Subject: Re: Linux was: Mbone Apps on.....

From: "Blaise Thauvin" <[email-masked]>
Date: Fri, 31 Oct 97 12:20:51 GMT

From: Malcolm Beattie <[email-masked]>, on 31/10/97 10:16:

>I'd therefore like to ask those on the list with first-hand experience
>of mrouted and kernel multicast routing the two questions about
>Linux/multicast which I haven't found good answers to yet:

Here I am -)

>(1) Is the claim about pruning made above true for current kernels
>(2.0.31) or was it a bug which (if it existed) has now been fixed?

The problem with pruning was a bug in older kernels. I faced it. 
It is now corrected, as my system now works while it wasn't.

The bug was in 2.0.11
It is not in 2.1.53

I think it was still in 2.0.30 as I have a old contribution from this list 
containing a patch to apply to 2.0.30 to make it work. The author claimed 
he expected is suggestions to be included in 2.0.31 or 32. Anyway, it has 
been applied immediatly in the Beta kernels (2.1.x)
I have not checked with 2.0.31 to see if it works.

>(2) Another rumour on this list is that mrouted under Linux has
>problems tunnelling out to other hosts. Is that true? I currently have
>Linux mrouted running as a leaf node but I'll be setting up tunnels to
>others soon. As far as I'm aware, no outstanding Linux kernel multicast
>bugs have shown up in the developers mailing list for a long time.
>Possibly that's because there really aren't any, because the main
>developers haven't mentioned them to the list or because nobody has
>given any bug reports. If it's either of the latter two cases, I'd like
>to see detailed bug reports here and I'll either forward them to the
>relevant lists/people and/or try to fix them myself.

The tunneling problem was linked to the prunning problem. As soon as you 
would set up a tunnel, your entire bandwith would be used as all groups 
would be forwarded through the tunnel, either requested or not. without 
prunning, the load would never decrease.

I have now three Linux boxes running mrouted. One is my link to the outside 
world, using a tunnel. It tunnels again to a second machine located on one 
of our inside networks. The third one is running mrouted but no tunnels. It 
routes between three physical networks. This is to have a setup with almost 
all possible configurations available.

The clients are either PCs on the said physical networks or applications on 
any of the Linux boxes. It runs perfectly on all of them. My prefered MBone 
workstation is the Linux box between the three nets. It is only a 486/50 
running XWindows, but performance is far better than on my Pentium PC 
running Win95 with more memory.

Blaise

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