, followed by address messages to
exchange all interface IP addresses. Periodic keepalives or other session messages maintain the
session liveliness.
7450 ESS MPLS Guide
Customers
Services
Service Access Paths (SAPs) on the local routers
Service Distribution Points (SDPs) that connect to one or more remote routers.
The SDP ID
The transport encapsulation type, either MPLS or GRE
The far-end system IP address
Label Distribution Protocol
Page 525