All things related to multicast

["Timothy P Shortall" <>]

Christian,

I haven't followed this thread, so I'll just share an experience and if it
helps that's great.

Three years ago I was supporting a large network and noticed the MRTG/CPU
graphs were spiking on two of the distribution routers during the night at
various times.  After some analysis we narrowed it down to a subnet that we
did not manage and because of the times suggested that they look at their
Ghosting operation.  We inquired if their server was set up for multicast
and they said it was.  Long story short - the contractor had configured the
Ghosting to use broadcast.  The server was connected to a 100Mb access port
and peaked at 70Mb during the ghosting.  That 70Mb cause two 6513 DRs with
Sup720s to spike their CPUs to 99%.  Once they reconfigured their Ghost
server to use multicast the problem was resolved.

Tim Shortall
University of Maryland at College Park

-----Original Message-----
From: Marshall Eubanks 
[mailto:]
 
Sent: Wednesday, September 26, 2007 2:52 PM
To: 

Cc: 

Subject: Re: Norton Ghost with multicast

Could you be receiving Norton Ghost transmissions from outside your  
network ?

They should be filtered out but are not always.

Regards
Marshall

On Sep 26, 2007, at 2:45 PM, 
<>
 wrote:

> Hello !
>
>             We use a lot of multicast on the LAN. The throughputs  
> of multicast traffics seem to vary a lot during the day and ghost  
> operation are not reliable on the LAN.  We use Catalyst 6500 with  
> Sup720  PIM- Sparce-dense mode. During the day, Cpu, memory and  
> link utilization doesn’t seem to be busy enough to affect  
> performance.  At night Ghost are very fast so the problem point to  
> my switch.  Maybe I am not monitoring the right variable on my  
> Catalyst 6500 to link this performance issue with a certain  
> chokepoint in my Catalyst.
>
>
>
>             Many CCIE came to solve our multicast/Ghost problem but  
> nobody ever succeeded. If anybody can suggest item I might have  
> overlook or I should investigate let me know off line. We have  
> validated the configuration with auto-RP and pim-sparce-dense mode.
>
>
>
> Thanks,
>
>
>
> Christian Héroux
>
> Bacc Ing. ÉTS, M. Ing. Poly, étudiant MBA HEC, Ing jr.
>
>
>
> Analyste de l'informatique
>
> (Sécurité réseau & Télécom)
>
> Section systèmes, infrastructures et télécommunications
>
> École de Technologie Supérieure
>
> 1100 rue Notre-Dame ouest
>
> Montréal, Québec
>
> H3C 1K3
>
> Tél : 396-8800 (7863)
>
>
>
>  "Network design is 50 percent technology, 50 percent diplomacy, 50  
> percent magic"
>
>
>
>