Upper Layer Protocols
The Upper Layer is the layer in the network architecture that relates to user applications and service requests. For example, an application could be file transfer software, and the service request could be a request to transfer a file from a user’s PC to a shared file server.
User data and control information is passed down the network layers in the source device, and passed up the layers at the destination device.
What is LAN Emulation (LANE)?
LAN Emulation (LANE) allows users on Ethernet, Token Ring, and other traditional LAN networks, to communicate with each other over an ATM network.
LANE emulates the broadcast nature of traditional LANs. Each LANE broadcast domain is known as an Emulated LAN (ELAN).
Each ELAN can only carry one type of traffic. For example, an ELAN could carry either Ethernet frames or Token Ring frames, but not both.
There can be several ELANs on a single ATM network. Some of these ELANs could be carrying Ethernet traffic and others could be carrying Token Ring traffic.
Traffic from one ELAN is not seen on another ELAN, as they are logically separate broadcast domains. If devices from different ELANs need to communicate with each other, they must do so using an ATM router.
LAN emulation software is contained within ATM devices which can be added to your existing network.
LANE allows you to add ATM to your network without having to replace or upgrade the whole of your underlying technology. LANE allows you to do this because it is completely transparent to the ATM network and to the traditional LAN network,
LAN Emulation allows users on traditional LANs to communicate over ATM by performing the following tasks:
■Emulates the broadcast nature of LANs.
■Maps MAC addresses to ATM addresses.
■Maps upper layer
Although LAN Emulation emulates a range of network technologies, all examples in this guide are be based on an Ethernet network.
