Download PDF - IBM Redbooks

Chapter 5. ATM Products
In 1994 IBM introduced a solution to ATM in the area of adapters, hubs,
concentrators, internetworking, and management products, as well as WAN.
These products enable you to build and operate your local area networks of any
size and mix protocols and interconnect them.
ATM today plays a key role in the desktop-to-world information highway of the
future. It works equally well on local and wide area networks, and is used in
both private and public networks. ATM is particularly well suited to applications
requiring voice, video, and data traffic types. While enabling new applications,
ATM extends current application solutions hindered by limited bandwidth.
Since most users will not migrate current LANs to ATM overnight, IBM plans for
ATM, as a LAN technology, to coexist for many years with current LANs
(token-ring or Ethernet). This is why IBM has implemented ATM in the IBM 8260
Multiprotocol Intelligent Switching Hub. The IBM 8260 already supports
connectivity to other LANs (Ethernet, token-ring and FDDI). Changing a
workstation connection from current LAN to ATM is similar to changing it from
Ethernet to token-ring: a matter of moving a connector in the wiring cabinet from
a port on a LAN module to a port on an ATM module.
IBM participates in the ATM Forum and has in a statement declared that all IBM
products are to be ATM Forum compliant as the standards are set.
5.1 IBM 8260 ATM Subsystem Mode of Operations
End systems (workstations, bridges, concentrators) connect to the IBM 8260 at
155 Mbps, 100 Mbps and 25 Mbps. End systems can use different modes for
ATM operations:
•
•
•
Classical IP
LAN Emulation
Native ATM
5.1.1 Classical IP
In this mode, the IP protocol runs just above the ATM application adaptation
layer (AAL). The ATM addresses are used in the same way as the LAN
addresses of current LANs (Ethernet or token-ring) were used, namely:
•
When connected through PVC, the end systems exchange their IP addresses.
This is the InATMARP mechanism, similar to the InARP introduced for IP
operation over frame relay.
•
When they want to be connected by SVC, the end systems need to perform
the following steps:
1. Set up a PVC or an SVC with an ARP server, which is a particular end
system attached to the ATM network, in charge of resolving the IP
addresses into ATM addresses.
2. Register their IP address to the ARP server. This way the server will
have the IP address-ATM address mapping of all end systems of the
network.
 Copyright IBM Corp. 1996
247