Glossary
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ICMP
Internet Control Message Protocol: Documented in RFC 792, it is a
network layer Internet protocol for the purpose of reporting errors and pro-
viding information pertinent to IP packet procedures.
IEEE
Institute of Electrical and Electronics Engineers: A professional orga-
nization that, among other activities, defines standards in a number of fields
within computing and electronics, including networking and communica-
tions. IEEE standards are the predominant LAN standards used today
throughout the industry. Many protocols are commonly known by the ref-
erence number of the corresponding IEEE standard.
IEEE 802.1
The IEEE committee specification that defines the bridging
group. The specification for STP (Spanning Tree Protocol) is IEEE 802.1d.
The STP uses SPA (spanning-tree algorithm) to find and prevent network
loops in bridged networks. The specification for VLAN trunking is IEEE
802.1q.
IEEE 802.3
The IEEE committee specification that defines the Ethernet
group, specifically the original 10Mbps standard. Ethernet is a LAN pro-
tocol that specifies physical layer and MAC sublayer media access. IEEE
802.3 uses CSMA/CD to provide access for many devices on the same net-
work. FastEthernet is defined as 802.3u, and Gigabit Ethernet is defined as
802.3q. See also: CSMA/CD.
IEEE 802.5
IEEE committee that defines Token Ring media access.
IGMP
Internet Group Management Protocol: Employed by IP hosts, the
protocol that reports their multicast group memberships to an adjacent mul-
ticast router. The first version, IGMPv1, allows hosts to subscribe to or join
specified multicast groups. Enhancements were made to IGMPv2 to facili-
tate a host-initiated leave process.
IGMP Join process
The process by which hosts may join a multicast ses-
sion outside of the Membership Query interval.
IGMP Leave process
IGMPv1 does not have a formal leave process; a
period of three query intervals must pass with no host confirmation before
the interface is deactivated. IGMPv2 does allow the host to initiate the leave
process immediately.
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