IBM eServer 130 xSeries User Reference Manual page 92

IEEE 802.1p is an IEEE standard for tagging, or adding additional bytes of information
to packets with different priority levels. Packets are tagged with 4 additional bytes,
which increase the packet size and indicate a priority level. When you send these
packets out on the network, the higher priority packets are transferred first. Priority
packet tagging (also known as Traffic Class Expediting) enables the adapter to work
with other elements of the network (such as switches and routers) to deliver priority
packets first. You can assign specific priority levels from 0 (low) to 7 (high).
You can assign values to packets based on their priority when you use the IEEE
802.1p standard for packet tagging. This method requires a network infrastructure
that supports packet tagging. The routing devices receiving and transferring these
packets on your network must support 802.1p for tagging to be effective.
After you set up the priority filter in Priority Packet, you must launch IBMSet and select
802.1p/802.1Q Tagging on the Advanced page.
Note: IEEE 802.1p tagging increases the size of the packets it tags. Some hubs and
The requirements for effectively using IEEE 802.1p tagging are:
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If your network infrastructure devices do not support IEEE 802.1p or you are not sure,
you can still define filters and send packets as high priority. While High Priority Queue
(HPQ) does not provide the precise priority levels of 802.1p tagging, it does assign
traffic as either high or low priority and sends high priority packets first. Therefore, if
there are multiple applications on a system sending packets, the packets from the
application with a filter are sent out first. HPQ does not change network routing, nor
does it add any information to the packets.
To assign HPQ, you can specify it using Priority Packet when you create or assign a
filter.
To effectively use HPQ, the adapter cannot be assigned to an adapter team.
Virtual LAN mode: A virtual LAN (VLAN) is a logical grouping of network devices
put together as a LAN, regardless of their physical grouping or collision domains.
Using VLANs increases network performance and improves network security.
VLANs offer you the ability to group users and devices together into logical
workgroups. This can simplify network administration when connecting clients to
appliance servers that are geographically dispersed across the building, campus, or
enterprise network.
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IBM xSeries 130: User's Reference
switches will not recognize the larger packets and will drop them. Check your
hub or switch documentation to see if they support 802.1p. (You can configure
the switch to strip the tags from the packets and send it on to the next
destination as normal traffic). If these devices do not support 802.1p or if you
are not sure, use High Priority Queue (HPQ) to prioritize network traffic.
The other devices receiving and routing 802.1p tagged packets must support
802.1p.
The adapters on these devices must support 802.1p. The Ethernet controller in
your appliance server, all IBM Netfinity 10/100 Ethernet Security Adapters, and
IBM 10/100 Ethernet Server Adapters support 802.1p.
The adapter cannot be assigned to an adapter team.
If you are setting up VLANs and packet tagging on the same adapter,
802.1p/802.1Q Tagging must be enabled on the IBMSet Advanced page.