59
Figure 26 MAM bandwidth constraints model
3.
Checks whether the CT and the LSP setup/holding priority match an existing TE class.
An MPLS TE tunnel can be established for the CT only when the following conditions are met:
Every node along the tunnel has a TE class that matches the CT and the LSP setup priority.
Every node along the tunnel has a TE class that matches the CT and the LSP holding
priority.
Bidirectional MPLS TE tunnel
MPLS Transport Profile (MPLS-TP) uses bidirectional MPLS TE tunnels to implement 1:1 and 1+1
protection switching and support in-band detection tools and signaling protocols such as OAM and
PSC.
A bidirectional MPLS TE tunnel includes a pair of CRLSPs in opposite directions. It can be
established in the following modes:
•
Co-routed mode
—Uses the extended RSVP-TE protocol to establish a bidirectional MPLS TE
tunnel. RSVP-TE uses a Path message to advertise the labels assigned by the upstream LSR
to the downstream LSR and a Resv message to advertise the labels assigned by the
downstream LSR to the upstream LSR. During the delivery of the path message, a CRLSP in
one direction is established. During the delivery of the Resv message, a CRLSP in the other
direction is established. The CRLSPs of a bidirectional MPLS TE tunnel established in
co-routed mode use the same path.
•
Associated mode
—In this mode, you establish a bidirectional MPLS TE tunnel by binding two
unidirectional CRLSPs in opposite directions. The two CRLSPs can be established in different
modes and use different paths. For example, one CRLSP is established statically and the other
CRLSP is established dynamically by RSVP-TE.
For more information about establishing MPLS TE tunnel through RSVP-TE, the Path message, and
the Resv message, see "
."
Protocols and standards
•
RFC 2702,
Requirements for Traffic Engineering Over MPLS
•
RFC 3564,
Requirements for Support of Differentiated Service-aware MPLS Traffic
Engineering
•
RFC 4124,
Protocol Extensions for Support of Diffserv-aware MPLS Traffic Engineering
•
RFC 4125,
Maximum Allocation Bandwidth Constraints Model for Diffserv-aware MPLS Traffic
Engineering
•
RFC 4127,
Russian Dolls Bandwidth Constraints Model for Diffserv-aware MPLS Traffic
Engineering
CT 2
CT 1
CT 0
BC 0
Max reservable BW
BC 1
BC 2
CT 0
CT 1
CT 2