[vlc-devel] Streaming wizard issues
jpd at videolan.org
jpd at videolan.org
Mon Nov 30 10:50:12 CET 2009
On Mon, Nov 30, 2009 at 10:15:06AM +0100, Marian ??urkovi?? wrote:
> 1) multicast doesn't get beyond a router which is not *explicitly*
> configured to route it. Any local network is effectively isolated by
> this even without TTL=1 hack
That's still no reason to set up this and the next network for instant
flooding the moment it does get enabled. If ``the user'' does that
knowingly, it is their doing. If the same user unwittingly does it
because we set the default unreasonably high, it is our doing.
> 2) problem with TTL=0 happens even on largest internet-grade routers like
> Cisco 7600, which are certainly well capable of routing multicast
Apparently not, but then it also was Cisco software that would duly
decrement-by-one-and-propagate packets incoming with TTY=0. A big name
is no guarantee of well-behavedness.
> 3) usage of TTL scoping is discouraged by latest RFCs, I don't have time
> to look it up ATM but courmisch can certainly provide a reference to you,
> since he already changed SAP announcer to *not* use TTL scoping quite some
> time ago. TTL scoping sucks big time, it shouldn't be used anymore.
Then at most default to the system-wide default. Do provide references
when you do have the time. But I think you are mixing up ``providing
a safe default'' and ``depening on TTY=N for your production use'' here.
For the latter, non-TTY means may very well be preferrable. But for
the former, in case of casual or ignorant over-reach, network fault
isolation benefits from predictability, and TTY=1 provides that, there
arbitrarly high TTY does not.
The default in VLC isn't ment for production, but to provide a sane
default, and in the case of multicast with its flooding potential,
limiting the damage to the local broadcast domain and its gateway(s) is
much more sane than flooding everywhere.
More information about the vlc-devel