HP VPN Firewall Appliances Network Management Configuration Guide

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Figure 181 Rate limit implementation
In the token bucket approach to traffic control, bursty traffic can be transmitted as long as enough tokens
are available in the token bucket. If tokens are inadequate, packets cannot be transmitted until the system
generates the required number of tokens in the token bucket. The traffic rate is restricted to the rate for
generating tokens. The traffic rate is limited, and bursty traffic is allowed.
Configuring a QoS policy in the Web interface
Configuration guidelines
When you configure a QoS policy, follow these guidelines:
• How an ACL referenced by a QoS policy is handled depends on whether the policy is applied to
a software interface or a hardware interface.
{ If the QoS policy is applied to a software interface, only the permit statements in the referenced
ACL will take effect, and the deny statements in the referenced ACL will be ignored.
{ If the QoS policy is applied to a hardware interface, packets matching the ACL are organized
as a class and the behavior defined in the QoS policy applies to the class regardless of whether
the referenced ACL is a deny or permit clause.
• The QoS policy applied in the outbound direction of a port does not take effect on local PDUs. Local
PDUs are packets sent by the protocols essential to device operation from the local device, such as
link maintenance packets like ISIS, OSPF, RIP, BGP, LDP, RSVP, and SSH. Because drop of local
PDUs might cause anomalies, QoS is designed not to regulate local PDUs.