Cabletron Systems 9F125-0, 9F120-08, 9F122-12 manual 802.1p Port Priority

Introduction

device, and to have it pause its transmission while the receiving device processes the frames already received. Flow control can be enabled or disabled on a port-by- port basis. Both devices must support the IEEE 802.3x standard for flow control to work.

The 9E531-24 supports the following two types of flow control:

•frame based 802.3x

•back pressure

Frame based 802.3x flow control is supported on all Ethernet ports operating in the full duplex mode.

Back pressure flow control is supported on all Ethernet ports operating in the standard mode of operation.

802.1p Port Priority

The IEEE 802.1p standard is used to assign a default priority to the frames received without priority information in their tag header, and to map prioritized frames to the appropriate transmit queues.

The default priority-to-queue mappings are shown in Table 1-1.This configuration can be changed by the administrator.

Table 1-1. Priority Queuing Configuration

Priority Indicator	Transmit Queue
7	3
6	3
5	2
4	2
3	1
2	0
1	0
0	1

Switching Options

The 9E531-24 provides IEEE Standard-based 802.1 switching or SecureFast Switching Virtual Network Services. In the 802.1 mode (the default mode of operation), the switch functions as an 802.1D switch. When VLANs are configured, it operates as an 802.1Q switch.

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