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flow-control

‎05-19-2020 05:15 PM

Hi all

It is happening on mx...Any idea?

fpc4 Prolonged flow-control asserted by MAC on ms-4/3, bringing interface down

(FPC Slot 4, PIC Slot 3) ms43 kernel: WARNING: preposterous time in file system
(FPC Slot 4, PIC Slot 3) ms43 kernel: WARNING: No TOD clock, believing file system.

7 REPLIES 7
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Re: flow-control

‎05-19-2020 05:54 PM

Hi, open JTAC case if you want know the reason, or just reboot this NPU to restore service

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Re: flow-control

‎05-19-2020 06:04 PM

What is NPU ?

searched kb and pr, couldn't find particular things...

also checked chassid before and after time that card went off. Some logs on chassisd says the following.... 8 and 7 are not correct that Junos generated on the device because no one touched the device.

jnxFruOfflineReason 8----->>>>pressbutton

jnxFruOfflineReason 7------>>>>clicommand

jnxFruOfflineReason 2 ------->>>none

 

https://kb.juniper.net/InfoCenter/index?page=content&id=KB29446&actp=search&viewlocale=en_US&searchi...

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Re: flow-control

‎05-19-2020 06:21 PM

Hi Arix,

 

Packet-based, or stateless, packet processing treats packets discretely. Each packet is assessed individually for treatment. For the distributed processing architecture of the services gateway, some packet-based processing, such as traffic shaping, occurs on the NPU.

 

To know the FRU offline reason we might need the logs from messages and chassis files. So, it will be best if you open a JTAC case for a thorough analysis of this.

 

Hope this helps 🙂

 

Please mark "Accepted Solution" if this helps.

Kudos are always appreciated

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Re: flow-control

‎05-19-2020 06:31 PM

 Arix,

 

Adding more details:

The Network Processing Unit (NPU) and the Network Processing session

An NPU is a processor that runs on an I/O card (IOC) and processes packets discretely. When a flow is created, subsequent packets of the flow are matched to the session on the NPU. The NPU handles additional processing such as TCP sequence check, time-to-live (TTL) processing, and Layer 2 header translation. An NPU improves performance in that extra packet forwarding between a session-SPU and a hash-SPU is avoided. The SRX4600 Services Gateway implements an NPU.

 

You can refer the below link which has details about NPU and where all it could be useful and what functions it does:

https://www.juniper.net/documentation/en_US/junos/topics/topic-map/security-srx-devices-processing-o...

 

Hope this helps 🙂

 

Please mark "Accepted Solution" if this works for you.

Kudos are always appreciated.

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Re: flow-control

[ Edited ]
‎05-19-2020 07:02 PM

Thanks reply...

 

How to reboot this NPU on mx router in operation and what is the impact? 

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Re: flow-control

‎05-19-2020 07:43 PM

Hello Arix,

 

Greetings!

 

To reboot the whole FPC:

 

>request chassis fpc offline slot 4

 

After 2 minutes

 

>request chassis fpc online slot 4

 

To reboot the specific PIC on the FPC: 

 

>request chassis pic pic-slot 3 fpc-slot 4 offline

 

After 2 minutes

>request chassis pic pic-slot 3 fpc-slot 4 online

 

Yes, there will be an impact on the services running on the particular FPC as it will reboot.

 

Make sure you perform this on a safe Maintenance window or shift the traffic to other FPC and reboot the FPC 4.

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

 

Regarding the Log messages:

 

(FPC Slot 4, PIC Slot 3) ms43 kernel: WARNING: preposterous time in file system
(FPC Slot 4, PIC Slot 3) ms43 kernel: WARNING: No TOD clock, believing file system.

 

These messages say that the MS MIC unable to communicate to master RE. To know the detailed reason, you need to open a JTAC ticket.

 

If the FPC reboot didn't resolve the issue, you need to restart the master RE in a safe Maintenance window to restore services.

 

I hope this helps. Please mark this post "Accept as solution" if this answers your query.

 

Kudos are always appreciated! Smiley Happy

 

Best Regards,

Lingabasappa H

 

 

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Re: flow-control

‎05-19-2020 08:04 PM

Hello,

 

MS-MPC typically asserts flow-control when its rated parameters such as flow setup rate, or PPS rate are exceeded.

Please add following lines into Your config:

 

 

set interfaces pc-4/0/0 multiservice-options flow-control-options reset-on-flow-control
set interfaces pc-4/0/0 multiservice-options flow-control-options dump-on-flow-control 
set interfaces pc-4/1/0 multiservice-options flow-control-options reset-on-flow-control
set interfaces pc-4/1/0 multiservice-options flow-control-options dump-on-flow-control
set interfaces pc-4/2/0 multiservice-options flow-control-options reset-on-flow-control
set interfaces pc-4/2/0 multiservice-options flow-control-options dump-on-flow-control
set interfaces pc-4/3/0 multiservice-options flow-control-options reset-on-flow-control
set interfaces pc-4/3/0 multiservice-options flow-control-options dump-on-flow-control

 

 

 

Next time when MS-MPC PIC experiences flow-control, it will automatically reset and generate core-dump.

And then please open a JTAC case and submit this core-dump for analysis.

To mitigate traffic loss during MS-MPC PIC reset event, use AMS bundle interfaces

https://www.juniper.net/documentation/en_US/junos/topics/concept/ams-understanding.html

https://www.juniper.net/documentation/en_US/junos/topics/example/ams-configuring.html

HTH

Thx

Alex 

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