Date: Mon, 03 Mar 2008 12:47:40 +0000 From: "Bruce M. Simpson" <bms@FreeBSD.org> To: Willem Jan Withagen <wjw@digiware.nl> Cc: =?ISO-8859-1?Q?=3Fukasz_Bromirski?= <lukasz@bromirski.net>, net@freebsd.org, Ingo Flaschberger <if@xip.at>, Barney Cordoba <barney_cordoba@yahoo.com> Subject: Re: FBSD 1GBit router? Message-ID: <47CBF36C.9000702@FreeBSD.org> In-Reply-To: <47CBF16C.6020704@digiware.nl> References: <alpine.LFD.1.00.0803012014350.20402@filebunker.xip.at> <497111.42659.qm@web63905.mail.re1.yahoo.com> <20080301225727.GA85851@owl.midgard.homeip.net> <47CAADB8.9000202@digiware.nl> <47CC304F.6040006@bromirski.net> <47CBF16C.6020704@digiware.nl>
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Willem Jan Withagen wrote:
> Łukasz Bromirski wrote:
>> Wouldn't it be a case for use of multicast vs unicast? Hardware
>> is always better anyway, so why not invest in some switch that
>> can do unicast/multicast in hardware?
>
> Usefull suggestion, only this is going to be in an overlay cloud where
> we do not have control over all the endpoint networks. let alone that we
> can get them to use multicast. And even those that use multicast in their
> last-mule equipment, don't always have correct setups.
>
> My experience is that Multicast in nice in theory and experiment, but
> when
> push comes to shove it does not completely deliver.
I have to agree wholeheartedly, for more detail than you can shake a
stick at, look here:
http://www.cs.ucr.edu/~michalis/COURSES/204-02b/papers/ramalho.html
If you're running over MPLS all bets are off. MPLS is like ATM in the
sense that it ain't got no multicast grok, as far as I can fathom,
anyway. Label switching is label switching. I never saw any support for
the notion of 1:M in the LSPs.
Multicast is more likely to succeed at the moment when you have complete
knowledge of the network topology, and IP layer visibility. There are
ongoing efforts to address these limitations.
later
BMS
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