Overview Of Rsvp For Mpls-Te Features; Configuring Rsvp For Mpls-Te; Configuring Rsvp Message Authentication Globally - Cisco NCS 5500 Series Configuration Manual

Overview of RSVP for MPLS-TE Features

previous node. The reservation state in each router is considered as a soft state, which means that periodic
PATH and RESV messages must be sent at each hop to maintain the state.
When the reservation message arrives at the previous node, it causes the reserved resources to be locked and
forwarding entries are programmed with the MPLS label sent from the tail-end node. A new MPLS label is
allocated and sent to the next node upstream. When the reservation message reaches the head node, the label
is programmed and the MPLS data starts to flow along the path.
Overview of RSVP for MPLS-TE Features
This section provides an overview of the various features of RSVP for MPLS-TE.
RSVP is automatically enabled on interfaces on which MPLS-TE is configured. For MPLS-TE LSPs with
bandwidth, the RSVP bandwidth has to be configured on the interfaces. There is no need to configure RSVP,
if all MPLS-TE LSPs have zero bandwidth.
RSVP Graceful restart ensures high availability and allows RSVP TE enabled routers to recover RSVP state
information from neighbors after a failure in the network.
RSVP requires that the path and reservation state that are set up during LSP signaling must be refreshed by
periodically sending refresh messages. Refresh messages are used to synchronize the state between RSVP
neighbors and to recover from lost RSVP messages. RSVP refresh reduction feature includes support for
reliable messages which are transmitted rapidly when the messages are lost. Summary refresh messages
contain information to refresh multiple states and reduces the number of messages required to refresh states.
RSVP messages can be authenticated to ensure that only trusted neighbors can set up reservations.
For detailed information about RSVP for MPLS-TE features, see
page

Configuring RSVP for MPLS-TE

RSVP requires coordination among several routers, establishing exchange of RSVP messages to set up LSPs.
To configure RSVP, you need to install the following two RPMs :
• ncs5500-mpls-2.0.0.0-r601.x86_64.rpm-6.0.1
• ncs5500-mpls-te-rsvp-2.0.0.0-r601.x86_64.rpm-6.0.1
Depending on the requirements, RSVP requires some basic configuration described in the following topics:

Configuring RSVP Message Authentication Globally

The RSVP authentication feature permits neighbors in an RSVP network to use a secure hash algorithm to
authenticate all RSVP signaling messages digitally. The authentication is accomplished on a per-RSVP-hop
basis using an RSVP integrity object in the RSVP message. The integrity object includes a key ID, a sequence
number for messages, and keyed message digest.
You can globally configure the values of authentication parameters including the key-chain, time interval that
RSVP maintains security associations with other trusted RSVP neighbors (life time) and maximum number
of RSVP authenticated messages that can be received out of sequence (window size). These defaults are
inherited for each neighbor or interface.
MPLS Configuration Guide for Cisco NCS 5500 Series Routers, IOS XR Release 6.2.x
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Implementing RSVP for MPLS-TE
RSVP for MPLS-TE Features- Details, on