[c-nsp] Cisco Gigabit EthernetSwitch Module
(CGESM)fortheHPBladeSystem
christian.macnevin at uk.bnpparibas.com
christian.macnevin at uk.bnpparibas.com
Tue Oct 11 11:45:03 EDT 2005
Yup. It seems to me as though Cisco et al view multicast as the preserve
of the triple play providers.
The truth of the matter is, nobody uses multicast like the financials. And
yes, take that any way you please ;)
The guys I've met from Tibco view Cisco as the enemy of multicast, oddly
enough. Odd, because their
solution to everything is to upgrade the entire network to gig. To me,
this is counterintuitive, because it just
means multicast storms take longer to detect, and you offload the problem
from the network to the host - which
now may routinely be asked to cope with half a gig of multicast traffic,
most of which it actually needs to
discard at the application layer. But to Cisco, it should sound like a
sales opportunity!
Internet
dave at ordinaryworld.com
11/10/2005 16:33
To
Christian MACNEVIN
cc
Subject
Re: [c-nsp] Cisco Gigabit EthernetSwitch Module (CGESM)fortheHPBladeSystem
People don't understand the concept of TIBCO/RV and how it works. Until
they've seen it on a live network it's all conjecture. You make very
valid points and Cisco needs to address the financial community better in
terms of Multicast and remember that we've spent a lot more money on
multicast-related technology than probably all of the Internet combined
(which is the direction that most of their multicast technology is aimed).
-Dave
On Tue, 11 Oct 2005 christian.macnevin at uk.bnpparibas.com wrote:
> Ok, so I raise it to 110 Meg. So now all my sinks are getting 10 meg a
> second more than their ports
> can handle, so the port drops it, and the hosts NAK. Once again we have
a
> NAK implosion.
>
> Multicast reliability mechanisms experience traffic increases as a
> function of the number of nodes
> connected multiplied by the number of multicast group memberships under
> congested conditions.
> The second we start dropping traffic from a source - whatever the limit
is
> - everyone starts asking
> for it again, and if we start dropping some of the retransmisssions,
then
> wahey, race condition.
>
> Once again, if anyone out there has some experience with how this might
> evolve in a live environment,
> I'm really keen to hear it.
>
>
>
>
>
>
> Internet
> jtk at northwestern.edu
> Sent by: cisco-nsp-bounces at puck.nether.net
> 11/10/2005 15:34
>
> To
> cisco-nsp
> cc
>
> Subject
> Re: [c-nsp] Cisco Gigabit EthernetSwitch Module
> (CGESM)fortheHPBladeSystem
>
>
>
>
>
>
> On Tue, 11 Oct 2005 11:38:41 +0100
> christian.macnevin at uk.bnpparibas.com wrote:
>
> > So let's say you limit your machine to 10% of the total link bandwidth
> > as multicast, to force it down to 100Meg. Nice one.
> > Let's now say it tries to start sending 101 Meg. Your switch starts
> > dropping 1% of all packets. Which 1%? Who knows? So
> [...]
>
> Can't you just raise the limit to 10% plus some fudge for missed
> packets? Presumably you shouldn't need much of a fudge, otherwise
> it would seem worthwhile to first investigate why so so many might
> be getting dropped to begin with.
>
> John
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