9-2 Netra Internet Server 3.1 User’s Manual—September 1996
9
Classical Internet Protocol Interface
Classical IP supports the TCP/IP and 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.
LAN Emulation Interface
LAN Emulation, which provides mechanisms to send broadcast messages, is
another way of supporting the TCP/IP and UDP/IP protocols over an ATM
network. A series of LAN Emulation services (such as the LAN Emulation
Configuration Server (LECS), the LAN Emulation Server (LES), and the
Broadcast and Unknown Server (BUS)) provide address resolution information.
When a LAN Emulation interface is brought up, it joins the LAN by registering
with these services. The LAN Emulation protocol provides a broadcast service
to the upper layer protocols. Therefore, a LAN Emulation interface is not
affected by the multicast and RIP limitations of Classical IP.
Each ATM port on the Netra server currently supports only one LAN
Emulation interface.
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