Remote Network Monitoring (RMON) is an Internet Engineering Task Force (IETF) standard monitoring specification that allows various network agents and console systems to exchange network monitoring data. RMON is disabled by default, and no events or alarms are configured in the switch. You can configure your RMON alarms and events by using the CLI or an SNMP-compatible network management station to monitor Cisco MDS 9000 Family switches.

All switches in the Cisco MDS 9000 Family support the following RMON functions (defined in RFC 2819):

Alarm: Each alarm monitors a specific management information base (MIB) object for a specified interval. When the MIB object value exceeds a specified value (rising threshold), the alarm condition is set, and only one event is triggered regardless of how long the condition exists. When the MIB object value falls below a certain value (falling threshold), the alarm condition is cleared. This allows the alarm to trigger again when the rising threshold is crossed again.

Event: Determines the action to take when an event is triggered by an alarm. The action can be to generate a log entry, an SNMP trap, or both.

SPAN

The Switched Port Analyzer (SPAN) feature is supported by switches in the Cisco MDS 9000 Family. It monitors network traffic through a Fibre Channel interface. Traffic through any Fibre Channel interface can be replicated to a special port called the SPAN destination port (SD port). Any Fibre Channel port in a switch can be configured as an SD port. When an interface is in SD port mode, it cannot be used for normal data traffic. You can attach a Fibre Channel analyzer to the SD port to monitor SPAN traffic, as shown in Figure 11-3.

Figure 11-3 SPAN Transmission

SD ports do not receive frames; they only transmit a copy of the SPAN source traffic. The SPAN feature is nonintrusive and does not affect switching of network traffic for any SPAN source ports.

SPAN sources refer to the interfaces from which traffic can be monitored. You can also specify VSAN as a SPAN source, in which case, all supported interfaces in the specified VSAN are included as SPAN sources. When a VSAN as a source is specified, all physical ports and port channels in that VSAN are included as SPAN sources. A TE port is included only when the port VSAN of the TE port matches the source VSAN. A TE port is excluded even if the configured allowed VSAN list may have the source VSAN, but the port VSAN is different. You cannot configure source interfaces (physical interfaces, port channels, or sup-fc interfaces) and source VSANs in the same SPAN session.

You can choose the SPAN traffic in the ingress direction, the egress direction, or both directions for any source interface:

Ingress source (Rx): Traffic entering the switch fabric through this source interface is spanned, or copied, to the SD port, as shown in Figure 11-4.

Figure 11-4 SPAN Traffic from the Ingress Direction

Egress source (Tx): Traffic exiting the switch fabric through this source interface is spanned, or copied, to the SD port, as shown in Figure 11-5.

Figure 11-5 SPAN Traffic from the Egress Direction

The SPAN feature is available for the following interface types:

Physical ports: These port types include F, FL, TE, E, and TL ports.