Do you care about "gray" failures? Can we (network academics) help? A 10-min survey

Chriztoffer Hansen ch at
Fri Jul 9 07:52:22 UTC 2021

On Thu, 8 Jul 2021 at 22:10, Baldur Norddahl <baldur.norddahl at> wrote:
> We had a line card that would drop any IPv6 packet with bit #65 in the destination address set to 1. Turns out that only a few hosts have this bit set to 1 in the address, so nobody noticed until some Debian mirrors started to become unreachable. Also, web browsers are very good at switching to IPv4 in case of IPv6 timeouts, so nobody would notice web hosts with the problem. And then we had to live with the problem for a while because the device was out of warranty and marked to be replaced, but you do not just replace a router in a hurry unless you absolutely need to.

Grey failures, ugh. Heard of a colleague at prior employment who did
troubleshooting of an issue with an extended line. Where packets to
select IPv4 dest addresses would be dropped by the extended line card.
Took time plus inserting middle-boxes from Vendor Y (packet capture
for evidence) to confirm and convince the vendor of their code had
problems. 😫

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