Interface Line Protocol Flapping withtin LACP/Pagp Etherchannel
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06-13-2022 09:45 AM
Hello there,
suddenly some TenGigabitEthernet interfaces on an uplink of an access switch (C9200l-48P-4X ver. 17.3.4b) begin to flap, which means that the line protocol goes down and up again after approx. 2 seconds. The uplink leads towards an distrubition router (C9500). Those interfaces operate in an etherchannel of 2 links.
When removing interfaces from the etherchannel and let them operate as standalone, the flapping stops immediately. Thats why I would exclude a layer 1 problem like a faulty patch cable, bad gbic etc....
We have almost no input errors/CRC on counted on the concerning interfaces.
The log does not give any more information about possible causes:
021047: Jun 7 09:13:14 CEST: %LINEPROTO-5-UPDOWN: Line protocol on Interface TenGigabitEthernet1/0/19, changed state to down
021048: Jun 7 09:13:16 CEST: %LINEPROTO-5-UPDOWN: Line protocol on Interface TenGigabitEthernet1/0/19, changed state to up
021049: Jun 7 09:13:56 CEST: %LINEPROTO-5-UPDOWN: Line protocol on Interface TenGigabitEthernet1/0/19, changed state to down
021050: Jun 7 09:13:57 CEST: %LINEPROTO-5-UPDOWN: Line protocol on Interface TenGigabitEthernet1/0/19, changed state to up
I would be thankful for every help.
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Optical Networking
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06-13-2022 10:04 AM
- Can you check logs on the distribution router too. Also check interface counters, CRC on that device equally.
M.
-- Each morning when I wake up and look into the mirror I always say ' Why am I so brilliant ? '
When the mirror will then always repond to me with ' The only thing that exceeds your brilliance is your beauty! '
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06-13-2022 10:08 AM
Logs on the distri router are equal to the ones on the access switch. Just a flapping line protocol on the interfaces.
About 100 input errors a day can be find on the interfaces, which should not cause the links to go down.
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06-13-2022 11:44 PM
- Could you try changing , or use another then the current or default load balancing algorithm for lacp , check if that can help.
M.
-- Each morning when I wake up and look into the mirror I always say ' Why am I so brilliant ? '
When the mirror will then always repond to me with ' The only thing that exceeds your brilliance is your beauty! '
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06-13-2022 10:18 AM
check the show interface status,
when it down do you see err-disable ?
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06-13-2022 10:29 AM
The Interfaces does not become err-disabeld, only line protocol gets down and after 2 seconds up again.
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06-13-2022 10:46 AM
there are two end of the port channel, both end check
show interface status
check the err-disable,
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06-13-2022 10:40 AM
Hi
Logs does not say much about the problem. What I suggest is for you enable debug on the 9200 side with the command:
debug lacp all
debug pagp all
Hopefully this can give more information about the problem.
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06-13-2022 10:46 AM
is this stack ? what is the other side error ?
Can you post configuration both the sides ?
show run interface port-chan X
show run interface x/x
show interface x/x
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06-14-2022 12:26 AM
interface Port-channel4
switchport trunk native vlan x
switchport trunk allowed vlan x-y
switchport mode trunk
switchport nonegotiate
Interface of Access Switch:
switchport trunk native vlan x
switchport trunk allowed vlan x-y
switchport mode trunk
switchport nonegotiate
auto qos trust dscp
channel-group 6 mode active
service-policy input AutoQos-4.0-Trust-Dscp-Input-Policy
service-policy output AutoQos-4.0-Output-Policy
Interface of Distribution Router:
switchport trunk native vlan x
switchport trunk allowed vlan x-y
switchport mode trunk
switchport nonegotiate
auto qos trust dscp
channel-group 6 mode active
service-policy input AutoQos-4.0-Trust-Dscp-Input-Policy
service-policy output AutoQos-4.0-Output-Policy
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06-14-2022 02:24 AM
- Does the problem persist when the QoS-related commands are not used ?
M.
-- Each morning when I wake up and look into the mirror I always say ' Why am I so brilliant ? '
When the mirror will then always repond to me with ' The only thing that exceeds your brilliance is your beauty! '
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06-14-2022 06:11 AM
I removed the qos-related commands. Lets see if something changes
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06-14-2022 07:53 AM - edited 06-14-2022 07:54 AM
Line Protocol is still flapping, i removed the qos statements from the portchannel and the physical interfaces.
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06-14-2022 08:47 AM
- Could you try changing , or use another then the current or default load balancing algorithm for lacp , check if that can help.
M.
-- Each morning when I wake up and look into the mirror I always say ' Why am I so brilliant ? '
When the mirror will then always repond to me with ' The only thing that exceeds your brilliance is your beauty! '
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06-15-2022 04:44 AM
Unfortunately i does not help. I have choosen src-dst-ip as load balancing mechanism for the portchannel.
