Lancom ES-2126+ Manual page 121

LANCOM ES-2126+ and LANCOM ES-2126P+
Chapter 4: Operation of Web- based Management
bit SERVICE TYPE field that specifies how the datagram should be handled.
The field could be divided into six subfields as follows, PRECEDENCE (3 bits),
D-Type (Delay Priority, 1 bit ), T-Type (Throughput Priority, 1bit), R-Type (Reli-
ability Priority, 1bit ), M-Type (Monetary Cost Priority, 1bit ), and UNUSED (1bit
).
User can randomly control these fields to achieve some special QoS goals.
When bits D, T, R, or M set, the D bit requests low delay, the T bit requests high
throughput, the R bit requests high reliability, and the M bit requests low cost.
DiffServ DSCP Priority act on DSCP field of IP Header. In the late 1990s, the
IETF redefined the meaning of the 8-bit SERVICE TYPE field to accommodate
a set of differentiated services (DS). Under the differentiated services interpre-
tation, the first six bits comprise a codepoint, which is sometimes abbreviated
DSCP, and the last two bits are left unused.
High Priority Packet streams will experience less delay into the switch. For
handing different priority packets, each egress port has designed up to 4
queues. Each QoS is influenced by two scheduling, WRR (Weighted Round
Robin) and Strict Priority as well. When you finish to set the priority mapping
to the queue, WRR scheduling will distribute the bandwidth according to the
weight you set for 4 queues (queue 0 to queue 3). Another scheduling is Strict
Priority dedicated for the function named VIP Port of QoS. While we select
some ports as the VIP Port, these ports will own the highest transmitting pri-
ority in egress queue of the switch.
The QoS functions as we mentioned above are able to enabled at the same
time. But, the following precedence will decide whether these functions work
or not.
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enable both VIP and TOS
Choose priorities of VIP and TOS.