RuggedCom RuggedRouter RX1100 - Manual (Page 196)

20. Traffic Prioritization
Revision 1.14.3 196 RX1000/RX1100™
20. Traffic Prioritization
20.1. Introduction
This chapter familiarizes the user with:
• Enabling/Disabling Traffic Prioritization
• Viewing Traffic Prioritization Statistics
Note
Traffic Prioritization has been retained in ROX for compatibility with older installations that may
rely on it. For new configurations, please use the newer and more flexible
Traffic Control facility
instead.
20.1.1. Traffic Prioritization Fundamentals
The RuggedRouter is able to prioritize traffic transmitted on network interfaces (including Ethernet,
T1E1, DSL and PPP ports), giving preferential treatment to certain classes of traffic.
It is important to note that prioritization can only be applied to outbound traffic. Inbound traffic can
not be prioritized.
The two key elements of prioritization are traffic queues and filters. Each prioritized interface has its
own unique set of these elements.
Note
Traffic Prioritization works most effectively with WAN interfaces. For LAN interfaces please use
the
Traffic Control interface.
20.1.1.1. Priority Queues
Prioritization establishes a number of queues, each holding packets of differing priority. When the
interface is ready to transmit a packet it selects a packet from the highest priority queue first.
If the interface is busy transmitting when packets arrive, they are enqueued in the appropriate queue.
If the interface is not transmitting when the frame arrives to be enqueued, the frame is immediately
transmitted. Prioritization will not add additional delay to a stream of packets of differing priority.
Prioritization will simply reorder the sequence of transmission of packets to send higher priority
packets first.
Note that it is possible in indefinitely stall the transmission of packets from a lower priority queue if a
traffic from a higher queue saturates the interface.
Note
The router mandates that you must have at least a low, normal and high priority queue.
Additionally, the high queue must be of higher priority than the normal queue, which must be of
higher priority than the low queue.