Using Rsvp For Mpls; Rsvp Traffic Engineering Extensions For Mpls; Hello Protocol - Alcatel-Lucent 7450 Manual

Using RSVP for MPLS

Using RSVP for MPLS

Hosts and routers that support both MPLS and RSVP can associate labels with RSVP flows. When
MPLS and RSVP are combined, the definition of a flow can be made more flexible. Once an LSP
is established, the traffic through the path is defined by the label applied at the ingress node of the
LSP. The mapping of label to traffic can be accomplished using a variety of criteria. The set of
packets that are assigned the same label value by a specific node are considered to belong to the
same FEC which defines the RSVP flow.
For use with MPLS, RSVP already has the resource reservation component built-in which makes it
ideal to reserve resources for LSPs.

RSVP Traffic Engineering Extensions for MPLS

RSVP has been extended for MPLS to support automatic signaling of LSPs. To enhance the
scalability, latency, and reliability of RSVP signaling, several extensions have been defined.
Refresh messages are still transmitted but the volume of traffic, the amount of CPU utilization, and
response latency are reduced while reliability is supported. None of these extensions result in
backward compatibility problems with traditional RSVP implementations.

Hello Protocol

The Hello protocol detects the loss of a neighbor node or the reset of a neighbor's RSVP state
information. In standard RSVP, neighbor monitoring occurs as part of RSVP's soft-state model.
The reservation state is maintained as cached information that is first installed and then
periodically refreshed by the ingress and egress LSRs. If the state is not refreshed within a
specified time interval, the LSR discards the state because it assumes that either the neighbor node
has been lost or its RSVP state information has been reset.
The Hello protocol extension is composed of a hello message, a hello request object and a hello
ACK object. Hello processing between two neighbors supports independent selection of failure
detection intervals. Each neighbor can automatically issue hello request objects. Each hello
request object is answered by a hello ACK object.
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