PC can't communicate when IP Phone 7941 registered

[digit29]

Hi,

I have an infrastructure with Cisco IP Phone 7941 + PC running Win10 connected

to a switch from HPE 'R5130'.

With IP phones like 7941 or 7961 plus a PC connected behind, when the IP phone finishes registering

the PC is disconnected.

However PC is still authenticated with dot1x and IP Phone authenticated via Mac-Auth.

Until now we don't understand why the communication on the PC port of the IP Phone

is cut when the IP Phone is registered.

I have given the reference of the IP Phone 7941 below.

I have looked at the settings of the Ip Phone but nothing special.

PS: with IP Phones 7940, 7942 or 7960 it works fine but these IP phones have few lldp features

*****************************************************************************

 System description  : Cisco IP Phone 7941G,V1, SCCP41.9-4-2SR1-1S

 System capabilities supported : Bridge, Telephone
 System capabilities enabled   : Bridge, Telephone
 Management address type           : IPv4

 FirmwareRev                : 7941G_64-02070631Amd64megRel.bin
 SoftwareRev                : SCCP41.9-4-2SR1-1S
 SerialNum                  : FCH10489J3G
 Manufacturer name          : Cisco Systems, Inc.
 Model name                 : CP-7941G

***************************************************************************

regards.

[HARIS_HUSSAIN]

Does it work when u disable dot1x authentication and register phone?

[digit29]

Hi,

Thanks for the answer.

We haven't tested to disable  the dot1x for the PC because dot1x has to be maintained.

Even when the connection is cut on The PC and the IP Phone still working

by running display mac, we still see both terminals authenticated 

[xx-GigabitEthernet1/0/1]dis mac-address int g1/0/1
MAC Address      VLAN ID    State            Port/NickName            Aging
40b0-34ec-b24b   10         DOT1X            GE1/0/1                  N    <== PC
001a-6d70-c728   26         AUTH             GE1/0/1                  N     <== IP Phone 7941

In the config of the port Gi1/0/1 we have following lldp commands:

lldp compliance admin-status cdp txrx
lldp tlv-enable med-tlv network-policy xx

We have analyzed debug datas taken  on the switch but nothing abnormal found.

I don't know if on the IP Phone we can find interesting info.

regards.