From lists+aristansp at bensley.me  Mon Jun 22 11:58:11 2026
From: lists+aristansp at bensley.me (James Bensley)
Date: Mon, 22 Jun 2026 15:58:11 +0000
Subject: [a-nsp] Testing forwarding lookups
Message-ID: <MvbSYJEL7rUUB9IqoB0xk2Ns9nMphkyiG_k8-aryYn8l2hkRbeZezK0izYDmE1F_6cabDMgDSukjzp3E4mHl-OQSUiohGVpAwwBl_q2v3vY=@bensley.me>

Hi all,

There was a thread on NANOG a while back discussing the equivalent command across different vendors, to check what the device would do if a specific packet came in to a specific port [1].

I commented back then there was no way to do this on Jericho2/+/2C boxes with Arista EOS (I'm talking about the 7280R3 range).

After some time reverse engineering the Broadcom debugging tools I've got it working now. I've written up my notes for a version 1.0 here: https://null.53bits.co.uk/index.php?page=7280r3-diag-packet-tx

I'm sure it can be improved upon but that's all I've got time for right now. Hope that helps someone else.

Cheers,
James.


[1] https://lists.nanog.org/archives/list/nanog at lists.nanog.org/thread/65IZUIUM3WTM56W3CLM6HOGK2T7DCEKF/#YB5IW53XGT2HUCIETTTJER6T23TAPTGI
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From bryan at shout.net  Thu Jun 25 06:05:16 2026
From: bryan at shout.net (Bryan Holloway)
Date: Thu, 25 Jun 2026 12:05:16 +0200
Subject: [a-nsp] Testing forwarding lookups
In-Reply-To: <MvbSYJEL7rUUB9IqoB0xk2Ns9nMphkyiG_k8-aryYn8l2hkRbeZezK0izYDmE1F_6cabDMgDSukjzp3E4mHl-OQSUiohGVpAwwBl_q2v3vY=@bensley.me>
References: <MvbSYJEL7rUUB9IqoB0xk2Ns9nMphkyiG_k8-aryYn8l2hkRbeZezK0izYDmE1F_6cabDMgDSukjzp3E4mHl-OQSUiohGVpAwwBl_q2v3vY=@bensley.me>
Message-ID: <5ae9d6cf-09f7-45d4-a223-790b5e8c3850@shout.net>

This is really cool ... thank you for sharing!


On 6/22/26 17:58, James Bensley via arista-nsp wrote:
> Hi all,
> 
> There was a thread on NANOG a while back discussing the equivalent command across different vendors, to check what the device would do if a specific packet came in to a specific port [1].
> 
> I commented back then there was no way to do this on Jericho2/+/2C boxes with Arista EOS (I'm talking about the 7280R3 range).
> 
> After some time reverse engineering the Broadcom debugging tools I've got it working now. I've written up my notes for a version 1.0 here: https://null.53bits.co.uk/index.php?page=7280r3-diag-packet-tx
> 
> I'm sure it can be improved upon but that's all I've got time for right now. Hope that helps someone else.
> 
> Cheers,
> James.
> 
> 
> [1] https://lists.nanog.org/archives/list/nanog at lists.nanog.org/thread/65IZUIUM3WTM56W3CLM6HOGK2T7DCEKF/#YB5IW53XGT2HUCIETTTJER6T23TAPTGI
> 
> 

