3 Seconds Recurrent %LINEPROTO-5-UPDOWN Link Flap Issue

[Batelco]

Dear Support Community.

I noticed the following log appears on one side of the link. the other switch has no such flapping recorded "C3750". The way they were set-up is that C3750 gets extended from C3550, only C3550 is alerting of the issue in the log. I noticed that the alert is generated when a user connected to C3750  Ethernet gig port opens an intranet or WAN page and during this time any telnet session hangs for 3 second exactly as well but the alert is not generated in it "C3750" it is on the main switch C3550 . I already checked that the SFP on C3750 is up to spec and the patch cord is new out of the bag. What has gone wrong? both end interfaces speed and duplex are set to auto and both are at full duplex and speed 1000. Desktop NIC drivers were also updated to hp latest site driver

Have I done something wrong? so far I visited the location 3 times which is also far. any input will be quiet helpful.

Your help is really appreciated

005845: Jan 14 06:03:54 GMT: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet0/2, changed state to up
005846: Jan 14 06:08:00 GMT: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet0/2, changed state to down
005847: Jan 14 06:08:03 GMT: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet0/2, changed state to up
005848: Jan 14 06:08:41 GMT: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet0/2, changed state to down
005849: Jan 14 06:08:44 GMT: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet0/2, changed state to up
005850: Jan 14 06:40:11 GMT: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet0/2, changed state to down
005851: Jan 14 06:40:14 GMT: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet0/2, changed state to up
005852: Jan 14 06:40:54 GMT: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet0/2, changed state to down
005853: Jan 14 06:40:57 GMT: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet0/2, changed state to up

[Georg Pauwen]

Hello,

is there a specific reason you have VLAN 2 configured as the native VLAN on both switches and trunks ? Can you post the output of 'show spanning-tree vlan 2' from both switches ?

[Batelco]

---

@Georg Pauwen wrote:

Hello,

is there a specific reason you have VLAN 2 configured as the native VLAN on both switches and trunks ? Can you post the output of 'show spanning-tree vlan 2' from both switches ?

---

Dear Georg,

Kindly note I don't think the native vlan is creating the issue as we have an existing set-up in a different location only that branch is getting extended thru BGP, and this branch gets extended through Access. I have removed all clients from the second switch to not cause disturbance in the lab meanwhile I find a feasible solution. I have also removed native vlan command.

C3550

VLAN0002
  Spanning tree enabled protocol ieee
  Root ID    Priority    32770
             Address     000e.8355.ec80
             This bridge is the root
             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

  Bridge ID  Priority    32770  (priority 32768 sys-id-ext 2)
             Address     000e.8355.ec80
             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec
             Aging Time 300

Interface        Role Sts Cost      Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
Fa0/1            Desg FWD 19        128.1    P2p
Fa0/2            Desg FWD 19        128.2    Edge P2p
Fa0/3            Desg FWD 19        128.3    Edge P2p
Fa0/6            Desg FWD 19        128.6    Edge P2p
Fa0/7            Desg FWD 19        128.7    Edge P2p
Fa0/8            Desg FWD 19        128.8    Edge P2p
Fa0/9            Desg FWD 19        128.9    Edge P2p
Fa0/10           Desg FWD 19        128.10   Edge P2p
Fa0/12           Desg FWD 19        128.12   Edge P2p
Fa0/13           Desg FWD 19        128.13   Edge P2p
Fa0/14           Desg FWD 19        128.14   Edge P2p
Fa0/17           Desg FWD 19        128.17   Edge P2p
Fa0/19           Desg FWD 19        128.19   Edge P2p
Fa0/20           Desg FWD 100       128.20   Edge P2p
Fa0/21           Desg FWD 19        128.21   Edge P2p
Fa0/23           Desg FWD 19        128.23   Edge P2p
Fa0/24           Desg FWD 19        128.24   Edge P2p
Gi0/2            Desg FWD 4         128.26   P2p

#########################################################################

#########################################################################

C3750

VLAN0002
  Spanning tree enabled protocol ieee
  Root ID    Priority    32770
             Address     000e.8355.ec80
             Cost        4
             Port        25 (GigabitEthernet1/0/25)
             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec

  Bridge ID  Priority    32770  (priority 32768 sys-id-ext 2)
             Address     0024.f9aa.d980
             Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec
             Aging Time 300

Interface        Role Sts Cost      Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
Gi1/0/25         Root FWD 4         128.25   P2p

[Georg Pauwen]

Hello,

looking at your configuration again, I noticed that your 3750 switch is in 'vtp mode transparent'. How is your VTP set up ? A switch in transparent mode does not get VLAN information, that might be the problem. I would suggest to set up a VTP domain with one switch as the VTP server and the other as VTP client...

[Batelco]

Dear Georg,

The VTP has been set to transparent to ensure that it won't override with the main switch, yes you are right that it won't get VTP Information, but since the vlan name is created locally with it's interface vlan as a management IP address, and the IP default gateway is set to 10.5.13.1 which is pointing at the main branch switch the VTP would be neglected. I will note down your remarks and check it next time I visit. but kindly note that the other branch has same config with no recorded issues. Attached the working set-up note the difference is this set up uses a WAN protocol BGP to forward packets from/to.

Kind Regards,

Abdulla Sharaf

[Batelco]

I came across this discussion

https://supportforums.cisco.com/t5/lan-switching-and-routing/c3750-stack-lineproto-5-updown-all-three-seconds/td-p/1453670

so my plan is to crimp a crossover cable since C3550 does not support auto MDIX and create an Ethernet uplink similarly to the configured fiber interfaces just as Ethernet, and re test the set-up. I will keep you posted if that worked.

Regards,

Abdulla Sharaf

[Leo Laohoo]

Post the complete output to the command "sh interface G0/2".

[Batelco]

Dear Leo,

Thank you for reading through, here's the output as requested:

BCNCT-HMDRTLEX-3X198#show interfaces gi0/2
GigabitEthernet0/2 is up, line protocol is up (connected)
  Hardware is Gigabit Ethernet, address is 000e.8355.ec9a (bia 000e.8355.ec9a)
  Description: BCNCT-HMDRTLEX-3X198
  MTU 1500 bytes, BW 1000000 Kbit, DLY 10 usec,
     reliability 255/255, txload 1/255, rxload 1/255
  Encapsulation ARPA, loopback not set
  Keepalive set (10 sec)
  Full-duplex, 1000Mb/s
  Link type is autonegotiation, media type is LX
  output flow-control is off, input flow-control is off
  ARP type: ARPA, ARP Timeout 04:00:00
  Last input 00:00:26, 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 ouxtput rate 0 bits/sec, 0 packets/sec
     1068319 packets input, 185977785 bytes, 0 no buffer
     Received 156693 broadcasts, 0 runts, 0 giants, 0 throttles
     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
     0 watchdog, 82807 multicast, 0 pause input
     0 input packets with dribble condition detected
     3498187 packets output, 1733436064 bytes, 0 underruns
     0 output errors, 0 collisions, 4 interface resets
     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

interface GigabitEthernet0/2
 description BCNCT-HMDRTLEX-3X198
 switchport trunk encapsulation dot1q
 switchport mode trunk
 no ip address
end

Kind Regards,

Abdulla Sharaf

[Batelco · Accepted solution]

Just in case someone stumbled across a similar issue. the link flap which was occurring excessively between the main branch switch and the newly installed one was caused by a hardware defect from the main switch as the other side of the link was not registering any flaps. I bypassed the trunking through fiber channel and crimped a cross-over Ethernet cable as the C3550 does not support auto MDIX like the newer models, connected each side of interface and before issuing no shut command I unplugged the fiber cable to ensure that STP would not interfere and block the Ethernet link. flaps are gone so it was either the pluggable fiber unit on C3550 or the controller that is running behind it that was malfunctioning. Other things that I applied as well is properly set VTP server and have the second side linked to it as client mode. ensured that keepalive settings are set to match each other. and removed native vlan. but main issue was a layer 1 issue.

Kind Regards,

Abdulla Sharaf