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Classical IP-Over-ATM (IPOA RFC 1577)
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ATM is a connection-oriented protocol, which means that connection must be established between two communicating entities before data transfer can begin. IP is inherently connectionless. There are 2 ways to run transparently IP traffic over ATM: Classical IP and LAN emulation
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The term "classical" indicates that the ATM network has the same properties as existing legacy LANs.
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SVC management is performed via UNI specification, which defines signaling: Q.93B (UNI3.0), Q.2931 (UNI3.1).
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Once a Classical IP connection has been established, IP datagrams are encapsulated using IEEE 802.2 LLC/SNAP and are segmented into ATM cells using AAL5.
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There is no support for broadcast and multicast in a Classical IP environment. The Classical network is divided into LISs (Logical IP Subnets).
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Each LIS must have only on ATM ARP server configured on a switch or a host ARP server is responsible for resolving an IP addresses into ATM addresses.
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