HP 2610, Руководство по продвинутому управлению трафиком

Страница: 226 / 364

Quality of Service (QoS): Managing Bandwidth More Effectively
Using QoS Classifiers To Configure QoS for Outbound Traffic
To replace this option with the ToS diff-services option, just configure
diff­
services as described below, which automatically disables IP-Precedence. To
disable IP-Precedence without enabling the diff-services option, use this
command:
ProCurve(config)# no qos type-of-service
Assigning an 802.1p Priority to IPv4 Packets on the Basis
of Incoming DSCP
One of the best uses for this option is on an interior switch where you want
to honor (continue) a policy set on an edge switch. That is, it enables you to
select incoming packets having a specific DSCP and forward these packets
with the desired 802.1p priority. For example, if an edge switch “A” marks all
packets received on port A5 with a particular DSCP, you can configure a
downstream (interior) switch “B” to handle such packets with the desired
priority (regardless of whether 802.1Q tagged VLANs are in use).
LAN
A5
Edge
Switch
“A”
LAN
Interior
Switch
“B”
Work-
Group
Work-
Group
Marked Traffic from port A5 on Edge Switch “A”
Other Traffic
Figure 6-15. Interior Switch “B” Honors the Policy Established in Edge Switch “A”
To do so, assign the desired 802.1p priority to the same codepoint that the
upstream or edge switch assigns to the selected packets. When the
downstream switch receives an IPv4 packet carrying one of these codepoints,
it assigns the configured priority to the packet and sends it out the appropriate
priority queue. (The packet retains the codepoint it received from the
upstream or edge switch). You can use this option concurrently with the
diffserv DSCP Policy option (described later in this section), as long as the
DSCPs specified in the two options do not match.
6-36