Classical IP supports the TCP/IP and the User Datagram Protocol/Interface Program (UDP/IP) protocols in an ATM environment. An ATM address resolution protocol (ATM ARP) server replaces the traditional ARP protocol by resolving IP addresses to ATM addresses. It is accessible to all hosts on a subnet. Each host must register with the ARP server when the ATM interface is brought up.
Classical IP has the following limitations because it does not support broadcast and multicast messaging.
Running NIS or NIS+ over Classical IP requires configuration beyond the scope of the ATM module and is not supported.
The Routing Information Protocol (RIP) and the Router Discovery Protocol are not supported. Thus, to route over an ATM network using a Classical IP interface, the Netra server must be configured as a static router. Routes to the routers in the ATM subnet must be explicitly added.
Each ATM port (SBus card) on the Netra server supports only one Classical IP interface.