[192967] in North American Network Operators' Group
Re: Forwarding issues related to MACs starting with a 4 or a 6 (Was:
daemon@ATHENA.MIT.EDU (Mike Jones)
Tue Dec 6 07:51:21 2016
X-Original-To: nanog@nanog.org
In-Reply-To: <20161206122841.GA984@Vurt.local>
From: Mike Jones <mike@mikejones.in>
Date: Tue, 6 Dec 2016 12:50:38 +0000
To: nanog@nanog.org
Errors-To: nanog-bounces@nanog.org
> MACs that didnt make it through the switch when running 4.12.3.1:
>
> 4*:**:**:**:**:**
> 6*:**:**:**:**:**
> *4:**:**:**:**:**
> *6:**:**:**:**:**
> **:**:*B:**:6*:**
> **:**:*F:**:4*:**
Can anyone explain the last 2 for me?
I was under the impression that this bug was mainly caused by some
optimistic attempt to detect raw IPv4 or IPv6 payloads by checking for
a version at the start of the frame. This does not explain why it
would be looking at the 5th octet.
I also would assume that there must be something else to the last 2
examples beyond just the B or F and 4 or 6 because otherwise it would
match way too many addresses to have not been noticed before. Perhaps
the full MAC address looks like some other protocol with a 4 byte
header?
Thanks,
Mike
