Forwarding issues related to MACs starting with a 4 or a 6 (Was: [c-nsp] Wierd MPLS/VPLS issue)

Simon Lockhart simon at
Fri Dec 2 16:02:43 UTC 2016

On Fri Dec 02, 2016 at 10:29:56AM -0500, Christopher Morrow wrote:
> you'd think standard testing of traffic through the asic path somewhere
> between 'let's design an asic!' and 'here's your board ms customer!'  would
> have found this sort of thing, no? or does testing only use 1 mac address
> ever?

Well, it's actually payload, rather than src/dst MAC used for forwarding, so
there's quite a few more combinations to look for...

2^(8*9216) is quite a lot of different packets to test through the forwarding
path... But, wait, that assumes every bit combination for 9216 byte packets,
but the packet might be shorter than that... So multiply that by (9216-64).

Anyone want to work out how many years that'd take to test, even at 100G?


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