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Forwarding issues related to MACs starting with a 4 or a 6 (Was: [c-nsp] Wierd MPLS/VPLS issue)
- Subject: Forwarding issues related to MACs starting with a 4 or a 6 (Was: [c-nsp] Wierd MPLS/VPLS issue)
- From: nick at foobar.org (Nick Hilliard)
- Date: Fri, 02 Dec 2016 16:59:37 +0000
- In-reply-to: <[email protected]>
- References: <[email protected]>
Job Snijders wrote:
> Dear IEEE, please pause assigning MAC addresses that start with a 4 or a
> 6 for the next 6 years.
Disagree that this is an IEEE problem. This is problem that vendors
need to work around. There is limited MAC space, and deprecating 1/8 of
it due to the inability of vendors to cope properly with it seems like a
really bad long term idea.
It seems that the problem that cropped up on cisco-nsp is that a layer 2
switch, the Nexus 92160 (and possibly everything else which uses the
same forwarding ASIC), cannot forward vpls frames with a 4 or 6 buried
at a specific location inside the contents of the frame.
This is an extraordinary bug which renders the hardware useless in
specific circumstances. What makes it worse is that this is a well
known corner case which should have been shaken out during design, if
not found during QA.