Extreme Networks ExtremeWare XOS Guide Manual page 297

at each switch location. Another advantage is that endstations can perform their own packet marking
on an application-specific basis. Extreme Networks switch products have the capability of observing
and manipulating packet marking information with no performance penalty.
The documented capabilities for 802.1p priority markings or DiffServ capabilities (if supported) are not
impacted by the switching or routing configuration of the switch. For example, 802.1p information can
be preserved across a routed switch boundary and DiffServ code points can be observed or overwritten
across a Layer 2 switch boundary.
This section covers the following topics:
Configuring 802.1p priority
●
Configuring DiffServ
●
Configuring 802.1p Priority
Extreme Networks switches support the standard IEEE 802.1p priority bits that are part of a tagged
Ethernet packet. The 802.1p bits can be used to prioritize the packet and to assign that packet to a
particular QoS profile.
When a tagged packet arrives at the switch, the switch examines the 802.1p priority field and maps the
packet to a specific queue when subsequently transmitting the packet. The 802.1p priority field is
located directly following the 802.1Q type field and preceding the 802.1Q VLAN ID, as shown in
Figure 14.
Figure 14: Ethernet packet encapsulation
802.1Q
type
8100
Destination Source
address address
This section covers the following topics:
802.1p information on the BlackDiamond 10K only
●
Observing the 802.1p information
●
Changing the default 802.1p mapping
●
Replacing 802.1p information
●
ExtremeWare XOS 11.3 Concepts Guide
802.1p
priority
IP packet
802.1Q
VLAN ID
CRC
Traffic Groupings
EW_024
297