WAGO-ETHERNET-Zubehör 852
Enhanced Features
53
852-1305 8/4-Port 100BASE-T/1000BASE-SX/LX
Manual
1.1.0
Priority Levels
PCP (“
P
riority
C
ode
P
oint”):
Table 17: Priority Levels
PCP
Network Priority
Traffic Characteristics
1
0 (lowest)
“Background”
0
1
“Best Effort”
2
2
“Excellent Effort”
3
3
“Critical Applications”
4
4
Video, < 100 ms latency
5
5
Video, < 10 ms latency
6
6
Internetwork Control
7
7 (highest)
Network Control
DiffServ (DSCP)
DiffServ (“
Diff
erentiated
Serv
ices”) is a computer networking architecture that
specifies a simple, scalable and coarse-grained mechanism, managing network
traffic and providing (“
Q
uality
o
f
S
ervice”) guarantees in modern IP networks.
DiffServ can, for example, be used to provide low-latency, guaranteed service
(“
G
uaranteed
S
ervice”) to critical network traffic such as voice or video data
while providing simple “Best Effort” traffic guarantees to non-critical services
such as web traffic or file transfers.
DSCP (“
D
ifferentiated
S
ervices
C
ode
P
oint”) is a 6-bit field in the header of IP
packets for packet classification purposes. DSCP replaces the outdated IP
precedence, a 3-bit field in the “Type of Service” byte of the IP header originally
used to classify and prioritize types of traffic.
When using the DiffServ priority mechanism, a packet is classified based on the
DSCP field in the IP header. If the tag is present, the packet is assigned to a
programmable “Egress Queue” based on the value of the “Tagged Priority”. The
“Tagged Priority” can be designated to any available “Queue”.
Version
IHL
Type of Service
Total Length
Marking
Flags
Fragment Offset
Time to Live
Protocol
Header Checksum
Source Address
Destination Address
Options
Padding
Example Internet Data Packet Header
“Type of Service” in the IP header: 8-bit
The “Type of Service” field provides an indication of the abstract parameters of
the “Quality of Service” desired. These parameters are to be used to guide the
