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Chapter 9 Applications
Traffic Policing
Traffic policing is the limiting of the input or output transmission rate of a class of traffic on the basis of
user-defined criteria. Traffic policing methods measure traffic flows against user-defined criteria and
identify it as either conforming, exceeding or violating the criteria.
Traffic Rate
Traffic Rate
Time
Time
(Before Traffic Policing)
(After Traffic Policing)
The EMG2881-T20A supports three incoming traffic metering algorithms: Token Bucket Filter (TBF), Single
Rate Two Color Maker (srTCM), and Two Rate Two Color Marker (trTCM). You can specify actions which
are performed on the colored packets. See
Section 9.7 on page 83
for more information on each
metering algorithm.
NAT Traversal
UPnP NAT traversal automates the process of allowing an application to operate through NAT. UPnP
network devices can automatically configure network addressing, announce their presence in the
network to other UPnP devices and enable exchange of simple product and service descriptions. NAT
traversal allows the following:
• Dynamic port mapping
• Learning public IP addresses
• Assigning lease times to mappings
Windows Messenger is an example of an application that supports NAT traversal and UPnP.
See the NAT chapter for more information on NAT.
Cautions with UPnP
The automated nature of NAT traversal applications in establishing their own services and opening
firewall ports may present network security issues. Network information and configuration may also be
obtained and modified by users in some network environments.
When a UPnP device joins a network, it announces its presence with a multicast message. For security
reasons, the EMG2881-T20A allows multicast messages on the LAN only.
All UPnP-enabled devices may communicate freely with each other without additional configuration.
Disable UPnP if this is not your intention.
EMG2881-T20A User's Guide
77
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