Glossary H

G

Gigabit EtherChannel

See: Fast EtherChannel.

Gigabit Ethernet

1000Mbps version of the IEEE 802.3. FastEthernet offers a speed increase of 10 times that of the 10BaseT Ethernet specification while preserving qualities such as frame format, MAC, mechanisms, and MTU.

GLBP

Gateway Load Balancing Protocol: A protocol designed to provide redundancy of the client default gateway by using virtual addresses. In addition, the use of virtual MAC addresses allows all routers in a group to forward data. An alternative to HSRP. See also: AVF, AVG, and HSRP.

GNS

Get Nearest Server: On an IPX network, a request packet sent by a customer for determining the location of the nearest active server of a given type. An IPX network client launches a GNS request to get either a direct answer from a connected server or a response from a router disclosing the location of the service on the internetwork to the GNS. GNS is part of IPX and SAP. See also: IPX and SAP.

grafting

A process that activates an interface that has been deactivated by the pruning process. It is initiated by an IGMP membership report sent to the router.

GRE

Generic Routing Encapsulation: A tunneling protocol created by Cisco with the capacity for encapsulating a wide variety of protocol packet types inside IP tunnels, thereby generating a virtual point-to-point connection to Cisco routers across an IP network at remote points. IP tunneling using GRE permits network expansion across a single-protocol backbone environment by linking multiprotocol subnetworks in a single-protocol backbone environment.

guard band

The unused frequency area found between two communications channels, furnishing the space necessary to avoid interference between the two.