Ping loss on specific vlan when specific interface is bounced

[yum3372]

Weird symptom...

I have some switches in my network. and this weird symptom came to me last week. specific vlan(1145) is in my network and I can ping any of IP in that vlan normaly. but when if I bounce a specific interface on my 9300 switch, then I cannot ping any of IP in that vlan for a while (5-6sec), and then it goes well again. seems like broadcast storm? I don't know. the specific interface is for another switch in my network and they are configured as below. They are connected in access mode(VLAN1145), when I shutdown the Gi1/0/24 then I can ping any of IP in that vlan, but when I no shutdown the Gi1/0/24, then I cannot ping any of IP in that vlan for a while. any of IP is connected to many different switches, it's not related to the downlink switch, but It doesn't work for a while.

-----uplink switch-------------

interface GigabitEthernet1/0/24
switchport access vlan 1145
switchport mode access
storm-control broadcast level 20.00
storm-control multicast level 20.00
spanning-tree link-type point-to-point
end

--------downlink switch----------------

interface FastEthernet1/14
switchport access vlan 1145
switchport mode access
load-interval 30
macro description switch-automation
alarm profile ab-alarm
spanning-tree link-type point-to-point

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

[M02@rt37]

Hello @yum3372 

Please test without strom control commands.

[yum3372]

just tested without storm control. same symptom...

interface GigabitEthernet1/0/24
switchport access vlan 1145
switchport mode access
spanning-tree link-type point-to-point

[Joshqun Ismayilov]

Hello @yum3372 

Check interface statistic 

show interfaces GigabitEthernet1/0/24 | include input|broadcast
show interfaces counters errors

Thanks !

[yum3372]

here is the output.

input flow-control is on, output flow-control is unsupported
Last input 00:00:00, output 00:00:01, output hang never
5 minute input rate 736000 bits/sec, 239 packets/sec
1057020628 packets input, 165003408729 bytes, 0 no buffer
Received 849711850 broadcasts (849236663 multicasts)
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
0 watchdog, 849236663 multicast, 0 pause input
0 input packets with dribble condition detected
Output 13447895 broadcasts (4066490 multicasts)

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

Port Align-Err FCS-Err Xmit-Err Rcv-Err UnderSize OutDiscards
Gi1/0/1 0 0 0 0 0 0
Gi1/0/2 0 0 0 0 0 0
Gi1/0/3 0 0 0 0 0 0
Gi1/0/4 0 0 0 0 0 0
Gi1/0/5 0 0 0 0 0 0
Gi1/0/6 0 0 0 0 0 0
Gi1/0/7 0 0 0 0 0 0
Gi1/0/8 0 0 0 0 0 0
Gi1/0/9 0 0 0 0 0 0
Gi1/0/10 0 0 0 0 0 0
Gi1/0/11 0 0 0 0 0 0
Gi1/0/12 0 0 0 0 0 0
Gi1/0/13 0 0 0 0 0 0
Gi1/0/14 0 0 0 0 0 0
Gi1/0/15 0 0 0 0 0 0
Gi1/0/16 0 0 0 0 0 0
Gi1/0/17 0 0 0 0 0 0
Gi1/0/18 0 0 0 0 0 0
Gi1/0/19 0 0 0 0 0 0
Gi1/0/20 0 0 0 0 0 0
Gi1/0/21 0 0 0 0 0 190
Gi1/0/22 0 0 0 0 0 0
Gi1/0/23 0 0 0 0 0 0
Gi1/0/24 0 0 0 0 0 3916
Te1/1/1 0 0 0 0 0 0
Te1/1/2 0 0 0 0 0 0
Te1/1/3 0 0 0 0 0 0
Te1/1/4 0 0 0 0 0 0
Ap1/0/1 0 0 0 0 0 0
Po1 0 0 0 0 0 0

Port Single-Col Multi-Col Late-Col Excess-Col Carri-Sen Runts
Gi1/0/1 0 0 0 0 0 0
Gi1/0/2 0 0 0 0 0 0
Gi1/0/3 0 0 0 0 0 0
Gi1/0/4 0 0 0 0 0 0
Gi1/0/5 0 0 0 0 0 0
Gi1/0/6 0 0 0 0 0 0
Gi1/0/7 0 0 0 0 0 0
Gi1/0/8 0 0 0 0 0 0
Gi1/0/9 0 0 0 0 0 0
Gi1/0/10 0 0 0 0 0 0
Gi1/0/11 0 0 0 0 0 0
Gi1/0/12 0 0 0 0 0 0
Gi1/0/13 0 0 0 0 0 0
Gi1/0/14 0 0 0 0 0 0
Gi1/0/15 0 0 0 0 0 0
Gi1/0/16 0 0 0 0 0 0
Gi1/0/17 0 0 0 0 0 0
Gi1/0/18 0 0 0 0 0 0
Gi1/0/19 0 0 0 0 0 0
Gi1/0/20 0 0 0 0 0 0
Gi1/0/21 0 0 0 0 0 0
Gi1/0/22 0 0 0 0 0 0
Gi1/0/23 0 0 0 0 0 0
Gi1/0/24 0 0 0 0 0 0
Te1/1/1 0 0 0 0 0 0
Te1/1/2 0 0 0 0 0 0
Te1/1/3 0 0 0 0 0 0
Te1/1/4 0 0 0 0 0 0
Ap1/0/1 0 0 0 0 0 0
Po1 0 0 0 0 0 0

Port OverSize
Gi1/0/1 0
Gi1/0/2 0

Port OverSize
Gi1/0/3 0
Gi1/0/4 0
Gi1/0/5 0
Gi1/0/6 0
Gi1/0/7 0
Gi1/0/8 0
Gi1/0/9 0
Gi1/0/10 0
Gi1/0/11 0
Gi1/0/12 0
Gi1/0/13 0
Gi1/0/14 0
Gi1/0/15 0
Gi1/0/16 0
Gi1/0/17 0
Gi1/0/18 0
Gi1/0/19 0
Gi1/0/20 0
Gi1/0/21 0
Gi1/0/22 0
Gi1/0/23 0
Gi1/0/24 0
Te1/1/1 0
Te1/1/2 0
Te1/1/3 0
Te1/1/4 0
Ap1/0/1 0
Po1 0

[paul driver · Accepted solution]

Hello

---

@yum3372 wrote:
but when if I bounce a specific interface on my 9300 switch, then I cannot ping any of IP in that vlan for a while (5-6sec), and then it goes well again. seems like broadcast storm? I don't know. the specific interface is for another switch in my network 

They are connected in access mode(VLAN1145), when I shutdown the Gi1/0/24 then I can ping any of IP in that vlan, but when I no shutdown the Gi1/0/24, then I cannot ping any of IP in that vlan for a while. any of IP is connected to many different switches, 

---

Most possibly due to spanning-tee convergence  and given the point-to-point link type configured which suggest your running RPVST so 6 seconds (3x 2 sec hellos) would be about right for convergence of a designated switchport

Note: you can negate this by specifying that access port as a stp edge port, thus bypassing the renegotiation of spanning-tree stp which would put that port straight into a forwarding state but I wouldn't advise it as its a port that connects to another switch

[yum3372]

But.. Why the whole vlan is affected? few clients are connected to the downlink switch, but any of IP in that vlan would be affected. any of IP is connected to other switches. I don't think there's a reason why they are affected... Am I wrong?

Thanks for the mention anyway.

[paul driver]

Hello
I do not know your topology  but ALL designated switch-ports (non-stp edge ports) will be affected intpath towards root switch when you have a stp convergence.

That why ii is best to place all edge ports into portfast-edge mode and all non edge switchports (which are usually switch interconnects trunks) into a point-to-point stp link type   

[yum3372]

Cool. So can I add spanning tree portfast to each interface which is in access mode right? And will see how it goes.

[paul driver]

Hello
yes you can and its recommended to do so but as I have stated  ONLY on ports that are really only access ports meaning ports that usually have just a single host attached to them and NOT another switch

However in your OP you state to have switches attached to access ports (at the present with no portfast) so hence the stp convergence!

Now as these ports are being extended to attach switches that would then be only running for single vlan but its still another switch so i would be cautious of enabling PF on that switchport even if all the hosts in that other switch are all in the same vlan, but doing so WILL negate your "weird symptom "