flapping interface up/down

chpmotry · ‎05-29-2023

hi guys.

i have a switch 2960s-48ts-s that connected to rb912uag mikrotik. in other side the rb connected to router 2811 .

in both sides the ether port between cisco devices and mikrotik devices is upped and downed alternately .

The port turns off and on irregularly at different times. the logging show the below data:

in switch:

int g0/2
switchport access vlan 10
switchport mode access

-------------

:06:43.113: %LINK-3-UPDOWN: Interface GigabitEthernet0/2, changed state to down
*Jan 7 15:07:01.191: %LINK-3-UPDOWN: Interface GigabitEthernet0/2, changed state to up
*Jan 7 15:07:02.192: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet0/2, changed state to up
*Jan 7 15:16:18.174: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet0/2, changed state to down
*Jan 7 15:16:19.175: %LINK-3-UPDOWN: Interface GigabitEthernet0/2, changed state to down
*Jan 7 15:16:56.274: %LINK-3-UPDOWN: Interface GigabitEthernet0/2, changed state to up
*Jan 7 15:16:57.275: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet0/2, changed state to up
*Jan 7 15:25:36.089: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet0/2, changed state to down
*Jan 7 15:25:37.091: %LINK-3-UPDOWN: Interface GigabitEthernet0/2, changed state to down
*Jan 7 15:26:14.158: %LINK-3-UPDOWN: Interface GigabitEthernet0/2, changed state to up
*Jan 7 15:26:15.159: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet0/2, changed state to up
*Jan 7 15:26:19.569: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet0/2, changed state to down
*Jan 7 15:26:20.570: %LINK-3-UPDOWN: Interface GigabitEthernet0/2, changed state to down
*Jan 7 15:26:38.212: %LINK-3-UPDOWN: Interface GigabitEthernet0/2, changed state to up
*Jan 7 15:26:39.219: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet0/2, changed state to up
*Jan 7 15:27:03.834: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet0/2, changed state to down
*Jan 7 15:27:04.836: %LINK-3-UPDOWN: Interface GigabitEthernet0/2, changed state to down
*Jan 7 15:27:21.744: %LINK-3-UPDOWN: Interface GigabitEthernet0/2, changed state to up
*Jan 7 15:27:22.745: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet0/2, changed state to up
*Jan 7 15:27:44.734: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet0/2, changed state to down
*Jan 7 15:27:45.735: %LINK-3-UPDOWN: Interface GigabitEthernet0/2, changed state to down
*Jan 7 15:28:22.934: %LINK-3-UPDOWN: Interface GigabitEthernet0/2, changed state to up
*Jan 7 15:28:25.078: %LINK-3-UPDOWN: Interface GigabitEthernet0/2, changed state to down
*Jan 7 15:28:43.161: %LINK-3-UPDOWN: Interface GigabitEthernet0/2, changed state to up
*Jan 7 15:28:44.162: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet0/2, changed state to up
*Jan 7 15:28:46.411: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet0/2, changed state to down
*Jan 7 15:28:47.413: %LINK-3-UPDOWN: Interface GigabitEthernet0/2, changed state to down
*Jan 7 15:29:05.726: %LINK-3-UPDOWN: Interface GigabitEthernet0/2, changed state to up
*Jan 7 15:29:06.727: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet0/2, changed state to up
*Jan 7 16:14:01.998: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet0/2, changed state to down
*Jan 7 16:14:03.004: %LINK-3-UPDOWN: Interface GigabitEthernet0/2, changed state to down
*Jan 7 16:14:40.805: %LINK-3-UPDOWN: Interface GigabitEthernet0/2, changed state to up
*Jan 7 16:14:41.807: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet0/2, changed state to up
*Jan 7 16:15:11.681: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet0/2, changed state to down
*Jan 7 16:15:12.682: %LINK-3-UPDOWN: Interface GigabitEthernet0/2, changed state to down
*Jan 7 16:15:29.276: %LINK-3-UPDOWN: Interface GigabitEthernet0/2, changed state to up
*Jan 7 16:15:30.277: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet0/2, changed state to up
*Jan 7 17:05:41.148: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet0/2, changed state to down
*Jan 7 17:05:42.149: %LINK-3-UPDOWN: Interface GigabitEthernet0/2, changed state to down
*Jan 7 17:06:19.049: %LINK-3-UPDOWN: Interface GigabitEthernet0/2, changed state to up
*Jan 7 17:06:20.050: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet0/2, changed state to up

sh int g0/2
GigabitEthernet0/2 is up, line protocol is up (connected)
Hardware is Gigabit Ethernet, address is .....

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 00:00:27, output 00:00:00, output hang never
Last clearing of "show interface" counters 1w2d
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 271964
Queueing strategy: fifo
Output queue: 0/40 (size/max)
5 minute input rate 79000 bits/sec, 44 packets/sec
5 minute output rate 355000 bits/sec, 46 packets/sec
31144613 packets input, 5008047060 bytes, 0 no buffer
Received 477574 broadcasts (449047 multicasts)
0 runts, 0 giants, 0 throttles
1 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
0 watchdog, 449047 multicast, 0 pause input
0 input packets with dribble condition detected
46577778 packets output, 56331511698 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

--------------

in router 2811:

int f0/1

ip add 192.168.1.1 255.255.255.0

sh int f0/1
FastEthernet0/1 is up, line protocol is up
Hardware is .... Ethernet, address is .....
Internet address is
MTU 1500 bytes, BW 100000 Kbit/sec, DLY 100 usec,
reliability 255/255, txload 1/255, rxload 2/255
Encapsulation ARPA, loopback not set
Keepalive set (10 sec)
Full-duplex, 100Mb/s, 100BaseTX/FX
ARP type: ARPA, ARP Timeout 04:00:00
Last input 00:00:00, output 00:00:00, 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 807000 bits/sec, 82 packets/sec
5 minute output rate 86000 bits/sec, 68 packets/sec
59659829 packets input, 1164540056 bytes
Received 115434 broadcasts, 0 runts, 0 giants, 0 throttles
1 input errors, 0 CRC, 1 frame, 0 overrun, 0 ignored
0 watchdog
0 input packets with dribble condition detected
38795709 packets output, 1119407562 bytes, 0 underruns
0 output errors, 0 collisions, 0 interface resets
104 unknown protocol drops
0 babbles, 0 late collision, 0 deferred
0 lost carrier, 0 no carrier
0 output buffer failures, 0 output buffers swapped out

-------

The interesting thing that is shown is the large amount of Total output drops in switch 2960s. why this feauture is big amount?

my poe and cable and mikrotik rb are new .how i resolve this problem ?

pieterh · ‎05-31-2023

your question concentrates on the output of the Cisco switch
but my guess is that the wireless connection between the two Mikrotik devices is intermittent
hence the port of the Mikrotik to the Cisco is flagged down intermittently

=> check the logging on the mikrotik
you may better contact a mikrotik forum than a Cisco forum for this.
but start by checking there are no intermittent/moving obstacles between wireless transmitter/receiver (sliding door maybe ?)

chpmotry · ‎06-03-2023

thank you pieterh.

i'm disabled the wireless card of radio for test this state and the flapping of ethernet occured again. then this problem is not related to wireless stability

Flavio Miranda · ‎06-03-2023

Hi @chpmotry

I believe the up and down and the output drop can be different problems. The interface up/down I would recommend review the cable, if possible change the port on both devices, test with config in "auto" and "no auto" for speed and duplex.

Output drop I would first clear the counters and monitor. We dont know how long those counts are there. If the counters increase fast again then it is something to worry. Usually this problem is related to hardware capacity.

chpmotry · ‎06-26-2023

configure of router 2800:
interface FastEthernet0/1
bandwidth 100000
ip address 172.16.118.4 255.255.255.0
duplex auto
speed 100
--------------------

detail of ether that connected to mikrotik radio

R-2800#sh int f0/1
FastEthernet0/1 is up, line protocol is up
Hardware is MV96340 Ethernet, address is 1c17.d339.d5b1 (bia 1c17.d339.d5b1)
Internet address is 172.16.118.4/24
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, 100BaseTX/FX
ARP type: ARPA, ARP Timeout 04:00:00
Last input 00:00:00, output 00:00:00, output hang never
Last clearing of "show interface" counters 6d21h
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 749000 bits/sec, 89 packets/sec
5 minute output rate 125000 bits/sec, 71 packets/sec
30715186 packets input, 198745774 bytes
Received 59733 broadcasts, 0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
0 watchdog
0 input packets with dribble condition detected
19378370 packets output, 2296208868 bytes, 0 underruns
75 output errors, 644 collisions, 3 interface resets
330 unknown protocol drops
0 babbles, 75 late collision, 0 deferred
0 lost carrier, 0 no carrier
0 output buffer failures, 0 output buffers swapped out

config of ether duplex & speed of radio

config duplex in mikrotik radio

log of radio mikrotik :

pieterh · ‎06-27-2023

I'd suggest to match the Microtik's port to the Cisco's

Cisco:
interface FastEthernet0/1
duplex auto
speed 100

1) as it al ready is a Fast Ethernet port the speed is implicitly 100Mbps, so bandwidth setting is not necessary
2) Cisco (c.q. most vendors) recommends configuring both ends for auto or both ends fixed
- remove the "speed 100" on the cisco interface or change to "speed auto 100"
- on the Microtik move the 100Mbps/FullDuplex to the first position, so this will be the first choise in negotiation
- if possible set the other speeds on "no advertise"
with this combination you still have autonegotiation enabled on both sides, but the result can only be 100Mbps/full-duplex
3) if this still has problems, then try the same with 100Mbps/half duplex
4) last : try with fixed speed/duplex, but then on both devices

chpmotry · ‎06-27-2023

thanks for your answer.

Is it possible that the problem is related to the non-standard cable or its sockets?

But I think it is unlikely because CRC, Total output drops: 0

pieterh · ‎06-27-2023

>>> Is it possible ... <<<
yes it is possible
apart from cables that are not fabricated correctly , occasionally a brand of cable/connector do not work well with a certain device
(like the fit of a size 7 shoe can differ between brands)
so yes if possible get another brand of cable and swap