Find VLAN Bad Packets

[CobbyJ]

Hello.

I have narrowed down an issue to something on a single vlan, it is sending a lot of pad packets all over our network and causing high MS on certain switches unless we remove that vlan.

Is there any recommendations on what we can use to try and find where these bad packets are coming from?

Kind Regards,

Chris

[lucasfreitas83]

Hello CobbyJ,

Please, share how to see these packets?

PAD packets cant use today, unless if you use X25 circuits.

"Short for packet assembler/disassembler PAD is a device (hardware or software) used in packet switching to enable data terminal equipment (DTE) not equipped for packet switching to access a packet-switched network. PAD is a term most often associated with an X.25 network where the PAD breaks the data stream into individual packets and formats the packet headers for asynchronous transmission."

If you do not use this, disable globally in all switches.

no service pad

Please rate and mark posts accordingly if you have found any of the information provided useful.
It will hopefully assist others with similar issues in the future.

Best regards,
Lucas Freitas

[Mark Malone]

You could use wireshark , span the vlan traffic

[CobbyJ]

That wont work because its going over switch to switch on a trunked vlan, i need a cisco command to find where its coming from.

ARP wont work as its trunked traffic.

[Mark Malone]

you can capture trunk traffic too using wireshark , it can capture everything when setup correctly,if your looking for the specific platform/asic commands to see something like that you will need TAC , its a lot more difficult to track issues like that using cli , your better off using a software tool

[lucasfreitas83]

Hello,

Depend on your device you can use monitor capture to capture packets directly on the device, but Wireshark is easier.

https://www.cisco.com/c/en/us/support/docs/ios-nx-os-software/ios-embedded-packet-capture/116045-productconfig-epc-00.html

Do you try to disable service PAD?

Please rate and mark posts accordingly if you have found any of the information provided useful.
It will hopefully assist others with similar issues in the future.

Best regards,
Lucas Freitas