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Re: ip6_output(): routing link local addresses



Edgar Fuß <ef%math.uni-bonn.de@localhost> writes:

>> but: why should there be?
> Because you need to take the scope into account.

(From memory, fuzzy.)

Link-local addresses look like

fe80::stuff

when sent *on the link*.  However, such an address used not on a link
does not obviously correspond to any particular link.

So, you see something like

fe80::stuff%fxp0

when printed, and this is doing some magic stuffing the ifindex byte for
fxp0 in a byte in the address (low byte of the top half?) that is
otherwise must-be-zero.  This is how it's in the routing table, and the
addresses are munged on the way out/in so they are in this form for
applications and in standard form on the wire.

I probably misremember somewhat, but this is highly likely a useful
clue.

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