Understanding span

Answered Question

I have 2 core switches conencted to each other via trunk.

Voip phones are in a seperate vlan and are distributed across both the switches

For recording the conversations i have connected a verint box to the core switch 1 and spanned the entire voice vlan to it.


Does this configuration span the traffic for the vlans on both the switches?

Will it be same if i make core2 as primary gateway and still keep the span on switch1?


Thanks in advance

Correct Answer by royalblues about 9 years 7 months ago

The span would be able to capture all the traffic even from switch 2 since you indicated that switch1 is the primary gateway.


If However for some reason there is an HSRP failover and ur switch2 becomes active, the span configured would not be able to capture the traffic from switch2 as indicated by Jon


HTH

Narayan

Correct Answer by Jon Marshall about 9 years 7 months ago

Hi


You will if you need to route the traffic off that vlan. But you won't if the traffic stays local to the vlan and does not cross the trunk port.


You will need to make sure you include the trunk port in your span session.



Jon

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Jon Marshall Tue, 08/14/2007 - 08:32
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Hi


You don't say which switches you are using but a span session is only local to the switch. If you want to span ports from multiple switches to a destination port you need to look at RSPAN.


Attached is a link to 6500 span configuration which explains the difference between the different types.


http://www.cisco.com/en/US/products/hw/switches/ps708/products_configuration_guide_chapter09186a0080160a5a.html


HTH


Jon

Pavel Bykov Tue, 08/14/2007 - 09:59
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Just like Jon said - it will not span traffic from both switches, only the one where span is configured.


Alternatively, you can configure SPAN ports on both switches and connect them to the box. Usually boxes for voice recording have more than one interface.

Jon,


The switches are 4506. The connection between the 2 is via g1/1 - g1/1

Core switch 1 is the primary gateway for all the voice vlan traffic.


I understand that we need to do RSPAN if we want to span ports from both switches.


But since i am spanning the vlan on switch 1 will i not get all the traffic from switch 2

via the trunk link on G1/1.

Do i still need RSPAN?


thanks

Correct Answer
Jon Marshall Tue, 08/14/2007 - 23:56
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Hi


You will if you need to route the traffic off that vlan. But you won't if the traffic stays local to the vlan and does not cross the trunk port.


You will need to make sure you include the trunk port in your span session.



Jon

Correct Answer
royalblues Wed, 08/15/2007 - 05:36
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The span would be able to capture all the traffic even from switch 2 since you indicated that switch1 is the primary gateway.


If However for some reason there is an HSRP failover and ur switch2 becomes active, the span configured would not be able to capture the traffic from switch2 as indicated by Jon


HTH

Narayan

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