Diffserv-aware te, Overview, Basic concepts – H3C Technologies H3C SR8800 User Manual
Page 63
52
force (forced switch)—Forces data to travel on the backup LSP.
manual (manual switch)—Switches data from the main LSP to the backup LSP or vice versa.
2.
Signal switching (Signal Fail) refers to a PS automatically triggered by a signal fail declaration.
Examples include a PS that occurs during BFD detection for MPLS-TE tunnels.
In practice, a switching command takes effect only when its priority is higher than that of a signal
fail declaration.
The following shows the priority of the externally configured switching actions and the signal fail
switching, in the descending order:
Clear
Lockout of protection
Forced switch
Signal fail
Manual switch
DiffServ-aware TE
Overview
Diff-Serv 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 them to optimize network resources allocation at a per-service class
level. For traffic trunks which are distinguished by class of service, this means varied bandwidth
constraints. Essentially, what DS-TE does is to map traffic trunks with LSPs, making each traffic trunk
traverse the constraints-compliant path.
The router supports the following DS-TE modes:
•
Prestandard mode—Implemented by using H3C proprietary mechanisms
•
IETF mode—Implemented according to RFC 4124, RFC 4125, and RFC 4127.
Basic concepts
•
Class Type (CT): A set of traffic trunks crossing a link that is governed by a specific set of bandwidth
constraints. DS-TE allocates link bandwidth, implements constraint-based routing, and performs
admission control for a traffic trunk according to the traffic trunk’s CT. A given traffic trunk belongs
to the same CT on all links.
•
Bandwidth Constraint (BC): Restricts the bandwidth for one or more class types.
•
Bandwidth constraints model: Algorithm for implementing bandwidth constraints on different CTs.
A BC model comprises two factors, the maximum number of Bandwidth Constraints (MaxBC) and
the mappings between BCs and CTs. DS-TE supports two BC models, Russian Dolls Model (RDM)
and Maximum Allocation Model (MAM).
•
TE class: A pair consisting of a CT and a preemption priority for the CT. The setup priority or
holding priority of an LSP transporting a traffic trunk from that CT must be the preemption priority for
the CT.