Cabletron Systems 9E531-24 - Manual (Page 17)

1-5
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.
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.
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