Understanding The Benefits Of Policers And Token Bucket Algorithms; Scenario 1: Single Tcp Connection - Juniper EX9200 Features Manual

Traffic Policers Feature Guide for EX9200 Switches
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Understanding the Benefits of Policers and Token Bucket Algorithms

Scenario 1: Single TCP Connection

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NOTE: The measured length of a packet changes according to the family
type that the policer applies to. If the policer is applied under the
hierarchy, the policer considers only the IPv4 packet length. If the policer is
applied under the
the Ethernet MAC header) is included in the packet length.
The major factor that affects the policer shaping result is not the conversion adjustment,
but the traffic pattern since most network traffic is not consistent and is not sent at a
constant rate. Due to the fluctuation of the incoming traffic rate, some of the allocated
tokens are not used. As a result, the shaped traffic rate is lower than you might expect,
and the TCP connection behavior discussed in
and Token Bucket Algorithms" on page 28
effect of the lower shaped traffic rate, a proper burst size configuration is required.
Understanding the Benefits of Policers and Token Bucket Algorithms on page 28
Determining Proper Burst Size for Traffic Policers on page 30
This topic describes some scenarios that demonstrate how difficult it is to control traffic
that comes into your network without the help of policers and the token bucket algorithm.
These scenarios assume that traffic is coming from a TCP-based connection. Depending
on the number of TCP connections, policers can have different affects on rate limits.
This topic presents the following scenarios:
Scenario 1: Single TCP Connection on page 28
Scenario 2: Multiple TCP Connections on page 29
Figure 5 on page 29 shows the traffic loading on an interface with a policer configured.
When the traffic rate reaches the configured bandwidth limit (which results in a packet
drop), a TCP slow-start mechanism reduces the traffic rate down to half of what it was.
When the traffic rate rises again, the same cycle repeats.
family vpls hierarchy, the entire Ethernet frame (including
"Understanding the Benefits of Policers
is a typical example of this. To alleviate this
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family inet