59
Figure 23
FRR link protection
•
Node protection
—The PLR and the MP are connected through a device and the primary CRLSP
traverses this device. When the device fails, traffic is switched to the bypass tunnel. As shown
in
, the primary CRLSP is Router A—Router B—Router C—Router D—Router E, and the
bypass tunnel is Router B—Router F—Router D. Router C is the protected device. This mode is also
called next-next-hop (NNHOP) protection.
Figure 24
FRR node protection
DiffServ-aware TE
DiffServ is a model that provides differentiated QoS guarantees based on class of service. MPLS TE is a
traffic engineering solution that focuses on optimizing network resources allocation.
DiffServ-aware TE (DS-TE) combines DiffServ and TE to optimize network resources allocation on a
per-service class basis. DS-TE defines different bandwidth constraints for class types. It maps each traffic
class type to the CRLSP that is constraint-compliant for the class type.
The device supports these DS-TE modes:
•
Prestandard mode
—HP proprietary DS-TE.
•
IETF mode
—Complies with RFC 4124, RFC 4125, and RFC 4127.
Basic concepts
•
CT
—Class Type. DS-TE allocates link bandwidth, implements constraint-based routing, and
performs admission control on a per class type basis. A given traffic flow belongs to the same CT
on all links.
•
BC
—Bandwidth Constraint. BC restricts the bandwidth for one or more CTs.
•
Bandwidth constraint model
—Algorithm for implementing bandwidth constraints on different CTs.
A BC model comprises two factors, the maximum number of BCs (MaxBC) and the mappings