ISDN and multicast: how?

ISDN and multicast: how?

Post by Lupo Buon » Tue, 22 Jul 2003 18:47:54



Hi all,
I have no previous ISDN experience, so I hope someone here can
enlighten me a bit about a problem I am facing.

One of our customers is planning to upgrade an aging 2400 bps RS232
based network to ISDN. The system is composed by a central node which
broadcasts periodic messages (about one 50 bytes message per second)
to some 100 remote stations.

The central issue of this revamping would be to keep the broadcasting
capability. The traffic on that network is not heavy but they have
many stations and they plan to add more so we have some scalability
requirements too.

I was thinking may be IP multicast could be a good candidate, but

- It looks like ISDN in and of itself does not support multicast.

- Apparently, this can be worked around by adding a router capable
  of multicast tunneling.

If all the above is correct, and considering that apart from
the multicast traffic there will be some TCP traffic too,
are the following statements correct:

1) I need to add a router at the central node to enable
   the tunneling

2) There's no need to add anything at the remote nodes

3) I assume this tunneling issue is well known and most
   routers support it

4) suggestions for a good router (possibly not costing
   an arm and an eye)?

5) Is there anything that I am overlooking?

Sorry if some questions may sound silly but as I said, I know
zip about ISDN.

Thanks for any help/suggestions,
Marco

+--
I know you can't speak, I know you can't sign
So cry right here on the dotted line

 
 
 

ISDN and multicast: how?

Post by Jochen Klei » Tue, 22 Jul 2003 21:22:15


Hi,

Quote:> I have no previous ISDN experience, so I hope someone here can
> enlighten me a bit about a problem I am facing.
> One of our customers is planning to upgrade an aging 2400 bps RS232
> based network to ISDN.

What do you mean with 2400 Bps RS232 network? Has he realy built a ntwork
between several computers with  (at least) 3 wire, running 2400 Bps?!??
Heard of such a installtion, last time, about 15 years ago :-)

Quote:> The system is composed by a central node which
> broadcasts periodic messages (about one 50 bytes message per second)
> to some 100 remote stations.

A RS232 based network with some 100 stations?!?? Are you sure????

Quote:> The central issue of this revamping would be to keep the broadcasting
> capability. The traffic on that network is not heavy but they have
> many stations and they plan to add more so we have some scalability
> requirements too.

 > I was thinking may be IP multicast could be a good candidate, but
Yep, that could be a solution.

Quote:> - It looks like ISDN in and of itself does not support multicast.

?!????? Errr, well, Juts one line above you worte about IP
(InternetProtocoll) broadcast, and now about ISDN (which reads Integrated
services digital network, not Internet services digital network :-) )
Ofcourse there is nothing like multicast in ISDN, cause its a line (not a
packet) switched network. (At least as far were not talking about X.31 =
X.25 over ISDN D-channel)

Quote:> - Apparently, this can be worked around by adding a router capable
>   of multicast tunneling.

Dont mix up ISDN (line switched) and IP (packet switched) networks!

 > If all the above is correct, and considering that apart from

Quote:> the multicast traffic there will be some TCP traffic too,
> are the following statements correct:

Well basicly all this IP (TCP, UDP, ...) issues have nothing to do with
ISDN!
I guess why youre talking about ISDN at all is, you want to use it as a
dialup connection to a Internet provider; is this correct?

Quote:> 1) I need to add a router at the central node to enable
>    the tunneling
> 2) There's no need to add anything at the remote nodes

Remote nodes??? In a RS232 based network?!?
If they are realy remote, so how are the connected to the central node? By
which ind of cbale, network,...?
If you wnat to swicth form what ever might be running at the moment, (I cant
realy imagein waht could this be) to IP ofcourse yu must add some kind of
Internet connection device to the remote nodes.

Quote:> 3) I assume this tunneling issue is well known and most
>    routers support it
> 4) suggestions for a good router (possibly not costing
>    an arm and an eye)?
> 5) Is there anything that I am overlooking?

I dont know.

Migth be you could explain a bit more in detail, what is (realy!) installed
now and whats the desired result you wnat to achiev with the solution youre
planing.

Regards,
Jochen Klein

 
 
 

1. Multicast Q - reducing multicast flood at the source's side

Dear ng,

1. what is best ? CGMP or IGMP snooping ?
2. I understand CGMP & IGMP snooping both rely on the exchange of IGMP
messages between the multicast receivers & the IGMP querier (most of the
time their default-gateway I guess). Therefore CGMP & IGMP snooping both
help in reducing multicast traffic at the receivers side.
Now what about reducing multicast traffic at the source's side ??
Since the source does not send IGMP messages, those techniques cant be
used right ?
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specific VLAN ?

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