This soft copy for use by IBM employees only.
CIP Address Registration: Because in CIP there is no function analogous to the LECS in LANE, each endstation must be configured with the ATM address of its ARP server. The ARP client establishes a connection to the ARP server, and notifies it of its IP address and its ATM address. The ARP server adds these to its ARP table, so that it can respond properly to other ARP requests.
CIP Address Resolution: When a CIP client wishes to establish IP communication with another IP device, it issues an ARP to the ARP server to determine the ATM address of the other device. If the ARP server has an entry that matches the IP address of the requested device, it returns the ATM address of that device to the requesting endstation, which caches it in its own ARP table. If however, the ARP server doesn′t have the IP address in its ARP table, it returns an ARP_FAILURE to the requesting client. The client now forwards the unresolvable address to its default gateway for further handling. If the gateway can resolve the address, it returns its IP and ATM addresses to the client to be cached. If the gateway cannot resolve the address, it returns an ARP_FAILURE to the client and the address resolution process terminates.
CIP Data Forwarding: When a device wishes to forward data to another CIP device, it must first check to see if it knows the other device′s ATM address (that is, its ARP table contains an entry for the desired destination device). If so, it merely establishes a direct connection with the other device, and forwards data to it. If not, it must first resolve the address (see ªCIP Address Resolutionº above), then setup a connection, and then forward data directly.
A more complete discussion of Classical IP can be found in IBM 8260 As a Campus ATM Switch,
Chapter 1. Introduction to ATM Networks 7
