ATM LAN Emulation (LANE) Trebea-Corda Cristian Technical University, Cluj-Napoca

LAN Emulation (LANE) What is LAN Emulation “…makes an ATM interface look like one or more LAN interfaces” (CISCO LANE Overview) Specified in LAN Emulation over ATM (ATM_FORUM ) Approved in Feb 1995, as LE V 1.0 The reason and goals of LANE Interconnectivity and transparency

Types of LANE connectivity All ATM connections LAN to ATM connections LAN to LAN connections (with ATM backbone)

LAN emulated characteristics Connectionless Service Multicast addresses Multicast MAC MAC driver interfaces in ATM stations Emulated LANs Interconnection With Existing LANs

Architecture of LANE

Components of LANE LAN Emulation client software Controlls an ATM interface LAN Emulation Service Three servers Emulated LANs Ethernet/IEEE Token Ring/IEEE 802.5

LANE Clients Role Ethernet/Token Ring frames to AAL5 Uses Virtual Channel Connections (VCC) MAC for each ATM interface

LANE Client Protocol Elements Transmitted frames (with AAL5 frames) Ethernet II (DIX) IEEE 802.2/IEEE Ethernet Token Ring

LANE Service Handles multiple LECs LUNI (LANE User Network Interface) Three components LAN Emulation Configuration Service (LECS) LAN Emulation Server (LES) Broadcast/Unknown Server (BUS)

LANE Client Initialization Connect to LECS ILMI Anycast address reserved for LECS Use a special PVC, with VPI/VCI 0/17 Interact with LECS Send ATM and MAC address, LAN type and supported frame size Receive LES address, LAN type and frame size to be used

LANE Client Initialization Communication with LES Point-to-point connection (Control Direct VCC) JOIN REQUEST control frame JOIN RESPONSE control frame Connection is maintained in point-to- multipoint list

LANE Client Initialization Communication with LES JOIN REQUEST Client ATM and MAC addresses Type of LAN and maximum frame size to be supported Indication if the client acts as proxy for remote MACs (it is switch or edge device) The name of ELAN wished to join (if known)

LANE Client Initialization Communication with LES JOIN RESPONSE Similar fields with JOIN REQUEST Mandatory fields Type of LAN Maximum frame size Name of ELAN Assigns a LANE Client ID (LECID)

Connecting to the BUS LEC requests to the LES the ATM broadcast address for all 1’s MAC address The reply is the BUS address

Address Resolution A LANE Client needs to know either The peer LANE Client ATM address The proxy edge device ATM address Steps of communication LE-ARP request to LES The LES either forwards or responds with the address The connection is opened

Quick Sends and Flushing An alternative to LE-ARP is BUS After broadcast, new connection can be opened LE_FLUSH_REQUEST, path clear request LE_FLUSH_RESPONSE, path cleared

Operating with Higher Layer Protocols After finding the peer MAC address Use BUS Ask the LES the peer ATM, for connection opening IETF proposes ATMARP Server

Next Hop Resolution Protocol ATMs as non-broadcast multi-access network (NBMA) NHRP finds the ATM address of the best next hop

Multiprotocol Over ATM MPOA device ATM interface, LANE software, MPOA client software MPOA server Router containing MPOA server software Shortcut ATM VCC, used instead of the default path A MPOA device requests shortcut information from a MPOA server Shortcuts are opened only at steady traffic

References 13ed_cr/switch_c/xcovlane.htm 13ed_cr/switch_c/xcovlane.htm den.html den.html Dr. Sidnie Feit – “Wide Area High Speed Networks”