Pls provide some solution.

[vinothlb1]

i m getting the following log message which causes entire network down where we connected 50 switches and 700 users pc connected. This the log message i m getting in cisco 4000 L3 switch . In port Gi2/15 i have connected up link of another floor where 3 switches are connected..( with 2 switches connected to uplink there is no issue whe i connected my third switch causes entire n/w down) whenever i disconnected gi2/15 everything works fine but when i plugged in gi2/15 which causes entite network down. And port Fa3/44 where i connected my Cisco 3600 series Router . Pls provide any suggestion how to avoid this problem..

May 27 09:32:19: %C4K_EBM-4-HOSTFLAPPING: Host 00:0C:85:7A:16:01 in vlan 1 is f

lapping between port Gi2/15 and port Fa3/44

.May 27 09:32:21: %C4K_EBM-4-HOSTFLAPPING: Host 00:0C:85:7A:16:01 in vlan 1 is f

lapping between port Fa3/44 and port Gi2/15

.May 27 11:22:07: %SPANTREE-7-RECV_1Q_NON_TRUNK: Received 802.1Q BPDU on non tru

nk GigabitEthernet2/15 VLAN1.

.May 27 11:22:07: %SPANTREE-7-BLOCK_PORT_TYPE: Blocking GigabitEthernet2/15 on V

LAN0001. Inconsistent port type.

.May 27 11:23:04: %SPANTREE-2-UNBLOCK_CONSIST_PORT: Unblocking GigabitEthernet2/

15 on VLAN0001. Port consistency restored.

.May 27 11:23:35: %SPANTREE-7-RECV_1Q_NON_TRUNK: Received 802.1Q BPDU on non tru

nk GigabitEthernet2/15 VLAN1.

.May 27 11:23:35: %SPANTREE-7-BLOCK_PORT_TYPE: Blocking GigabitEthernet2/15 on V

LAN0001. Inconsistent port type.

.May 27 11:23:50: %SPANTREE-2-UNBLOCK_CONSIST_PORT: Unblocking GigabitEthernet2/

15 on VLAN0001. Port consistency restored.

.May 27 11:24:38: %SPANTREE-7-RECV_1Q_NON_TRUNK: Received 802.1Q BPDU on non tru

nk GigabitEthernet2/15 VLAN1.

.May 27 11:24:38: %SPANTREE-7-BLOCK_PORT_TYPE: Blocking GigabitEthernet2/15 on V

LAN0001. Inconsistent port type.

.May 27 11:25:01: %SPANTREE-2-UNBLOCK_CONSIST_PORT: Unblocking GigabitEthernet2/

15 on VLAN0001. Port consistency restored.

May 27 13:26:55: %C4K_L2MAN-6-INVALIDSOURCEADDRESSPACKET: (Suppressed 129 times)

Packet received with invalid source MAC address (00:00:00:00:00:00) on port Gi2/

18 in vlan 1

May 27 19:54:20: %C4K_L2MAN-6-INVALIDSOURCEADDRESSPACKET: (Suppressed 3 times)Pa

cket received with invalid source MAC address (00:00:00:00:00:00) on port Gi2/18

in vlan 1

May 28 03:21:48: %DTP-5-DOMAINMISMATCH: Unable to perform trunk negotiation on p

ort Gi2/24 because of VTP domain mismatch.

[darren-carr]

Hi

Looking at the log.. is port Gi 2/15 an access port or trunk port? If you are carrying multiple vlans you will have to configure port Gi 2/15 as a trunk port

switch#

switch#config t

switch3#int g 2/15

switch#switchport mode trunk

It looks as though the connected switch is trying to forward a BPDU and it is being blocked....

I would also check your VTP configuration on your switches looks like you have inconsistent configurations. Looks like you have another switch connected on port G2/24

I would start by checking how the port Gi2/15 is configured and then review your VTP configuration across your switches. Be very careful though as if you have 50 switches connected and your VTP configuration is not configured properly you risk the possibility that you could wipe all VLAN information!!! Approach with a lot of caution. Start by trying to identify the VTP servers, clients, mode they are configured in, etc and then map it out with a document before making any changes..I understand why you are using VTP with the amount of switches but it also can be dangerous! It may be that the switch attached to Gi2/24 is the only one that is misconfigured..as I say be very careful!

Good luck

D