Alcatel-Lucent 7450 Manual page 289

When Diff-Serv TE is enabled, the system will automatically enable the Max Allocation Model
(MAM) Admission Control Policy. MAM represents the bandwidth constraint model for the
admission control of an LSP reservation to a link. This is the only Admission Control Policy
supported in this release.
Each CT shares a percentage of the Maximum Reservable Link Bandwidth via the user configured
Bandwidth Constraint (BC) for this CT. The Maximum Reservable Link Bandwidth is the link
bandwidth multiplied by the RSVP interface subscription factor.
The sum of all BC values across all CTs will not exceed the Maximum Reservable Link Bandwidth.
In other words, the following rule is enforced:
An LSP of class-type CTc, setup priority p, holding priority h (h=<p), and bandwidth B is admitted
into a link if the following condition is satisfied:
where TE-Class [i] maps to < CTc , p > in the definition of the TE classes on the node. The
bandwidth reservation is effected at the holding priority, i.e., in TE-class [j] = <CTc, h>. Thus, the
reserved bandwidth for CTc and the unreserved bandwidth for the TE classes using CTc are updated
as follows:
The same is done to update the unreserved bandwidth for any other TE class making use of the same
CTc. These new values are advertised to the rest of the network at the next IGP-TE flooding.
The Russian Doll Model (RDM) LSP admission control policy allows bandwidth sharing across
Class Types. It provides a hierarchical model by which the reserved bandwidth of a CT is the sum of
the reserved bandwidths of the numerically equal and higher CTs.
The RDM model is defined using the following equations:
where the SUM is across all values of c in the range b <= c <= (MaxCT - 1), and BCb is the
bandwidth constraint of CTb.
where the SUM is across all values of c in the range 0 <= c <= (MaxCT - 1).
When Diff-Serv is disabled on the node, this model degenerates into a single default CT internally
with eight pre-emption priorities and a non-configurable BC equal to the Maximum Reservable Link
Bandwidth. This would behave exactly like CT0 with eight pre-emption priorities and BC=
Maximum Reservable Link Bandwidth if Diff-Serv was enabled.
The enabling or disabling of Diff-Serv TE on the system requires the RSVP and MPLS protocol be
shutdown.
The no form of this command reverts to the default value.
7450 ESS MPLS Guide
• Configuration of the percentage of RSVP interface bandwidth each CT shares, i.e., the Band-
width Constraint (BC).
SUM (BCc) =< Max-Reservable-Bandwidth, 0 <= c <= 7
B <= Unreserved Bandwidth for TE-Class[i]
Reserved(CTc) = Reserved(CTc) + B
Unreserved TE-Class [j] = BCc - SUM (Reserved(CTc,q)) for 0<= q <= h
Unreserved TE-Class [i] = BCc - SUM (Reserved(CTc,q)) for 0<= q <= p
SUM (Reserved (CTc)) <= BCb,
BC0= Max-Reservable-Bandwidth, so that
SUM (Reserved(CTc)) <= Max-Reservable-Bandwidth,
MPLS and RSVP
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