Cisco Cisco Prime Unified Operations Manager 8.7 白皮書

 

Operations Manager Deployment Best Practices 

All contents are Copyright © 1992–2006 Cisco Systems, Inc.   All rights reserved. 

Page 85 of 112 

increases beyond 100. To avoid this situation, it is important to plan ahead and optimize 
the span port configuration in the above scenarios. 

 

In a branch office, the density of IP phones is less  than the density seen on the main 
campus. Typically, a branch office will contain fixed-configuration switches and the 
number of simultaneous calls will be fewer.  
In a fairly large branch office, it is common to see multiple fixed-configuration switches 
stacked to provide more density and avoid the need to run a gigabit uplink to an 
aggregate switch/router. The Cisco 1040 Sensor fits into this model the same way as with 
any other switch; the Cisco 1040 still utilizes a span port to monitor the RTP streams

.  

In the scenario where the switches are not stacked, but have gigabit home run to 
aggregate switch, and the number of RTP streams is below 80, then one sensor per switch 
would be overkill. This is where RSPAN (Remote Switched Port Analyzer) becomes 
handy. The configuration done on the switch with respect to SPAN, RSPAN, or ESPAN 
is transparent to the sensor; the sensor functions normally as long as it sees the RTP 
stream. 
In the scenario where RSPAN is not a desirable configuration, or it is not an approved 
configuration, a simple active hub can be used to connect the individual SPAN ports from 
the different switches, and the sensor can be deployed on the hub. It is very important to 
keep spanning tree loops in mind when such a configuration is attempted. The use of a 
hub must be selected as the last resort. 

 

 

The span port is widely used to connect packet sniffers for troubleshooting issues. In the 
contact center world, the span port is used to record the voice conversation. In the service 
monitor world, the span port is used to monitor voice quality. It is quite possible that the 
need may arise to use the span port for packet sniffer, contact center, and service monitor 
at the same time.  
The span port does not allow the configuration of the same source port tied to multiple 
span destination ports; this is one of the limitations of span port configuration. The only 
alternative is to use an active splitter that offers one-to-many streams; the simplest splitter 
can be none other than an active hub that offers one-to-many streams. In this model, the 
packet sniffer, contact center application, and sensor connect to the hub and the hub 
connects to the span destination port on the switch.