Network Load Control
144
8.4
QoS/Priority
Basic Configuration
Release
6.0
07/2010
When using VLAN prioritizing, note the following special features:
X 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.
X 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 (see table 13) has been
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
0
1324567
MBZPrecedence Type of Service
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