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Priority Packet utilizes two different methods for accelerating high priority traffic. The Intel-exclusive High Priority Queue feature can be used in any network environment. The 802.1p tagging feature can only be effective in network environments that are 802.1p capable.
As far as 802.1p capability is concerned, interconnecting network hardware can generally be classified into three groups.
- Fully 802.1p compliant. This is hardware that supports the 802.1p tagging feature and will forward packets in accordance with the published specification. If your internetworking hardware falls into this category, then you can use 802.1p tagging to its fullest advantage.
- Compatible, but not 802.1p compliant. This is hardware that will simply forward the tagged packets in the same manner as they do untagged packets. Class I and II repeater type hubs, and some switching hubs, fall into this category. If your internetworking hardware falls into this category, then enabling 802.1p tagging should not cause a network problem, but you will not gain any performance from doing so.
- Not compatible. This is hardware that cannot interpret tagged packets and will not forward them. If your internetworking hardware falls into this category, then tagging should not be enabled.
You may need to consult with the manufacturer of your interconnecting network hardware to determine if it is compatible with the IEEE 802.1p standard.
You should not mix compatible and incompatible systems on the same segment. If a port on an 802.1p compatible switch is connected to an incompatible switch, or a segment containing incompatible hardware or end nodes, then that port should be configured to remove the additional bytes of tagging information before forwarding them.
Other notes concerning Priority Packet applicability
In systems equipped with more than one Intel PRO/100+ adapter, each adapter must have IEEE 802.1p/802.1q tagging enabled separately.
Priority Filters apply to all adapters in a system and cannot be applied individually to adapters in multi-homed systems.
Tagging is currently not supported in conjunction with adapter teaming features (Adapter Fault Tolerance, Adaptive Load Balancing and Intel Fast EtherChannel).
Both 802.1p packet tagging and high priority queuing are not compatible with legacy Intel network adapters based on the 82557 LAN controller chip (PRO/100B and PRO/10+ PCI adapters).
This applies to:
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