Overview
Introduction
1-5
1.1.9
Flow Control
Flow control is a method of managing the flow of frames between two devices. It ensures that a
transmitting device does not overwhelm a receiving device with data. This is accomplished by the
transmitting device pausing its transmission while the receiving device processes the frames
already received.
The 2H258-17R 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. Flow control can be enabled or disabled on a port-by-port basis.
Back pressure flow control is supported on all Ethernet ports operating in the standard mode of
operation. Flow control can be enabled or disabled on a port-by-port basis.
1.1.10 GARP Switch Operation
Some or all ports on the switch may be activated to operate under the Generic Attribute
Registration Protocol (GARP) applications, GARP VLAN Registration Protocol (GVRP) and/or
GARP Multicast Registration Protocol (GMRP).
GARP is a protocol, or set of rules, that outlines a mechanism for propagating the port state and/or
user information throughout a bridged LAN to keep track of users and VLANs on the network
fabric. MAC bridges and end users alike can take part in the registration and de-registration of
GARP attributes such as VLAN and multicast group membership. For more details on how GVRP
and GMRP handle frames under GARP, and how to configure the switch ports to take advantage of
this operation, refer to the
SmartSwitch Series 2E253, 2H252, 2H253, and 2H258 Local
Management User’s Guide
.
1.1.11 802.1 Port Priority
The 802.1 port priority is used to assign a default priority to the frames received without priority
information in their tag header, map prioritized frames to the appropriate transmit queues, and
prioritize frames according to protocol type. The 802.1 port priority is part of the IEEE 802.1D
standard.
