Ip Tos / Diffserv - Hirschmann RS20 User Manual

Network Load Control
When using VLAN prioritizing, note the following special features:

End-to-end prioritizing requires the VLAN tags to be transmitted to the
entire network, which means that all network components must be VLAN-
capable.
 Routers cannot receive or send packets with VLAN tags via port-based
router interfaces.
8.4.3

IP ToS / DiffServ

TYPE of Service

The Type of Service (ToS) field in the IP header
part of the IP protocol from the start, and it is used to differentiate various
services in IP networks. Even back then, there were ideas about
differentiated treatment of IP packets, due to the limited bandwidth
available and the unreliable connection paths. Because of the continuous
increase in the available bandwidth, there was no need to use the ToS
field. Only with the real-time requirements of today's networks has the
ToS field become significant again. Selecting the ToS byte of the IP
header enables you to differentiate between different services. However,
this field is not widely used in practice.
Bits 1
0
Precedence
Bits (0-2): IP Precedence Defined Bits (3-6): Type of Service Defined Bit (7)
111 - Network Control
110 - Internetwork Control
101 - CRITIC / ECP
100 - Flash Override
011 - Flash
Table 9: ToS field in the IP header
UM BasicConfig L2E
Release 8.0 05/2013
2 3 4
Type of Service
0000 - [all normal]
1000 - [minimize delay]
0100 - [maximize throughput]
0010 - [maximize reliability]
0001 - [minimize monetary cost]
(see table 9)
5 6 7
MBZ
8.4 QoS/Priority
has been
0 - Must be zero
131