CDP本地VLAN失配

Question

我得到CDP本机VLAN不匹配日志在我的思科3750 x交换机栈。Gig 2/0/5和Gig 4/0/6根本不存在物理连接(如下面所示，1/0/44和2/0/13两者都不是)。我通过堆栈电缆互连每个开关。在这方面，我没有看到任何性能问题。可能是窃听器？我在以下所有交换机上运行15.2(4)E9

Dec  6 17:06:11: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on GigabitEthernet2/0/5 (10), with 3750X_STACK GigabitEthernet4/0/6 (50).
Dec  6 17:06:11: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on GigabitEthernet2/0/5 (10), with 3750X_STACK GigabitEthernet4/0/6 (50). (3750X_STACK-2)
Dec  6 17:07:07: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on GigabitEthernet4/0/6 (50), with 3750X_STACK GigabitEthernet2/0/5 (10).
Dec  6 17:07:07: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on GigabitEthernet4/0/6 (50), with 3750X_STACK GigabitEthernet2/0/5 (10). (3750X_STACK-4)
Dec  6 17:07:10: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on GigabitEthernet2/0/5 (10), with 3750X_STACK GigabitEthernet4/0/6 (50).
Dec  6 17:07:10: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on GigabitEthernet2/0/5 (10), with 3750X_STACK GigabitEthernet4/0/6 (50). (3750X_STACK-2)
Dec  6 17:07:59: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on GigabitEthernet2/0/5 (10), with 3750X_STACK GigabitEthernet4/0/6 (50).
Dec  6 17:07:59: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on GigabitEthernet2/0/5 (10), with 3750X_STACK GigabitEthernet4/0/6 (50). (3750X_STACK-2)
Dec  6 17:08:07: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on GigabitEthernet4/0/6 (50), with 3750X_STACK GigabitEthernet2/0/5 (10).
Dec  6 17:08:07: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on GigabitEthernet4/0/6 (50), with 3750X_STACK GigabitEthernet2/0/5 (10). (3750X_STACK-4)

3750X_STACK#show switch detail
Switch/Stack Mac Address : xxxx.xxxx.xxxx
                                           H/W   Current
Switch#  Role   Mac Address     Priority Version  State
----------------------------------------------------------
*1       Master xxxx.xxxx.xxxx     15     3       Ready
 2       Member xxxx.xxxx.xxxx     1      3       Ready
 3       Member xxxx.xxxx.xxxx     1      3       Ready
 4       Member xxxx.xxxx.xxxx     1      3       Ready



         Stack Port Status             Neighbors
Switch#  Port 1     Port 2           Port 1   Port 2
--------------------------------------------------------
  1        Ok         Ok                2        4
  2        Ok         Ok                3        1
  3        Ok         Ok                4        2
  4        Ok         Ok                1        3

3750X_STACK#show cdp neighbors
Capability Codes: R - Router, T - Trans Bridge, B - Source Route Bridge
                  S - Switch, H - Host, I - IGMP, r - Repeater, P - Phone,
                  D - Remote, C - CVTA, M - Two-port Mac Relay

Device ID        Local Intrfce     Holdtme    Capability  Platform  Port ID
3750X_STACK
                 Gig 2/0/5         171             R S I  WS-C3750X Gig 4/0/6
3750X_STACK
                 Gig 4/0/6         131             R S I  WS-C3750X Gig 2/0/5
3750X_STACK
                 Gig 2/0/13        150             R S I  WS-C3750X Gig 1/0/44
3750X_STACK
                 Gig 1/0/44        147             R S I  WS-C3750X Gig 2/0/13

Switch Ports Model                     SW Version            SW Image
------ ----- -----                     ----------            ----------
*    1 54    WS-C3750X-48P             15.2(4)E9             C3750E-UNIVERSALK9-M
     2 54    WS-C3750X-48P             15.2(4)E9             C3750E-UNIVERSALK9-M
     3 54    WS-C3750X-48P             15.2(4)E9             C3750E-UNIVERSALK9-M
     4 54    WS-C3750X-48P             15.2(4)E9             C3750E-UNIVERSALK9-M

3750X_STACK#show run interface gigabitEthernet 2/0/5
Building configuration...

Current configuration : 151 bytes
!
interface GigabitEthernet2/0/5
 switchport access vlan 10
 switchport trunk encapsulation dot1q
 switchport mode access
end

3750X_STACK#show run interface gigabitEthernet 4/0/6
Building configuration...

Current configuration : 106 bytes
!
interface GigabitEthernet4/0/6
 switchport access vlan 50
 switchport mode access
end

Answer 1

当交换机下游的某个部分不理解CDP并错误地处理流量时，就会发生这种情况。所以，有东西把2/0/5和4/0/6连接起来，你会找到它的。(有人有一个哑交换机，或者是哑VM泄漏的流量)

Answer 2

例如，当两个交换机与访问端口连接，并且这些访问端口位于不同的VLAN中时，就会发生这种情况。在某些情况下，这是故意的，在某些情况下，这是一个错误，这就是为什么警告。虽然以太网帧本身没有VLAN标记，但CDP帧中包含端口的本地VLAN，因此当交换机从CDP公告中的另一个具有VLAN X的交换机接收CDP邻居通知时，并且接收通知的端口与X具有不同的本地VLAN，则会记录此警告。

如果这种VLAN不匹配是故意的，则可以使用以下方法对该端口关闭这些警告：

no cdp log mismatch native