Subject: Re: linux multicast ...

From: "Wilfried Woeber, UniVie/ACOnet" <[email-masked]>
Date: Thu, 15 May 1997 19:08:12 MET-DST

Hi Magnus!

>... However, for larger private
>networks there is a need to allow routing of the private addresses so
>one needs to be able to make the restriction at the border between
>private and global addresses. Now, I don't beleive that this is a hard
>thing to implement, but until it is we will continue to see private
>addresses being announced on Mbone.

  I'm sorry, but I have to disagree and to spaek up about that.
  Private address space is named private address space becasue it is
  supposed to address interfaces in a private environment. And I'm sure
  you are aware of that :-)

>In order to let a machine in the private address space to source
>trafic must the multicast router act in a IP Masquerading fasion. This
>is not really in mrouteds scope but it can still be done there. This
>have ofcourse limits, but it may be a compromise worth considering.

  I think even putting that up for discussion is already a bad idea.

  I think we do indeed have enough routing problems already, both in the
  unicast as well as in the multicast world.
  
  Adding just another level of complexity, e.g. a NAT for multicast only,
  might give us that last push that is needed while standing at the brink
  of ...
  
  I'd rather find out how to properly filter/block RFC1918 addresses in
  the DVMRP world?!

  Wilfried.
 --------------------------------------------------------------------------
  Wilfried Woeber                :  e-mail: [email-masked]
  Computer Center - ACOnet       :  
  Vienna University              :  Tel: +43 1 4065822 355
  Universitaetsstrasse 7         :  Fax: +43 1 4065822 170
  A-1010 Vienna, Austria, Europe :  NIC: WW144
 --------------------------------------------------------------------------

---

From: Magnus Danielson <[email-masked]>
Date: Thu, 15 May 1997 19:36:42 +0200

>>>>> "WWU" == Wilfried Woeber, UniVie/ACOnet <[email-masked]> writes:

 WWU>   Hi Magnus!
 >> addresses being announced on Mbone.

 WWU>   I'm sorry, but I have to disagree and to spaek up about that.
 WWU>   Private address space is named private address space becasue it is
 WWU>   supposed to address interfaces in a private environment. And I'm sure
 WWU>   you are aware of that :-)

Yes.

But today I see how for instance 193.168 addresses do gets global
multicast routing. If people want a multicast stream in such networks
from external Mbone we could at least ensure that the outside world
does not suffer more than the pure network load of the requested
stream.

I agree that the hole 193.168 buissness is a kludge, I tried to point
out some methods which could hide the kludge rather than spread it.

 >> have ofcourse limits, but it may be a compromise worth considering.

 WWU>   I think even putting that up for discussion is already a bad idea.

You may be very right. But I wanted an intellectual discussion
wheither it was feasable to do or not.

 WWU>   I think we do indeed have enough routing problems already, both in the
 WWU>   unicast as well as in the multicast world.
  
 WWU>   Adding just another level of complexity, e.g. a NAT for multicast only,
 WWU>   might give us that last push that is needed while standing at the brink
 WWU>   of ...

Hmm. Either we are talking about the same thing and I am missing some
very good point of yours or we are infact talking about diffrent
things and misses each others points.
  
 WWU>   I'd rather find out how to properly filter/block RFC1918 addresses in
 WWU>   the DVMRP world?!

Well, isn't this in a way what I first proposed?

Whatever I had in mind was certainly a local border gateway problem in
order to get multicast from the global world into hidden addresses
without letting the hole world suffer from their
announcments. Consider it as a firewall situation.

This was only an idea, an proposal... please discard with thougth if
it doesn't match the reallity well enougth.

Cheers,
Magnus