Feature History For Hierarchical Shaping; Vp-Level Shaping; Vc-Level Shaping; Shaped Ubr Pvcs - Cisco 10000 Series Configuration Manual

Chapter 9 Shaping Traffic
Hierarchical shaping supports the range pvc command to define shaping for a range of PVCs and the
vc-class atm command to create a VC class with shaping defined for a PVC.

Feature History for Hierarchical Shaping

Cisco IOS Release
Release 12.3(7)XI
Release 12.2(28)SB
Release 12.2(31)SB2

VP-Level Shaping

The segmentation and reassembly (SAR) mechanism of the Cisco 10000 series router handles VP-level
shaping functions, based on the aggregate VP traffic. VP shaping regulates the output rate of the VP
tunnel, rather than the output rate of the individual VCs. The SAR limits the rate of the overall output of
the VP tunnel to the constant bit rate (CBR) with a peak cell rate (PCR) specified for the tunnel that is
compliant with VP-level shaping requirements.
The SAR sends the cells (from the VCs in the VP tunnel) into the tunnel based on a weighted round robin
format. The weight indicates the number of cells a VC can send into the tunnel before the SAR processes
the next VC. The line card software programs a weight that is proportional to the VC's rate. Only
variable bit rate (VBR) VCs are allowed in the tunnel.

VC-Level Shaping

The parallel express forwarding (PXF) engine of the Cisco 10000 series router handles the VC-level
shaping functions. The PXF shapes the VCs at the packet level, including all ATM overheads based on
the sustained cell rate (SCR). VC-level shaping ensures that the VC traffic stream averages to be no
greater than the SCR, but is not compliant with ATM level instantaneous shaping requirements.

Shaped UBR PVCs

Prior to Cisco IOS Release 12.3(7)XI2, you could configure shaped unspecified bit rate (UBR) PVCs
only when the no atm pxf queuing command is configured. In Cisco IOS Release 12.3(7)XI2 and later
releases, you can configure shaped UBR PVCs when the atm pxf queuing command is configured.
When you specify shaped UBR, the router sets up layer 3 scheduling for the UBR VC in the same fashion
as VBR and CBR VCs. The VC has its own VTMS link and a set of queues assigned to it. The rate of
the link is based on the PCR you specify. Flowbits are assigned to the VC. Unlike VBR and CBR VCs,
only a single flowbit is assigned to the VC; it is not based on rate.
Like VBR and CBR VCs, the shaped UBR VCs can have queuing service policies applied to them. The
UBR VCs are not subject to any CAC checks, but the number of shaped UBR VCs must be within
existing limits, which include the maximum number of VCs per system, maximum number of VCs per
port, and maximum number of VCs with flowbits.
OL-7433-09
Description
The Hierarchical Shaping and ATM VC/VP Shaping
features were introduced on the router.
This feature was integrated in Cisco IOS
Release 12.2(28)SB for the PRE2.
This feature was introduced on the PRE3.
Cisco 10000 Series Router Quality of Service Configuration Guide
Traffic Shaping
Required PRE
PRE2
PRE2
PRE3
9-5