Whether an interface supports multicast or not depends on how
manufactures implement it (Hardware support), I think it's independent
of the protocol specification.

ie: If an interface supports multicast it can send multicast packets,
but if an interface doesn't support, software may do the job, so I
think they're the same.

Am I right?
If not, what's the difference between "support" and "not support"
exactly?

"lostlander" <lostlander.tom@gmail.com> wrote:

> Whether an interface supports multicast or not depends on how
> manufactures implement it (Hardware support), I think it's independent
> of the protocol specification.
>
> ie: If an interface supports multicast it can send multicast packets,
> but if an interface doesn't support, software may do the job, so I
> think they're the same.
>
> Am I right?
> If not, what's the difference between "support" and "not support"
> exactly?

The best definition of what it means is probably given in RFC 1112,
Section 3. There are different levels of "support." Simply sending
multicast datagrams is one, and joining multicast groups, in addition to
being able to send multicast datagrams, is another.

RFC 2189 talks about a specific routing protocol. It applies to routers
rather than clients.

Bert

On Apr 16, 10:10 pm, "Albert Manfredi" <albert.e.manfr...@nospam.com>
wrote:
> "lostlander" <lostlander....@gmail.com> wrote:
> > Whether an interface supports multicast or not depends on how
> > manufactures implement it (Hardware support), I think it's independent
> > of the protocol specification.
>
> > ie: If an interface supports multicast it can send multicast packets,
> > but if an interface doesn't support, software may do the job, so I
> > think they're the same.
>
> > Am I right?
> > If not, what's the difference between "support" and "not support"
> > exactly?
>
> The best definition of what it means is probably given in RFC 1112,
> Section 3. There are different levels of "support." Simply sending
> multicast datagrams is one, and joining multicast groups, in addition to
> being able to send multicast datagrams, is another.
>
> RFC 2189 talks about a specific routing protocol. It applies to routers
> rather than clients.
>
> Bert

Hi, Bert, thanks for your reply.

If the interface doesn't support multicast, it would be unicast, so
how the unicast pakcet is formed from previous multicast pakcet?

Regards
Tom

"lostlander" <lostlander.tom@gmail.com> wrote:

>> The best definition of what it means is probably given in RFC 1112,
>> Section 3. There are different levels of "support." Simply sending
>> multicast datagrams is one, and joining multicast groups, in addition
>> to
>> being able to send multicast datagrams, is another.
>>
>> RFC 2189 talks about a specific routing protocol. It applies to
>> routers
>> rather than clients.
>>
>> Bert
>
> Hi, Bert, thanks for your reply.
>
> If the interface doesn't support multicast, it would be unicast, so
> how the unicast pakcet is formed from previous multicast pakcet?

Not sure what you're asking. A unicast packet is not typically formed
from a multicast packet. Under normal circumstances, an interface not
set up for multicast cannot send packets with Class D addressing, nor
can it join multicast groups. Often, even if a client does support
multicast, the edge router to this client's subnet might not. So again,
no multicast support.

That's why streaming media servers usually provide multiple unicast
options as well as multicast. Is this what you were asking?

Bert

On Apr 17, 10:09 pm, "Albert Manfredi" <albert.e.manfr...@nospam.com>
wrote:
> "lostlander" <lostlander....@gmail.com> wrote:
> >> The best definition of what it means is probably given in RFC 1112,
> >> Section 3. There are different levels of "support." Simply sending
> >> multicast datagrams is one, and joining multicast groups, in addition
> >> to
> >> being able to send multicast datagrams, is another.
>
> >> RFC 2189 talks about a specific routing protocol. It applies to
> >> routers
> >> rather than clients.
>
> >> Bert
>
> > Hi, Bert, thanks for your reply.
>
> > If the interface doesn't support multicast, it would be unicast, so
> > how the unicast pakcet is formed from previous multicast pakcet?
>
> Not sure what you're asking. A unicast packet is not typically formed
> from a multicast packet. Under normal circumstances, an interface not
> set up for multicast cannot send packets with Class D addressing, nor
> can it join multicast groups. Often, even if a client does support
> multicast, the edge router to this client's subnet might not. So again,
> no multicast support.
>
> That's why streaming media servers usually provide multiple unicast
> options as well as multicast. Is this what you were asking?
>
> Bert- Hide quoted text -
>
> - Show quoted text -

I mean in CBT, if a multicast pakcet comes in, but the outgoing
interface doesn't support multicast, so it would be unicast.

I'm not sure how this process is done, and the rfc2189 doesn't say
more about it, so i thought it maybe a general trick.....

After I read more about it, i think i've understood the progress
now.

Thanks really!

Tom