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


From: Saku Ytti <saku () ytti fi>
Date: Sat, 3 Dec 2016 01:17:48 +0200

On 2 December 2016 at 18:16, Alia Atlas <akatlas () gmail com> wrote:
This sounds related to the well-known (at least 10+ years) issues around
guessing the
type of IP packet by looking at the first nibble of the encapsulated packet.
Take a quick look at RFC 7325, section 2.4.5.1 bullet 6.
This is what using the pseudo-wire code-word is meant to protect against.

I don't know if that's an option for networks using this.

Some devices by default look inside pseudowires to find IP inside
them, in this case even control-word won't help, you'll need to also
disable looking inside pseudowire.


-- 
  ++ytti


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