TCP/IP Tutorial and Technical Overview - IBM Redbooks

first router in the source domain that supports traffic conditioning. Figure 8-19
shows the initial marking of a packet inside of a host and a router.
Classifier
Marker
Host Host
Application
TCP
IP
DS
Byte
Router
TCP
Data
Figure 8-19 Initial marking of data packets
IP
Data
Initial marking in the host
TCP Data
Classifier
Marker
Application
TCP Data
In our example, the DS network has the policy that the packets from the audio
application should have higher priority than other packets. The sender host can
mark the DS field of all outgoing packets with a DS codepoint that indicates
higher priority. Alternatively, the first-hop router directly connected to the
sender's host can classify the traffic and mark the packets with the correct DS
codepoint. The source DS domain is responsible for ensuring that the
aggregated traffic toward its provider DS domain conforms to the SLA between
client and service provider. The boundary node of the source domain should also
monitor that the provided service conforms to the requested service and can
police, shape, or re-mark packets as necessary.
Integrated Services (Intserv) over Diffserv networks
The basic idea is to use both architectures to provide an end-to-end, quantitative
QoS, which will also allow scalability. This will be achieved by applying the
TCP
IP
IP
DS
Byte
Router
Data
TCP Data
IP
Initial marking in the router
TCP Data
Chapter 8. Quality of service 319