EOTec 2104 User Manual
Introducing Switch Tools
Switch Configuration Window – Port Priorities Page
Choosing a Forwarding Policy
Choose the forwarding policy that is more appropriate for your application:
•
The first policy states that the Weed Ring Switch will
send high-priority frames
before all others.
Under this policy, all data in the highest port priority queue is
sent before sending data from the second-highest port priority queue. All data
from the second-highest port priority queue is sent before sending data from the
third highest, and so on. This assures that high-priority data always gets through
as quickly as possible.
•
The second policy states that the Weed Ring Switch will
allow lower priority
frames through, a few at a time
. Under this policy, a round-robin algorithm is
used, weighted so that more high-priority than low-priority data gets through.
Specifically, the switch sends eight frames from the urgent port priority queue,
followed by four from the expedited port priority queue, two from the normal port
priority queue, and one from the background port priority queue, and then starts
over with the urgent queue. This assures that the lower-priority queues will not be
starved.
Adding Priority to Messages
If any devices connected to the EOTec 2104 Ring Switch do not natively put priority-
handling information into their messages, you still can prioritize their messages by
adding 802.1 CoS (Class of Service) priority tags.
Note
: When adding priority data to non-prioritized messages, the switch can only add
CoS tags—it will not modify the IP ToS (Type of Service) header. All messages
with a certain priority in the IP ToS header will always enter and leave the Weed
Ring Switch with the same value. The IP ToS header priority is usually set at the
source device (device from which the IP packet originated).
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