Local SPAN on a C3750

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Feb 11th, 2008
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I am trying to implement a voice recording solution using SPAN on Cisco Cat3750s. We have 13 user switches that connect back to an aggregration switch at 100Mb FD. Each user switch has a SPAN session setup to send all Voice VLAN traffic to the aggregration switch via a 100Mb FD interface. The aggregration switch then has a SPAN session that uses all of the uplink ports to the user switches as sources and sends them to a destination port that has a voice recorder connected. The configs are

User switches

monitor session 1 source vlan (voice vlan)

monitor session 1 destination interface Gi1/0/2 (port to aggregation switch)

Aggregation Switch

monitor session 1 source interface Gi1/0/1 - 13 (uplink ports to user switches)

monitor session 1 destination interface Gi1/0/24 (connection to voice recording server)

When we have more than 7 uplinks open on the aggreation switch its response times are impacted and it begins to work slowly. Does anyone know of any limitations on the number of SPAN source ports you can have?

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royalblues Mon, 02/11/2008 - 04:15
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Why are you setting up span on all the switches?

The span can be configured only on the layer 3 switch where the SVI for the voice vlan is configured.

This is how we set it up in our company. We use verint



sdbrown27 Mon, 02/11/2008 - 05:05
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All our 3750s are running as Layer 2, we have a pair of routers to run the layer 3.

Our network looks like the following


| |

Router Router

\ /

User Switch (x13)


Aggregation Switch


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