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LANE (LAN Emulation) is a standard defined by the ATM
Forum that gives two stations attached via ATM the same capabilities
they normally have with legacy LANs, such as Ethernet and Token
Ring. As the name suggests, the function of the LANE protocol is to
emulate a LAN on top of an ATM network. Specifically, the LANE
protocol defines mechanisms for emulating either an IEEE 802.3
Ethernet or an 802.5 Token Ring LAN.
The LANE protocol defines a service
interface for higher-layer (that is, network-layer) protocols that
is identical to that of existing LANs. Data sent across the ATM
network is encapsulated in the appropriate LAN MAC format. In other
words, the LANE protocols make an ATM network look and behave like
an Ethernet or Token Ring LAN, albeit one operating much faster than
actual Ethernet or Token Ring LAN networks.
An ELAN (emulated LAN) provides Layer
2 communication between all users on an ELAN. One or more ELANs can
run on the same ATM network. However, each ELAN is independent of
the others and users on separate ELANs cannot communicate directly.
Just like a VLAN, communication between ELANs is possible only
through routers or bridges.
Because an ELAN provides Layer 2
communication, it can be equated to a broadcast domain. VLANs can
also be thought of as broadcast domains. This makes it possible to
map an ELAN to a VLAN on Layer 2 switches with different VLAN
multiplexing technologies such as ISL or 802.10. In addition, IP
subnets and Internetwork Packet Exchange (IPX) networks that are
defined on Layer 3-capable devices such as routers frequently map
into broadcast domains (barring secondary addressing). This makes it
possible to assign an IP subnetwork or an IP network to an ELAN.
It is important to note that LANE
does not attempt to emulate the access method of the specific LAN
concerned (that is, carrier sense multiple access collision detect [CSMA/CD]
for Ethernet or token passing for IEEE 802.5). LANE requires no
modifications to higher-layer protocols to enable their operation
over an ATM network. Because the LANE service presents the same
service interface of existing MAC protocols to network-layer drivers
(such as a network driver interface specification [NDIS] or Open
Data-Link Interface [ODI] like driver interface), no changes are
required for these drivers.
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