HP FlexNetwork 10500 Series Configuration Manual page 88

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IETF mode—Complies with RFC 4124, RFC 4125, and RFC 4127.
Basic concepts
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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.
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BC—Bandwidth Constraint. BC restricts the bandwidth for one or more CTs.
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Bandwidth constraint model—Algorithm for implementing bandwidth constraints on different
CTs. A BC model contains two factors, the maximum number of BCs (MaxBC) and the
mappings between BCs and CTs. DS-TE supports two BC models, Russian Dolls Model (RDM)
and Maximum Allocation Model (MAM).
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TE class—Defines a CT and a priority. The setup priority or holding priority of an MPLS TE
tunnel for a CT must be the same as the priority of the TE class.
The prestandard and IETF modes of DS-TE have the following differences:
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The prestandard mode supports two CTs (CT 0 and CT 1), eight priorities, and a maximum of 16
TE classes. The IETF mode supports four CTs (CT 0 through CT 3), eight priorities, and a
maximum of eight TE classes.
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The prestandard mode does not allow you to configure TE classes. The IETF mode allows for
TE class configuration.
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The prestandard mode supports only RDM. The IETF mode supports both RDM and MAM.
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A device operating in prestandard mode cannot communicate with devices from some vendors.
A device operating in IETF mode can communicate with devices from other vendors.
How DS-TE operates
A device takes the following steps to establish an MPLS TE tunnel for a CT:
1. Determines the CT.
A device classifies traffic according to your configuration:
When configuring a dynamic MPLS TE tunnel, you can use the mpls te bandwidth

command on the tunnel interface to specify a CT for the traffic to be forwarded by the tunnel.
When configuring a static MPLS TE tunnel, you can use the bandwidth keyword to specify

a CT for the traffic to be forwarded along the tunnel.
2. Verifies that bandwidth is enough for the CT.
You can use the mpls te max-reservable-bandwidth command on an interface to configure
the bandwidth constraints of the interface. The device determines whether the bandwidth is
enough to establish an MPLS TE tunnel for the CT.
The relation between BCs and CTs varies by BC model.
In RDM model, a BC constrains the total bandwidth of multiple CTs, as shown in
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−
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In cooperation with priority preemption, the RDM model can also implement bandwidth
isolation between CTs. RDM is suitable for networks where traffic is unstable and traffic
bursts might occur.
BC 2 is for CT 2. The total bandwidth for CT 2 cannot exceed BC 2.
BC 1 is for CT 2 and CT 1. The total bandwidth for CT 2 and CT 1 cannot exceed BC 1.
BC 0 is for CT 2, CT 1, and CT 0. The total bandwidth for CT 2, CT 1, and CT 0 cannot
exceed BC 0. In this model, BC 0 equals the maximum reservable bandwidth of the link.
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Figure 30: