Re: can ssm and non-ssm colide ?

[Jaiwant Mulik <jmulik@unix.temple.edu>]

Hi,

What again is ISM (I know SSM) ?

bye,

On Thu, 23 Nov 2000, Marshall Eubanks wrote:

> Dany Shterman wrote:
> > 
> >     Hi.
> > I understand that a router can have 2 types of multicast forwarding rules:
> > 
> > 1. (S,D) : i.e do multicast to a packet that arrives with IP destination
> > "d" and IP source "s" iff S=="s" and D=="d". 2. (*,D) : i.e do multicast to
> > a packet that arrives with IP destination   "d" iff D=="d".
> > 
> > Questions:
> > a. is it true ?
> > b. is it possible that a router will have 2 contradicting forwarding   rules
> > : (S,D) and (*,D) that direct traffic to 2 different ports,   for the same
> > IP destination address D ?
> > c. If the answer to the previous question is true, then to what port
> > should the router forward ?
> > 
> > ThankX.
> > Dan
> > 
> > _____________________________________________________________________________________
> 
> What exactly do you mean ? Is D the multicast class D address ? This
> is generally called "G", for the group. It is NOT a destination.
> 
> Remember, SSM and ISM address ranges are supposed to be disjoint - 
> (S,G) is allowed in a SSM range, but (*,G) is supposed to be
> filtered out. So this cannot occur in a proper SSM implementation. If  you
> tried to do ISM in the SSM address space, it wouldn't work.
> 
> In PIM-SM ISM, 
> a (*,G) JOIN and an (S,G) join certainly could have different directions -
> generally, they would. You could, for instance, be sending
> encapsulated multicasts to the RP, and then having them multicasted
> back to a receiver on the same LAN as you, so that the same data flow
> along the pipe in both directions.
> 
> >From 
> 
> 
>                                    Regards
>                                    Marshall Eubanks
> 
> 
>    Multicast Technologies, Inc.
>    10301 Democracy Lane, Suite 201
>    Fairfax, Virginia 22030
>    Phone : 703-293-9624          Fax     : 703-293-9609     
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> 

Jaiwant Mulik                            
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