Cisco Support Community
Showing results for 
Search instead for 
Did you mean: 

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. And see here for current known issues.

New Member

7920 and 7921 issue

When I call from a 7920 to 7921 I can not hear anything. And vice versa. However, when I call from any wireless IP phone to a wired IP phone everything works fine. Wireless phones are in the same VLAN.

Any ideas?


Accepted Solutions
New Member

Re: 7920 and 7921 issue

Disable P2P blocking.

New Member

Re: 7920 and 7921 issue

Disable P2P blocking.

New Member

Re: 7920 and 7921 issue


New Member

Re: 7920 and 7921 issue

resolved my issue, thank you

Hall of Fame Super Red

Re: 7920 and 7921 issue

Hi Fuad,

Here is the related setting;

Enabling and Disabling Public Secure Packet Forwarding

Public Secure Packet Forwarding (PSPF) prevents client devices associated to an access point from inadvertently sharing files or communicating with other client devices associated to the access point. It provides Internet access to client devices without providing other capabilities of a LAN. This feature is useful for public wireless networks like those installed in airports or on college campuses.


Note To prevent communication between clients associated to different access points, you must set up protected ports on the switch to which your access points are connected. See the "Configuring Protected Ports" section for instructions on setting up protected ports.


To enable and disable PSPF using CLI commands on your access point, you use bridge groups. You can find a detailed explanation of bridge groups and instructions for implementing them in this document:

•Cisco IOS Bridging and IBM Networking Configuration Guide, Release 12.2. Click this link to browse to the Configuring Transparent Bridging chapter:

You can also enable and disable PSPF using the web-browser interface. The PSPF setting is on the Radio Settings pages.

PSPF is disabled by default. Beginning in privileged EXEC mode, follow these steps to enable PSPF:

Command Purpose

Step 1

configure terminal

Enter global configuration mode.

Step 2

interface dot11radio { 0 | 1 }

Enter interface configuration mode for the radio interface. The 2.4-GHz radio is radio 0, and the 5-GHz radio is radio 1.

Step 3

bridge-group group port-protected

Enable PSPF.

Step 4


Return to privileged EXEC mode.

Step 5

copy running-config startup-config

(Optional) Save your entries in the configuration file.

Use the no form of the command to disable PSPF.

If you are using the WLC;

Configuring Peer-to-Peer Blocking

In controller software releases prior to 4.2, peer-to-peer blocking is applied globally to all clients on all WLANs and causes traffic between two clients on the same VLAN to be transferred to the upstream VLAN rather than being bridged by the controller. This behavior usually results in traffic being dropped at the upstream switch because switches do not forward packets out the same port on which they are received.

In controller software release 4.2, peer-to-peer blocking is applied to individual WLANs, and each client inherits the peer-to-peer blocking setting of the WLAN to which it is associated.

Hope this helps!


Cisco Employee

Re: 7920 and 7921 issue

Yes PSPF must be disabled for the voice vlan/ssid.

If the 2 wlan phones are on separate aps does the audio work?

If using the WLAN Controller, then P2P Blocking Action must be disabled for the voice ssid.

P2P Blocking Action

Configures the peer-to-peer blocking settings.

Disabled - (Default) Disables peer-to-peer blocking and bridges traffic locally within the controller whenever possible.

Note Traffic is never bridged across VLANs in the controller.

Drop - Causes the controller to discard the packets.

Forward-UpStream - Causes the packets to be forwarded on the upstream VLAN. The device above the controller decides what action to take regarding the packets.

CreatePlease to create content