Moxa Technologies EDS-405A User Manual

 

[Eq. 4]:  2 * (Hello Time + 1 sec)  ≦ Max. Age ≦  2 * (Forwarding Delay – 1 sec) 

The EDS’s firmware will alert you immediately if any of these restrictions are violated. For 
example, setting 

Hello Time = 5 sec, Max. Age = 20 sec, and Forwarding Delay = 4 sec does not violate Eqs. 1 
through 3, but does violate Eq. 4, since in this case, 

2 * (Hello Time + 1 sec) = 12 sec, and 2 * (Forwarding Delay – 1 sec) = 6 sec. 

You can remedy the situation in a multitude of ways. One solution is simply to increase the 
Forwarding Delay to at least 11 sec. 

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. 

EThe DS’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. The EDS 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. The EDS’s QoS capability improves the performance and 
determinism of industrial networks for mission critical applications. 

The Traffic Prioritization Concept 

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: 

y 

Improve network performance by controlling a wide variety of traffic and managing 

congestion. 

y 

Assign priorities to different categories of traffic. For example, set higher priorities for 

time-critical or business-critical applications. 

y 

Provide predictable throughput for multimedia applications, such as video conferencing or 

voice over IP, and minimize traffic delay and jitter. 

y 

Improve network performance as the amount of traffic grows. This will save cost by reducing 

the need to keep adding bandwidth to the network. 

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. 

The EDS traffic prioritization depends on two industry-standard methods: