Garp Switch Operation; Flow Control; 802.1 Port Priority - Cabletron Systems SmartSwitch 6000 Installation & User Manual

Overview

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 6H202, 6H203, 6H252, 6H253, 6H258, 6H259,
6H262, 6E233, and 6E253 Local Management User's Guide.

1.1.11 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 enables the receiving
device to communicate with the transmitting device, and to have it pause its transmission while the
receiving device processes the frames already received. Both devices must support the
IEEE 802.3x standard for flow control to work.
The SmartSwitches support 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.

1.1.12 802.1 Port Priority

IEEE 802.1 port priority is incorporated in the IEEE 802.1D standard. It is used to assign a default
priority to the frames received without priority information in their tag header, to map prioritized
frames to the appropriate transmit queues, and to prioritize frames according to protocol type.
1-6 Introduction