Beta Draft Confidential
2-201/19/05 ATM Services Configuration Guide for CBX 3500, CBX 500, GX 550, and B-STDX 9000
About ATM Logical Ports
About VP Shaping on the CBX 500 and CBX 3500
If you leave the oversubscription factor set for the minimum value of 100%, the port
delivers all user data for that class of service (CoS) without unanticipated delays or
excessive cell loss. A value of 200% effectively doubles the virtual bandwidth
available for that CoS.
About VP Shaping on the CBX 500 and CBX 3500
Virtual path (VP) shaping provides the ability to shape OPTimum trunk connections at
a specified PCR while preserving QoS integrity. This feature ensures that the
maximum rate of the OPTimum trunk traffic does not exceed the specified PCR. See
either the CBX 500, CBX 3500, or Navis EMS-CBGX SRN for appropriate revision
levels.
On a CBX 3500 or CBX 500 switch, you can enable VP shaping only if the host IOM
is equipped with certain revisions of the ATM Flow Control Processor (FCP) module.
The FCP supports flow control or VP shaping on a per-logical port basis. See the
CBX 500, CBX 3500, or Navis EMS-CBGX SRN for appropriate revision levels.
Shaping is performed by assigning each VP a single queue on the FCP. Shaping is
performed on all cells belonging to the OPTimum trunk VP at the specified OPTimum
trunk shaping rate. Each of the VPs (tunnel VPs) are shaped at a rate that is different
from the opt-trunk shaping rate (SR) and does not consume it. You can configure the
tunnel VP shaping rate on the Tunnel VP Shaping Rate tab in the Add Logical Port
dialog box in Navis EMS-CBGX. One PCR is provisioned for the first VP of the LPort
and the aggregate traffic is scheduled with this rate. As a result, the aggregate rate of
the traffic on the first VP never exceeds the provisioned PVC rate. Four queues are
maintained for each shaped VP. The CBR queue has the highest priority, followed by
VBR-RT, VBR-NRT, and ABR/UBR queues. VCCs within a shaped VP are mapped
to the four queues according to their QoS.
Only VPCs provisioned through circuit defined path (CDP) are allowed to route
through OPTimum trunks. Use Mixed VNN/PNNI on the Path tab in the circuit
provisioning dialog box to provision the VPCs.
For additional information and configuration instructions, see “ILMI/OAM
Attributes” on page 3-34.
Note – Lucent reserves a certain percentage of bandwidth for network management,
routing updates, and other management traffic.
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