36. Traffic Control
ROX™ v2.2 User Guide
390
RuggedBackbone™ RX5000
36. Traffic Control
Traffic Control (TC) is a firewall subsystem managing the amount of bandwidth per network interface
that different types of traffic are permitted to use. For a traffic control configuration to work, a firewall
must be configured.
A ROX™ system allows up to 4 different firewall configurations, enabling you to quickly change between
configurations. You can quickly assess different configurations without needing to save and reload any
part of the configuration. In contrast, there is only one traffic control configuration. When enabled, a
traffic control configuration is used with the current firewall configuration. A current firewall configuration
is defined as one that is specified in either work-config and/or active-config. It does not have to be
enabled to be validated.
A TC configuration can be seen as an additional configuration that goes along with a current firewall
configuration. To actually add a TC configuration, it has to be enabled by setting the /qos/traffic-control/
Basic or Advanced Configuration Modes variable. Only at that point will a TC configuration be added
to the current firewall configuration.
On the RX1500 and RX5000, traffic control is not available on the Ethernet traffic on any
line module when when Layer 3 hardware acceleration is enabled. Therefore, it is intended
to be used only on the WAN interfaces.
36.1. Traffic Control Modes
Traffic Control functions are divided into two modes: basic mode and advanced mode. The basic mode
contains functions with basic traffic control configuration parameters. The advanced mode contains
functions with advanced traffic control configuration parameters. The two modes cannot be accessed
simultaneously. Only the mode that is currently configured can be accessed.
36.1.1. Traffic Control Basic (basic-configuration) Configuration Mode
Basic-configuration mode offers a limited set of options and parameters. Use this mode to set the
outgoing bandwidth for an interface, the interface priority (high, medium, low), and some simple traffic
control characteristics. Basic traffic shaping affects traffic identified by protocol, port number, address,
and interface. Note that some of these options are mutually exclusive; refer to the information given
for each option.
In basic-configuration mode, a packet is categorized based on the contents of its TOS field if it does
not match any of the defined bands.
36.1.2. Traffic Control Advanced (advanced-configuration)
Configuration Mode
In advanced-configuration mode, each interface to be managed is assigned a total bandwidth that it
should allow for incoming and outgoing traffic. Classes are then defined for each interface, each with
its own minimum assured bandwidth and a maximum permitted bandwidth. The combined minimum
of the classes on an interface must be no more than the total outbound bandwidth specified for the
interface. Each class is also assigned a priority, and any bandwidth left over after each class has
received its minimum allocation (if needed) will be allocated to the lowest priority class up until it reaches
its maximum bandwidth, after which the next priority is allocated more bandwidth. When the specified
total bandwidth for the interface is reached, no further packets are sent, and any further packets may
be dropped if the interface queues are full.
Packets are assigned to classes on the outbound interface based on either a mark assigned to the
packet, or the ToS (type of service) field in the IP header. If the ToS field matches a defined class,
then the packet is allocated to that class. Otherwise, it is allocated to any class that matches the mark
