C H A P T E R 2 | Intel® NetStructure™ 470T and 470F Switches User Guide |
Note
Dynamically created VLANs are not saved in the switch’s memory. If the device sending out the GVRP updates is removed, the dynamic VLAN is removed.
GARP (Generic Attribute Registration Protocol) is defined by the IEEE 802.1D (1998 Edition) specification and is the mechanism used by switches and end nodes (servers, PCs, and so on) to propagate configuration across the network domain. GVRP uses GARP as a foundation to propagate VLAN configuration to other switches. Devices that support GVRP transmit their updates to a known multicast address that all
Sending GVRP messages between switches accomplishes the following tasks:
•Dynamically adds or removes a port from participating in a VLAN
•Sends updates about the switch’s own VLAN configuration to neighboring
•Integrates dynamic and static VLAN configurations within the same switch. For devices that don’t support GVRP, static VLAN configurations are created by the user on the switch.
When the switch is running 802.1Q VLANs, Spanning Tree Protocol is enabled for GVRP to work properly.
Internet Group Management Protocol (IGMP)
Normally, multicast traffic is broadcast by the switch to all ports. For multicast traffic based on TCP/IP using the IGMP protocol, the switch can optimize the broadcasting of multicast traffic by forwarding multicast traffic only to ports that require it.
IGMP Snooping is a feature that allows the switch to forward multicast traffic intelligently. The switch “snoops” the IGMP query and report messages and forwards traffic only to the ports that request the multicast traffic. This prevents the switch from broadcasting the traffic to all ports and possibly affecting network performance.
IGMP Snooping requires a router that detects multicast groups on its subnets and keeps track of group membership.
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