Packet Marking - HP ProCurve Secure Router 7203 dl Advanced Management And Configuration Manual

Setting Up Quality of Service
Configuring WFQ
7-16
Now, consider an interface that handles more conversations at once—for
example, 100 routine subqueues, 5 subqueues with a precedence of 3, and 2
queues for VoIP traffic with a precedence of 5. Even though VoIP traffic
receives relatively more bandwidth than any individual routine subqueue,
routine traffic altogether consumes 75 percent of the bandwidth. Neither VoIP
queue is guaranteed even 5 percent of the total bandwidth. (See Table 7-4.) In
addition, even though some subqueues receive relatively more bandwidth, all
traffic must wait in queues. This level of service is inadequate for real-time
traffic such as VoIP, which requires low latency and jitter.
Table 7-4. WFQ Example 2
Subqueue Precedence
1 0
2 0
...100 0
101 3
...105 3
106 5
107 5
Total —

Packet Marking

WFQ allocates bandwidth to conversation subqueues according to the IP
precedence value in the IP headers of packets in the subqueue. The higher the
value, the greater the bandwidth the queue is given. In order for WFQ to
function, therefore, packets must somehow be marked with this value.
Packets can be marked:
by an application or other device outside the router (typically, packet
marking is most effective when it is implemented near the edge)
by the ProCurve Secure Router
The router can also recognize DiffServ values, but it does not grant differen-
tiated service for each DiffServ value. Instead, it maps several DiffServ values
to a single IP precedence value and then treats the traffic as if it were marked
with that value. (See Table 7-5.)
Precedence + 1
1
1
1
4
4
6
6
132
Weight
.0076
.0076
.0076
.030
.030
.045
.045
1