Discovering connectivity among ATM devices

Asynchronous Transfer Mode (ATM) is an alternative switching protocol for mixed format data (such as pure data, voice, and video). Several types of discovery agents can be used to discover ATM devices on a network.

Note: Before enabling these agents, it is necessary to configure SNMP access and the SNMP Helper.
Table 1. ATM discovery agents
Agent name Function
AtmForumPnni The AtmForumPnni agent retrieves connectivity information from ATM devices that use the Private Network-to-Network Interface (PNNI) dynamic routing protocol and the ATM Forum's PNNI MIB. The PNNI protocol is commonly used on large networks, as it provides ATM switches with a detailed map of the network topology so that the ATM devices can make optimal routing decisions.
CellPath90 The CellPath90 agent enables discovery of the ATM connection of Marconi CellPath 90 WAN (Wide Area Network) multiplexers. The CellPath 90 WAN multiplexer does not know the ATM addresses of its neighbours, so it can only be discovered when it is connected to another, more intelligent, certified ATM device.

The CellPath90 discovery agent is used in the calculation of network topology. It places information about the CellPath 90 into the correct layers within the discovery database.
CiscoPVC The CiscoPVC agent retrieves PVC data from Cisco devices.
ILMI The ILMI agent retrieves connectivity information from devices using the Interim Local Management Interface (ILMI), an RFC standard for managing ATM and IP networks. It investigates how ATM networks are connected down to the layer 2 virtual circuit and port level. This agent also removes logical connectivity from LANE interfaces.
ILMIForeSys The ILMIForeSys agent discovers physical ATM connections between devices by using the ILMI (Interim Local Management Interface) connectivity information provided by the Marconi ASX series of switches.
When connectivity is deduced using ILMI information, it is usually the same as the connectivity that could have been calculated using PNNI information, as is the case with the standard AtmForumPnni and ILMI agents. However, there are some situations where the ILMI information contains details of a connection that is not in the PNNI information, and some situations where the PNNI information details a connection not in the ILMI information. The following examples detail situations where this may be the case:
  • Connections between ASX series switches and SE420/SE440 IADs are only discovered using ILMI.
  • Connections between Cisco routers or switches containing ATM cards and an ATM core are only discovered using ILMI.
  • As with the PnniForeSys agent, the ILMIForeSys agent is designed to operate seamlessly in conjunction with the ILMI agent. A network containing a mixture of ASX devices and another vendor's devices (for example, Cisco 5509 switches with ATM cards) can, therefore, be accurately discovered.
MariposaAtm The MariposaAtm agent discovers the ATM connectivity of the SE420 and SE440 Integrated Access Devices (IADs).

Note: The Ethernet switching and Frame Relay capabilities of these devices are not currently certified.
PnniForeSys The PnniForeSys agent discovers physical ATM connections between devices by using the Private Network-to-Network Interface (PNNI) connectivity information provided by the Marconi ASX series switches. The PnniForeSys agent is designed to operate in conjunction with the AtmForumPnni agent.

The PnniForeSys agent performs extra processing on Fore devices that do not store a logical ifIndex in their pnniLinkIfIndex variable. The information retrieved from these devices requires further processing to retrieve the actual ifIndex, which is held within the ifTable .

Note: SNMP helper configuration for associated devices is a prerequisite for this agent. The AtmForumPnni agent must also be active.