Re: Forwarding Packets With Link Local Destination Addresses

Alexandre Petrescu <alexandre.petrescu@gmail.com> Thu, 07 January 2021 18:59 UTC

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Subject: Re: Forwarding Packets With Link Local Destination Addresses
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From: Alexandre Petrescu <alexandre.petrescu@gmail.com>
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Le 07/01/2021 à 18:53, Ron Bonica a écrit :
> Folks,
> 
> According to RFC 4291, “routers must not forward any packets with 
> Link-Local source or destination addresses to other links”.
> 
> I interpret this statement to include packets that contain routing 
> headers. For example, it forbids an SRv6 packet whose final segment has 
> a locator that begins with FE80.

It's easy to say that 'it begins with fe80' but that is hard to 
implement unless the programmer knows precisely the prefix length.

Some might implement it with a /64 plen, others with a /10 plen, 
depending on which RFC and IANA table one looks at more trustfully.

If one takes literally 'begins with fe80' then it would be a /16, but 
probably that is less likely to be considered seriously.

It might be a problem more of basic link-local address format, and 
probably also of a SRv6 interest.

Alex

> 
> Does everyone share this interpretation? If so, do RFC 4291 or RFC 8200 
> make this sufficiently clear?
> 
>                                         
>                                                              Ron
> 
> 
> Juniper Business Use Only
> 
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