[ECOS] IPv6 on synth over TAP interface

Bart Veer bartv@ecoscentric.com
Mon Mar 31 14:41:00 GMT 2003

>>>>> "Andrew" == Andrew Lunn <andrew.lunn@ascom.ch> writes:

    Andrew> Hi Folks
    Andrew> Has anybody tried running IPv6 on the synth target, using
    Andrew> the synth ethernet on a TAP device?

    Andrew> I've got IPv4 working properly, talking to a DHCP client
    Andrew> on my host machine etc. But with IPv6 i get lots of
    Andrew> warnings from eCos about multicast, and radvd spins
    Andrew> horribly.

    Andrew> Has anybody been there, done that, and written a HOWTO?

I don't remember trying IPv6 with the synthetic target, but can give
you some pointers.

IPv6 requires multicast support, i.e. it needs additional
functionality from the ethernet device driver.

With the ecosynth ethernet driver, ethernet I/O goes via the I/O
auxiliary to the rawether process on the host
(devs/eth/synth/ecosynth/current/host). That process can interact with
either a real ethernet card or with the tap device. Not all real
ethernet cards will support multicasts, so during initialization there
is a message from rawether to the eCos ecosynth driver containing a
multicast_supported flag (plus other info like the MAC address). The
eCos driver then uses that information when processing the SET_MC_ALL
ioctl(). IIRC the tap device should always support multicasts.

So in theory it should just work... :-)


Bart Veer                       eCos Configuration Architect
http://www.ecoscentric.com/     The eCos and RedBoot experts

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