LevelOne GES-2451 - Manual (Page 127)

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Internet Group Management Protocol (IGMP)
A protocol through which hosts can register with their local router for multicast services. If there is
more than one multicast switch/router on a given subnetwork, one of the devices is made the
“querier” and assumes responsibility for keeping track of group membership.
IGMP Snooping
Listening to IGMP Query and IGMP Report packets transferred between IP Multicast Routers and
IP Multicast host groups to identify IP Multicast group members.
IGMP Query
On each subnetwork, one IGMP-capable device will act as the querier — that is, the device that
asks all hosts to report on the IP multicast groups they wish to join or to which they already belong.
The elected querier will be the device with the lowest IP address in the subnetwork.
IP Multicast Filtering
It is a feature to allow or deny the Client to add the specified multicast group.
Multicast Switching
A process whereby the switch filters incoming multicast frames for services which no attached
host has registered, or forwards them to all ports contained within the designated multicast group.
Layer 2
Data Link layer in the ISO 7-Layer Data Communications Protocol. This is related directly to the
hardware interface for network devices and passes on traffic based on MAC addresses.
Link Aggregation
See Port Trunk.
Management Information Base (MIB)
An acronym for Management Information Base. It is a set of database objects that contains
information about a specific device.
MD5 Message-Digest Algorithm
An algorithm that is used to create digital signatures. It is intended for use with 32 bit machines
and is safer than the MD4 algorithm, which has been broken. MD5 is a one-way hash function,
meaning that it takes a message and converts it into a fixed string of digits, also called a message
digest.
Network Time Protocol (NTP)
NTP provides the mechanisms to synchronize time across the network. The time servers operate
in a hierarchical-master-slave configuration in order to synchronize local clocks within the subnet
and to national time standards via wire or radio.
Port Mirroring
A method whereby data on a target port is mirrored to a monitor port for troubleshooting with a
logic analyzer or RMON probe. This allows data on the target port to be studied unobstructively.
Port Trunk
Defines a network link aggregation and trunking method which specifies how to create a single
high-speed logical link that combines several lower-speed physical links.