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On my 7960, why we have RTP traffic on PC access port???

Hi,

We have CCM 4.1 with 7960. We use voice and data vlan.

When we capture traffic on my laptop connected on PC port of my 7960, we see all the rtp traffic???

Is it very strange??? We do not in the same VLAN: my laptop is in data vlan and my phone is in voice vlan.

Could you explain that???

Thanks for your replay

Regards

S?bastien

2 REPLIES
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Re: On my 7960, why we have RTP traffic on PC access port???

when you do a sniffer capture, it is not vlan dependent.

the sniffer does not know nor care what vlan packets belong to. it simply catches all packets ingress/egress on the port.

since the Phone port is trunked (carry both voice and data vlans aka. DOT1Q'd), all packets are seen by the sniffer.

if the ports in the phone were not DOT1Q'd (trunked) you would only see the packets for the VLAN that was allowed on the port.

Re: On my 7960, why we have RTP traffic on PC access port???

Sebastien,

The 7960 phones have an option called PC Voice Vlan Access in the CCM Phone configuration. The default is on for this. If you don't want your phone traffic to be captured on the PC port disable this. Here is the documentation description.

PC Voice VLAN Access : Indicates whether the phone will allow a device attached to the PC port to access the Voice VLAN. Disabling Voice VLAN Access will prevent the attached PC from sending and receiving data on the Voice VLAN. It will also prevent the PC from receiving data sent and received by the phone. Set this setting to Enabled if an application is being run on the PC that requires monitoring of the phones traffic. These could include monitoring and recording applications and use of network monitoring software for analysis purposes.

This is a required field.

Default: Enabled.

Additionally as an FYI the 7970(and possibly some other newer phones) has a secondary option as well.

Span to PC Port : Indicates whether the phone will forward packets transmitted and received on the Phone Port to the PC Port. Select Enabled if an application is being run on the PC Port that requires monitoring of the IP Phone's traffic such as monitoring and recording applications (common in call center environments) or network packet capture tools used for diagnostic purposes. To use this feature PC Voice VLAN access must be enabled.

This is a required field.

Default: Disabled.

Please rate any helpful posts

Thanks

Fred

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