EDS-408A/405A Series User’s Manual

Featured Functions

HINT: Take the following steps to avoid guessing:

Step 1: Assign a value to Hello Time and then calculate the left most part of Eq. 4 to get the lower limit of Max. Age.

Step 2: Assign a value to Forwarding Delay and then calculate the right most part of Eq. 4 to get the upper limit for Max. Age.

Step 3: Assign a value to Forwarding Delay that satisfies the conditions in Eq. 3 and Eq. 4.

Using Traffic Prioritization

EDS’s traffic prioritization capability provides Quality of Service (QoS) to your network by making data delivery more reliable. You can prioritize traffic on your network to ensure that high priority data is transmitted with minimum delay. Traffic can be controlled by a set of rules to obtain the required Quality of Service for your network. The rules define different types of traffic and specify how each type should be treated as it passes through the switch. MOXA EtherDevice Switch can inspect both IEEE 802.1p/1Q layer 2 QoS tags, and even layer 3 TOS information to provide consistent classification of the entire network. EDS’s QoS capability improves the performance and determinism of industrial networks for mission critical applications.

The Traffic Prioritization Concept

What is Traffic Prioritization?

Traffic prioritization allows you to prioritize data so that time-sensitive and system-critical data can be transferred smoothly and with minimal delay over a network. The benefits of using traffic prioritization are:

yImprove network performance by controlling a wide variety of traffic and managing congestion.

yAssign priorities to different categories of traffic. For example, set higher priorities for time-critical or business-critical applications.

yProvide predictable throughput for multimedia applications, such as video conferencing or voice over IP, and minimize traffic delay and jitter.

yImprove network performance as the amount of traffic grows. This will save cost by reducing the need to keep adding bandwidth to the network.

How Traffic Prioritization Works

Traffic prioritization uses the four traffic queues that are present in your EDS to ensure that high priority traffic is forwarded on a different queue from lower priority traffic. This is what provides Quality of Service (QoS) to your network.

EDS traffic prioritization depends on two industry-standard methods:

yIEEE 802.1D—a layer 2 marking scheme.

yDifferentiated Services (DiffServ)—a layer 3 marking scheme.IEEE 802.1D Traffic Marking

The IEEE Std 802.1D, 1998 Edition marking scheme, which is an enhancement to IEEE Std 802.1D, enables Quality of Service on the LAN. Traffic service levels are defined in the IEEE 802.1Q 4-byte tag, which is used to carry VLAN identification as well as IEEE 802.1p priority information. The 4-byte tag immediately follows the destination MAC address and Source MAC address.

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