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Cisco 10000 Series Router Quality of Service Configuration Guide
OL-7433-09
Chapter 9 Shaping Traffic
Traffic Shaping
Feature History for Class-Based Traffic Shaping
System Limits for Class-Based Shaping
Table 3-1 on page 3-2
lists the system limits for policy maps supported on the Cisco 10000 series router.
Restrictions and Limitations for Class-Based Shaping
•
A single policy map can be attached to multiple interfaces concurrently. If you attempt to attach a
policy map to an interface when the sum of the bandwidth assigned to classes is greater than 99
percent of the available bandwidth, the router logs a warning message and does not allocate the
requested bandwidth to all of the classes. If the policy map is already attached to other interfaces, it
is removed from them.
•
Whenever you modify a class policy in an attached policy map, class-based weighted fair queuing
(CBWFQ) is notified and the new classes are installed as part of the policy map in the CBWFQ
system.
Hierarchical Shaping
Hierarchical shaping provides two levels of shaping—per-VC ATM-level shaping and per-VC
packet-level shaping—and provides per-VC and per-VP traffic shaping to control or modify the flow of
traffic on an interface. Traffic shaping limits throughput by buffering excess traffic instead of dropping
packets. The shaping function also ensures that traffic from one VC does not adversely impact another
VC, resulting in loss of data.
The Cisco 10000 series router supports hierarchical shaping for the following ATM line cards:
•
OC-12
•
4-port OC-3
•
8-port E3/DS3
The router supports hierarchical shaping when operating as a Layer 2 Access Concentrator (LAC) and
in the following modes:
•
PPP termination and aggregation (PTA)
•
Router bridge encapsulation (RBE)
•
RFC 1483
Hierarchical shaping does not require that you configure policy maps. You can use hierarchical shaping
with non-queuing related policy maps configured in a virtual template or configured directly on the VC.
Apply queuing-related policy maps directly to the VC.
Cisco IOS Release
Description
Required PRE
Release 12.0(25)SX
The Class-Based Traffic Shaping feature was introduced
on the router.
PRE1
Release 12.2(16)BX
This feature was introduced on the PRE2.
PRE2
Release 12.2(28)SB
This feature was integrated in Cisco IOS
Release 12.2(28)SB for the PRE2.
PRE2
Release 12.2(31)SB2
This feature was introduced on the PRE3.
PRE3