Operation Instructions | EoC 20-01 | Ethernet over Coax | Master
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2021-03-17 | Technical improvements, changes in design, printing- and other errors reserved.
4. Advanced Features
This chapter describes the advanced features offered by your bridge. And they are applicable to all NMU,
Master and connected EP.
4.1. QoS
Quality of Service is enforced by assigning each incoming packet with a predefined priority value. Packet with
higher priority should be processed as soon as possible (fast forwarding). In shortage of buffers, some low
priority packets should be discarded to smooth the high priority traffic flow. Higher priority traffic will have
higher data rate and lower possibility of being discarded.
The numbering priority value ranges from 0 to 7, and 7 represents the highest priority level. EOC 20-01/EoC 20-
02 supports priority scheme as 802.1p, IP TOS/TC or DSCP, and TCP/UDP protocol. There are 4 priority queues
for packet. Packet with priority value 0 or 1 goes to the same queue, denoted as Queue0. Queue1 has priority
value 2 and 3, Queue2 has priority value 4 and 5, and Queue3 has priority value 6 and 7. Totally 4 levels of
service are provided. Queue3 need to have higher “Service Weight”, i.e. packets reside in Queue3 will be send
out faster. Packets in Queue0 are classified as less important.
4.2. Queue Scheduling
Decide how fast the packets in different queues are forwarded.
4.2.1. Strict Priority (SP) – default mode
Always transmit packets in higher priority queue first. Packets in lower priority will be forwarded after the
higher priority queue gets empty.
4.2.2. Weighted Fair Queue (WFQ)
Service weight for Q3/Q2/Q1/Q0 is fixed to 8/4//2/1.That is, forward 8 packets in Q3, then 4 packets in Q2, then
2 packets in Q1, then 1 packet in Q0. And repeat the sequence.
4.2.3. Mixed (SP & WFQ)
Transmit packets in Q3 first alike Strict Priority, packets in Q2/Q1/Q0 follows fixed service weight 4/2/1 as
WFQ.
4.3. TCP/UDP Port Number – default is empty
Different TCP or UDP port number usually states for different protocol. You may raise the priority for important
application with specified TCP or UDP port number. In EOC 20-01/EoC 20-02 you can assign higher priority for
total 3 different TCP/UDP protocols.
4.4. 802.1p – default scheme
Tagged packet has the 3-bit (value 0~7) 802.1p field for priority mapping. The default priority mapping scheme
-- to map 802.1p value 7 to priority 7, to map value 0 to priority 0, and so on. It takes effect in both
downstream and upstream.
