Thank you all for your support.
I've encountered a strange incident, and I'm very happy to hear your advice.
Two 2960 (WS-C2960S-24TS-L IOS 15.0(2)SE) are connected to each other by GigabitEthernet1/0/21.
The following message was printed during system running
Nov 6 07:51:46.961 JST: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on GigabitEthernet1/0/21 (1), with SW-A GigabitEthernet1/0/24 (3).
I have successfully recovered by rebooting SW-A, but I think that there was something wrong on the SW-A side.
What kind of obstacles do you have? Or is there a bug that matches such an event?
◆When I pressed show cdp neighbor detail on the B side, it seems that Port24 on the A side is connected.
SWB#show cdp neighbors detail
-------------------------
Device ID: SW-A
Entry address(es):
IP address: XX.XXX.79.24
Platform: cisco WS-C2960S-24TS-L, Capabilities: Switch IGMP
Interface: GigabitEthernet1/0/21, Port ID (outgoing port): GigabitEthernet1/0/24
Holdtime : 123 sec
Version :
Cisco IOS Software, C2960S Software (C2960S-UNIVERSALK9-M), Version 15.0(2)SE, RELEASE SOFTWARE (fc1)
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 1986-2012 by Cisco Systems, Inc.
Compiled Sat 28-Jul-12 00:42 by prod_rel_team
advertisement version: 2
Protocol Hello: OUI=0x00000C, Protocol ID=0x0112; payload len=27, value=00000000FFFFFFFF010221FF00000000000008CC68862280FF0000
VTP Management Domain: ''
Native VLAN: 3 (Mismatch)
Duplex: full
Power Available TLV:
Power request id: 0, Power management id: 1, Power available: 0, Power management level: -1
Management address(es):
IP address: XX.XXX.79.24
SW-B#show mac address-table
3 08cc.6886.2297 DYNAMIC Gi1/0/21 <<< SW-A Gi1/0/23 Mac Address
3 08cc.6886.22c1 DYNAMIC Gi1/0/21 <<< SW-A Vlan3 Mac Add
SW-B#show int status GigabitEthernet1/0/21
GigabitEthernet1/0/21 is up, line protocol is up (connected)
Hardware is Gigabit Ethernet, address is 08cc.6886.0515 (bia 08cc.6886.0515)
Description: to SW-A
MTU 1500 bytes, BW 100000 Kbit/sec, DLY 100 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA, loopback not set
Keepalive set (10 sec)
Full-duplex, 100Mb/s, media type is 10/100/1000BaseTX
input flow-control is off, output flow-control is unsupported
ARP type: ARPA, ARP Timeout 04:00:00
Last input 00:00:01, output 00:00:01, output hang never
Last clearing of "show interface" counters never
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: fifo
Output queue: 0/40 (size/max)
5 minute input rate 0 bits/sec, 0 packets/sec
5 minute output rate 1000 bits/sec, 3 packets/sec
43801432 packets input, 3679854700 bytes, 0 no buffer
Received 41353548 broadcasts (39258069 multicasts)
0 runts, 0 giants, 0 throttles
44 input errors, 44 CRC, 0 frame, 0 overrun, 0 ignored
0 watchdog, 39258069 multicast, 0 pause input
0 input packets with dribble condition detected
43659866 packets output, 3723907621 bytes, 0 underruns
0 output errors, 0 collisions, 1 interface resets
0 unknown protocol drops
0 babbles, 0 late collision, 0 deferred
0 lost carrier, 0 no carrier, 0 pause output
0 output buffer failures, 0 output buffers swapped out
◆On the SW-A side, SW-B information is correctly recognized.
SW-A#show cdp neighbors detail
-------------------------
Device ID: SW-B
Entry address(es):
IP address: XX.XXX.80.24
Platform: cisco WS-C2960S-24TS-L, Capabilities: Switch IGMP
Interface: GigabitEthernet1/0/21, Port ID (outgoing port): GigabitEthernet1/0/21
Holdtime : 175 sec
Version :
Cisco IOS Software, C2960S Software (C2960S-UNIVERSALK9-M), Version 15.0(2)SE, RELEASE SOFTWARE (fc1)
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 1986-2012 by Cisco Systems, Inc.
Compiled Sat 28-Jul-12 00:42 by prod_rel_team
advertisement version: 2
Protocol Hello: OUI=0x00000C, Protocol ID=0x0112; payload len=27, value=00000000FFFFFFFF010221FF00000000000008CC68860500FF0000
VTP Management Domain: ''
Native VLAN: 1
Duplex: full
Power Available TLV:
Power request id: 0, Power management id: 1, Power available: 0, Power management level: -1
Management address(es):
IP address: XX.XXX.80.24
SW-B#show mac address-table
4 08cc.6886.0515 DYNAMIC Gi1/0/21 <<< SW-B Gi1/0/21 Mac Address
SW-A#show int status GigabitEthernet1/0/21
GigabitEthernet1/0/21 is up, line protocol is up (connected)
Hardware is Gigabit Ethernet, address is 08cc.6886.2295 (bia 08cc.6886.2295)
Description: to SW-B
MTU 1500 bytes, BW 100000 Kbit/sec, DLY 100 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA, loopback not set
Keepalive set (10 sec)
Full-duplex, 100Mb/s, media type is 10/100/1000BaseTX
input flow-control is off, output flow-control is unsupported
ARP type: ARPA, ARP Timeout 04:00:00
Last input 00:00:01, output 00:00:01, output hang never
Last clearing of "show interface" counte
.Nov 6 12:53:20.779 JST: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet1/0/13, changed state to downrs never
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 83
Queueing strategy: fifo
Output queue: 0/40 (size/max)
5 minute input rate 2000 bits/sec, 3 packets/sec
5 minute output rate 2000 bits/sec, 3 packets/sec
43696783 packets input, 3726750459 bytes, 0 no buffer
Received 41183914 broadcasts (39253813 multicasts)
0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
0 watchdog, 39253813 multicast, 0 pause input
0 input packets with dribble condition detected
43819616 packets output, 3681232987 bytes, 0 underruns
0 output errors, 0 collisions, 1 interface resets
0 unknown protocol drops
0 babbles, 0 late collision, 0 deferred
0 lost carrier, 0 no carrier, 0 pause output
0 output buffer failures, 0 output buffers swapped out
