## Intel® Priority Packet Overview

Intel® Priority Packet is a utility that lets you set up priority filters to process high priority network traffic before normal traffic. Using Priority Packet, you set up priority filters to give priority to time-critical traffic. This is also known as Traffic Class Expediting. You can set up global filters that apply to the entire system or network-component-specific filters that apply only to specific network components (individual adapters or VLANs). You can also create custom priority filters or use priority filter templates to assign filter properties you use often. Priority Packet comes with pre-defined priority filter templates or you can create your own templates.

Use Priority Packet filters for these reasons:

- To tag packets with priority levels or forwarding behaviors.

- To drop incoming packets that match certain criteria.

- To count the number of packets that match certain criteria.

Priority Packet is available on the Product CD. To install or run Priority Packet, you must have administrative rights.

To use Priority Packet with Microsoft* Windows* 98 or Windows Me, you must first enable remote DCOM connectivity on your system. For more information, visit the Microsoft web site at: http://www.microsoft.com/com/tech/dcom.asp

#### Prioritizing Network Traffic

Intel's Priority Packet lets you set up priority filters to send packets on the network with an indicated priority or forwarding behavior. By prioritizing traffic at the hosts or entry point of the network, network devices can base forwarding decisions on priority information defined in the packet.

Priority filters are parameters you assign to packets. Using Priority Filter Wizard, you set up filters from templates or define custom priority filters based on the following traffic filter types:

- Node (MAC) address

- Ethertype

- TCP/IP information

- IPX information

Priority Packet provides the following methods for prioritizing traffic:

- IEEE 802.1p Tagging

- IP ToS (Type of Service) Layer 3 Tagging—supporting both Differentiated Services Codepoint (DSCP) and Legacy IP Precedence

- Intel High Priority Queue

#### IEEE 802.1p Tagging

802.1p is an IEEE standard for adding additional bytes of information, also called tagging, to packets with different priority levels utilizing four additional bytes in the header. When these packets are sent out on the network, the higher priority packets are transferred first by 802.1p-aware devices. To effectively use 802.1p tagging, the other devices receiving and routing 802.1p tagged packets must support 802.1p. 802.1p tagging lets you assign specific priority levels from 0 (low) to 7 (high).

| CAUTION: 802.1p tagging increases the size of the packets. Some hubs and switches do not recognize the larger packets, and will drop them because they exceed the maximum frame size of standard Ethernet packets. Check your hub or switch documentation to see if it supports 802.1p. If you are using Intel® PRO/100 adapters and these routing devices do not support 802.1p, or you are unsure, use High Priority Queue to prioritize network traffic.

You can configure a switch to strip the tags from packets and send them on to the next destination as normal traffic.

You can specify 802.1p tagging using Priority Packet, or when you create or assign a priority filter via Microsoft* Windows* 2000, Windows XP, or Windows Server* 2003.

#### IP ToS Layer 3 Tagging

Priority Packet supports two Type of Service (ToS) tagging methods:

- Differentiated Services Codepoint (DSCP)

- Legacy IP Precedence

Differentiated Services Codepoint (DSCP) is a new tagging method that classifies packets based on network policies and rules, not on priority. The tags assign one of 64 possible forwarding behaviors known as per hop behaviors (PHBs). A PHB provides a particular service level (bandwidth, queuing, and dropping decisions) in accordance with network policy. Using Priority Packet, DSCP tagging lets you assign assured forwarding codepoints, using one of four classes and one of three drop precedence values. You may also enter your own non-standard codepoints.

DSCP tags replace the existing IP header, and do not add any additional bytes to packets. DSCP tags are backwards compatible with legacy ToS IP precedence bits, so non-DSCP compliant, ToS-enabled devices do not conflict with the DSCP mapping. A default DSCP mapping to "best effort" forwarding is applied if network rules are not defined or the devices are non-DSCP compliant.

To assign DSCP, you can specify it using Priority Packet when you create or assign a priority filter for IP traffic.

For more information on DSCP, see RFC 2474 and 2475 on the IETF (Internet Engineering Task Force) Web site.

Legacy IP Precedence is an early tagging method that classifies and prioritizes packets. When these packets are sent out on the network, the higher priority packets are transferred first. Using Priority Packet, Legacy IP Precedence tagging lets you assign the following specific priority levels:

> Network Control = 111 (7 in binary)
> Internet Control = 110 (6 in binary)
> CRITIC/ECP = 101 (5 in binary)
> Flash Override = 100 (4 in binary)
> Flash = 011 (3 in binary)
> Immediate = 010 (2 in binary)
> Priority = 001 (1 in binary)
> Routine = 000 (0 in binary)

To assign a Legacy IP Precedence, you can specify it using Priority Packet when you create or assign a priority filter.

Intel High Priority Queue

If your network infrastructure devices do not support IEEE 802.1p or IP ToS, or you are unsure if either is supported, you can still define priority filters and transmit packets from the adapter onto the network as high priority. While High Priority Queue (HPQ) does not provide the precise priority levels of 802.1p and IP ToS 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 priority 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 priority filter.

If you add an adapter to a team, its filters are removed automatically. When you apply HPQ tagging to a team, you assign HPQ tagging to all adapters in the same team, including any new ones subsequently added.

### Dropping Incoming Packets

You can use Priority Packet to specify that incoming packets of a certain type should be dropped.

### Counting Incoming or Outgoing Packets

You can use Priority Packet to specify that you want all incoming or outgoing packets of a certain type to be counted. This allows you to monitor and track specific types of packets.

## Supported Adapters

The following Intel adapters support Priority Packet :

- All Intel PRO/100 server and desktop adapters based on the 82558 Media Access Controller (MAC) and newer (e.g., Intel PRO/100+, PRO/100 S, and PRO/100 Cardbus II adapters).

- All Intel® PRO/1000 server and desktop adapters based on the 82544 Media Access Controller (MAC) and newer (e.g., Intel PRO/1000 family of adapters).

| NOTES: Not all features are compatible with all adapters. Depending on your adapter, some features may be disabled. Priority Packet only supports Intel adapters. You cannot set filters for non-Intel adapters.

See the support website for details.

`Last modified on 1/31/05 2:43p Revision 2`