[Olsr-dev] why adding mac address in hello-msg

Ferry Huberts (spam-protected)
Mon Oct 12 09:36:48 CEST 2015



On 12/10/15 07:47, work_xl wrote:
> I know the mac Bytes cost only a little for wifi.But I am working on a
> network in which some channels are so bad ,every Byte is important.I
> will try to set a constant metric for these channels and test the
> performance.
>

If you can't spare 6 bytes in such a message then maybe you shouldn't 
run a mesh protocol over it. You should at least think very hard about 
it :-)

>
>
> On 2015-10-11 21:03 , Henning Rogge <mailto:(spam-protected)> Wrote:
>
>     What metric do you plan to use?
>
>     the MAC tlv is not that much overhead because its only in the Hello
>     messages, which are not flooded through the network.
>
>     Henning
>
>     P.S.: please reply to the mailing list if possible so that other
>     people can learn from your experience and handling of the software.
>
>     On Sun, Oct 11, 2015 at 2:45 PM, work_xl <(spam-protected)> wrote:
>      > Thank you for your instruction.Now I can understand your
>     "beautiful"mac
>      > hack. I would not use DATmetric.So I will just cut this mac bytes
>     for lower
>      > radio channel cost and see what's going to happen.
>      >
>      >
>      > On 2015-10-10 18:08 , Henning Rogge Wrote:
>      >
>      > Hi,
>      >
>      > very nice to see someone noticed this "slightly ugly hack".
>      >
>      > The DAT metric I use for NHDP/OLSRv2 uses linklayer information
>     to get
>      > the incoming datarate for each neighbor... unfortunately the nl80211
>      > subsystem (of course) does only know the MAC address of the
>     neighbors,
>      > so I need a way to know which MAC address corresponds to which NHDP
>      > neighbor (which I know via IP address).
>      >
>      > The joke is that while every incoming (linklocal) multicast from the
>      > neighbors contains the MAC address in the ethernet header, there
>     is no
>      > way in Linux to get the MAC address of an incoming UDP packet except
>      > for using a raw socket... which are a headache to use with multicast
>      > (e.g. creating the necessary IGMP/ICMPv6 multicast join/leave
>      > messages).
>      >
>      > I still hope there is a better way to do this, but until someone
>      > suggest one I just added the MAC address to each NHDP HELLO
>     message as
>      > an easy way to get the MAC address of the other sides interface.
>      >
>      > Henning
>      >
>      > On Sat, Oct 10, 2015 at 5:26 AM, work_xl <(spam-protected)> wrote:
>      >> Hi,
>      >> In nhdp plugin code,there is a msg tlv named
>     NHDP_MSGTLV_MAC.Writer write
>      >> it
>      >> and reader read it.But I could not find it in both rfc6130 and
>     rfc7181.On
>      >> the other hand,I did not realize its function in the codes
>     .So,why do we
>      >> add
>      >> this tlv?What could happen if I just remove it?
>      >> Best regards.
>      >>
>      >> xl
>      >>
>      >> --
>      >> Olsr-dev mailing list
>      >> (spam-protected)
>      >> https://lists.olsr.org/mailman/listinfo/olsr-dev
>     Q
>
>
>

-- 
Ferry Huberts



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