Traffic Shaping - Huawei Quidway S7700 Configuration Manual - Qos

Quidway S7700 Smart Routing Switch
Configuration Guide - QoS
l

2.1.2 Traffic Shaping

The traffic shaping function is used to control the rate of packets so that packets are sent at an
even rate. Traffic shaping is used to adapt the transmission rate of packets to the downstream
devices to prevent unnecessary packet loss and congestion.
Traffic shaping is a traffic control action used to limit traffic and resources by monitoring the
specification of the traffic. In traffic shaping, token buckets are also used to measure the traffic.
The traffic shaping technology limits the rate of outgoing traffic, and mainly controls the local
outgoing traffic based on the traffic policing specification of a downstream network node.
Difference Between Traffic Shaping and Traffic Policing
The main difference between traffic shaping and traffic policing is that the S7700 caches the
packets discarded in traffic policing. These packets are stored in a buffer or a queue, as shown
in Figure
out at an average rate.
Issue 01 (2011-07-15)
NOTE
l Aggregate CAR supports only the single token bucket.
l Traffic policing based on a traffic classifier on the S7700 implements interface-based and flow-
based rate limit in both directions. The matching rule is set to if-match any.
CPCAR
On a network, a large number of packets including valid packets and malicious attack
packets need to be delivered to the CPU. The malicious attack packets will affect other
services or even interrupt the system. Transmitting excess valid packets will also lead to
high CPU usage, which results in CPU performance deterioration and interrupts services.
To protect the CPU, limit the packets sent to the CPU. CPCAR performs traffic policing
on certain packets sent to the CPU, for example, host packets, blacklisted service flows,
and user-defined flows, to limit the transmission rate of the packets, protect the CPU, and
ensure running of the system.
When the traffic of host packets is heavy or a large number of malicious host packets are
sent, the system performance may deteriorate. To ensure that the system runs properly,
configure CPCAR on the S7700 to limit the traffic of host packets.
The S7700 can limit the traffic of packets that are sent to the CPU of the main control board
or LPU.
CPCAR uses the single token bucket.
For details about host packets, blacklisted flows, user-defined flows, and CPCAR
configuration, see Local Attack Defense Configuration in the Quidway S7700 Smart
Routing Switch Configuration Guide - Security.
2-2. When there are sufficient tokens in a token bucket, those cached packets are sent
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2 Traffic Policing and Traffic Shaping Configuration
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