Multicasting

The BBC launched a multicasting trial last year along with ITV
(http://support.bbc.co.uk/multicast/streams.html), and more recently some of
the commercial radio companies have joined it, but the list of participating
ISPs doesn't seem to have grown much:

http://support.bbc.co.uk/multicast/isps.html

and the big ISPs are conspicuous by their absence. So I was wondering what
people on here think is the prospect for multicasting over the next 2-3
years, and whether people think that any of the big ISPs are going to
convert their networks to support multicasting. Also, what is currently
stopping the bigger ISPs from converting their networks to support
multicasting?

I've also got a couple of questions about BT's 21CN: will it be an IPv6
network and therefore natively support multicasting? And if so, once an area
has been converted to 21CN would broadband connections in that area then
natively support multicasting, or would it still require the individual ISPs
to convert their equipment as well?


--
Steve - www.digitalradiotech.co.uk - Digital Radio News & Info

Find the cheapest Freeview & DAB prices:
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DAB sounds worse than FM <dab.is@dead> wrote:
> The BBC launched a multicasting trial last year along with ITV
> (http://support.bbc.co.uk/multicast/streams.html), and more recently some of
> the commercial radio companies have joined it, but the list of participating
> ISPs doesn't seem to have grown much:
>
> http://support.bbc.co.uk/multicast/isps.html
>
> and the big ISPs are conspicuous by their absence. So I was wondering what
> people on here think is the prospect for multicasting over the next 2-3
> years, and whether people think that any of the big ISPs are going to
> convert their networks to support multicasting. Also, what is currently
> stopping the bigger ISPs from converting their networks to support
> multicasting?

AIUI.
For a non LLU ISP, using BT Centrals from the customers to the NOC,
there is no native support of multicasting. For ISPs with their own
bandwidth providers to the NOC, this may change.

A gigabyte costs about a pound to provide in peak time (as a
proportion of a BT central. (622 mbits, over a million a year to rent)

The ISP can possibly have multicast transmission to their NOC
but that's as far as it goes.

The connections to the end users are over completely isolated virtual
circuits, that only contend for bandwidth.

There is no mechanism in BTs current network for multicast traffic to
'break in' at the end of the circuit near the customer, it all needs
sent individually, even if there are thousands of copys of the same
packet going to the same exchange.

How 21CN changes this I don't know.
In principle, it could change.

The only 'near term' - 2-3 years change in the market that I'm aware of
is BT saying they are going to drop the price of centrals a bit.

Ian Stirling wrote:
> DAB sounds worse than FM <dab.is@dead> wrote:
>> The BBC launched a multicasting trial last year along with ITV
>> (http://support.bbc.co.uk/multicast/streams.html), and more recently
>> some of the commercial radio companies have joined it, but the list
>> of participating ISPs doesn't seem to have grown much:
>>
>> http://support.bbc.co.uk/multicast/isps.html
>>
>> and the big ISPs are conspicuous by their absence. So I was
>> wondering what people on here think is the prospect for multicasting
>> over the next 2-3 years, and whether people think that any of the
>> big ISPs are going to convert their networks to support
>> multicasting. Also, what is currently stopping the bigger ISPs from
>> converting their networks to support multicasting?
>
> AIUI.
> For a non LLU ISP, using BT Centrals from the customers to the NOC,
> there is no native support of multicasting. For ISPs with their own
> bandwidth providers to the NOC, this may change.
>
> A gigabyte costs about a pound to provide in peak time (as a
> proportion of a BT central. (622 mbits, over a million a year to rent)
>
> The ISP can possibly have multicast transmission to their NOC
> but that's as far as it goes.
>
> The connections to the end users are over completely isolated virtual
> circuits, that only contend for bandwidth.
>
> There is no mechanism in BTs current network for multicast traffic to
> 'break in' at the end of the circuit near the customer, it all needs
> sent individually, even if there are thousands of copys of the same
> packet going to the same exchange.


Okay, thanks for the above explanation.


> How 21CN changes this I don't know.
> In principle, it could change.


I think I'm right in saying that 21CN will be an IPv6 network, and IPv6 does
natively support multicasting:

http://en.wikipedia.org/wiki/Ipv6#Multicast

"Multicast is part of the base protocol suite in IPv6. This is in opposition
to IPv4, where multicast is optional.

Most environments do not currently have their network infrastructures
configured to route multicast; that is - the link-scoped aspect of multicast
will work but the site-scope, organization-scope and global-scope multicast
will not be routed."

So I think the crucial question is: when 21CN has been rolled out to a
certain area, will ADSL users in that area then be able to use multicasting,
or would it still require the individual ISPs to change their networks as
well?


> The only 'near term' - 2-3 years change in the market that I'm aware
> of is BT saying they are going to drop the price of centrals a bit.


Okay.


--
Steve - www.digitalradiotech.co.uk - Digital Radio News & Info

Find the cheapest Freeview & DAB prices:
http://www.digitalradiotech.co.uk/fr..._receivers.php
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DAB sounds worse than FM <dab.is@dead> wrote:
> Ian Stirling wrote:
>> DAB sounds worse than FM <dab.is@dead> wrote:
>>> The BBC launched a multicasting trial last year along with ITV
>>> (http://support.bbc.co.uk/multicast/streams.html), and more recently
>>> some of the commercial radio companies have joined it, but the list
>>> of participating ISPs doesn't seem to have grown much:
>>>
>>> http://support.bbc.co.uk/multicast/isps.html
>>>
>>> and the big ISPs are conspicuous by their absence. So I was
>>> wondering what people on here think is the prospect for multicasting
>>> over the next 2-3 years, and whether people think that any of the
>>> big ISPs are going to convert their networks to support
>>> multicasting. Also, what is currently stopping the bigger ISPs from
>>> converting their networks to support multicasting?
>>
>> AIUI.
>> For a non LLU ISP, using BT Centrals from the customers to the NOC,
>> there is no native support of multicasting. For ISPs with their own
>> bandwidth providers to the NOC, this may change.
>>
>> A gigabyte costs about a pound to provide in peak time (as a
>> proportion of a BT central. (622 mbits, over a million a year to rent)
>>
>> The ISP can possibly have multicast transmission to their NOC
>> but that's as far as it goes.
>>
>> The connections to the end users are over completely isolated virtual
>> circuits, that only contend for bandwidth.
>>
>> There is no mechanism in BTs current network for multicast traffic to
>> 'break in' at the end of the circuit near the customer, it all needs
>> sent individually, even if there are thousands of copys of the same
>> packet going to the same exchange.
>
>
> Okay, thanks for the above explanation.
>
>
>> How 21CN changes this I don't know.
>> In principle, it could change.
>
>
> I think I'm right in saying that 21CN will be an IPv6 network, and IPv6 does
> natively support multicasting:

Maybe.
Yes, it will be an IPv6 network, I don't think however it's been
revealed exactly how this is implemented.

If it's implemented as some sort of PPPoIP, or other virtual circuit,
from the customers ADSL linecard, to the ISP, then nothing - apart from
perhaps the cost - changes.

If each ADSL linecard has its own IP, connected by a pure IP network, there
are several implications.

How does charging work?

Might a gigabyte to my neighbour (with the linecard next to me) be
significatly cheaper than a gigabyte to London?

This would make peer-peer realtime video and radio of some sorts very
possible, and much, much kinder to the network than currently.

On 2007-01-22, Ian Stirling <(E-Mail Removed)> wrote:
> A gigabyte costs about a pound to provide in peak time (as a
> proportion of a BT central. (622 mbits, over a million a year to rent)

That's pretty funny. If you fetch this

http://www.soe.ucsc.edu/projects/pof/WSJ.pdf

you'll notice on page 2 that the wholesale price for 155 Mbps from
London to New York is US$3,400 per month. Doing the math this
means that a London<->New York 622 Mbps circuit would rent for
a bit under $165,000 per year. I guess it commands a 10x premium
when you call it a "central".

> The connections to the end users are over completely isolated virtual
> circuits, that only contend for bandwidth.

Or perhaps that is the problem? R&D for ATM switches stopped in about
1995, so anyone who is still using them for something is paying a
huge premium for hardware compared to packet equipment. Who ever
decided that the way to support DSL was to build an ATM backhaul
network made a huge mistake (I'll bet they got promoted afterward,
too).

Dennis Ferguson

On Tue, 23 Jan 2007 11:21:37 -0600, Dennis Ferguson
<(E-Mail Removed)> wrote:

> I guess it commands a 10x premium
>when you call it a "central".

no, it commands a premium when it pays for connection to 5,500
telephone exchanges rather than a single point to point link over the
Atlantic where there is plenty of surplus capacity - much of it
acquired from companies that went bust.

Phil

On 2007-01-22, DAB sounds worse than FM <dab.is@dead> wrote:
> and the big ISPs are conspicuous by their absence. So I was wondering what
> people on here think is the prospect for multicasting over the next 2-3
> years, and whether people think that any of the big ISPs are going to
> convert their networks to support multicasting. Also, what is currently
> stopping the bigger ISPs from converting their networks to support
> multicasting?

I've done development work on multicast routing protocols and I can tell
you that multicast routing is a really tough, difficult to scale, problem.
I've seen this stuff usefully deployed in smaller networks, but in a
large network (let alone, say, an entire country) the routers are already
working hard and turning on multicast routing is like adding insult to
injury. That's not to say it won't be done; things can always be made to
work if you are willing to suffer long enough. I just wouldn't rank the
likelihood of multicast deployment on a large scale at a high probability.

> I've also got a couple of questions about BT's 21CN: will it be an IPv6
> network and therefore natively support multicasting? And if so, once an area
> has been converted to 21CN would broadband connections in that area then
> natively support multicasting, or would it still require the individual ISPs
> to convert their equipment as well?

Note that the problem of routing IPv6 multicast is identical to the problem
of routing IPv4 multicast; if you don't want to run one of them you are
unlikely to want to run the other. And I'm not sure about the need to
"convert equipment" to run multicast (with the exception of certain
backhaul edge networks of unfortunate design); routers have supported
the functionality for years, it is mostly just that no one wants to
turn it on.

Dennis Ferguson

On 2007-01-23, Phil Thompson <(E-Mail Removed)> wrote:
> On Tue, 23 Jan 2007 11:21:37 -0600, Dennis Ferguson
><(E-Mail Removed)> wrote:
>
>> I guess it commands a 10x premium
>>when you call it a "central".
>
> no, it commands a premium when it pays for connection to 5,500
> telephone exchanges rather than a single point to point link over the
> Atlantic where there is plenty of surplus capacity - much of it
> acquired from companies that went bust.

Despite that, bandwidth is still inherently more expensive on the
transatlantic route because of the limitations on the use of WDM there
which don't exist on land routes.

In any case, I think I otherwise might have made your point in the part of
the post you deleted, where I said:

>>> The connections to the end users are over completely isolated virtual
>>> circuits, that only contend for bandwidth.
>>
>> Or perhaps that is the problem? R&D for ATM switches stopped in about
>> 1995, so anyone who is still using them for something is paying a
>> huge premium for hardware compared to packet equipment. Who ever
>> decided that the way to support DSL was to build an ATM backhaul
>> network made a huge mistake (I'll bet they got promoted afterward,
>> too).

I don't think 5,500 is the problem, though how the 5,500 are connected
may be.

Dennis Ferguson

Ian Stirling wrote:
> DAB sounds worse than FM <dab.is@dead> wrote:
>> Ian Stirling wrote:
>>> DAB sounds worse than FM <dab.is@dead> wrote:
>>>> The BBC launched a multicasting trial last year along with ITV
>>>> (http://support.bbc.co.uk/multicast/streams.html), and more
>>>> recently some of the commercial radio companies have joined it,
>>>> but the list of participating ISPs doesn't seem to have grown much:
>>>>
>>>> http://support.bbc.co.uk/multicast/isps.html
>>>>
>>>> and the big ISPs are conspicuous by their absence. So I was
>>>> wondering what people on here think is the prospect for
>>>> multicasting over the next 2-3 years, and whether people think
>>>> that any of the big ISPs are going to convert their networks to
>>>> support multicasting. Also, what is currently stopping the bigger
>>>> ISPs from converting their networks to support multicasting?
>>>
>>> AIUI.
>>> For a non LLU ISP, using BT Centrals from the customers to the NOC,
>>> there is no native support of multicasting. For ISPs with their own
>>> bandwidth providers to the NOC, this may change.
>>>
>>> A gigabyte costs about a pound to provide in peak time (as a
>>> proportion of a BT central. (622 mbits, over a million a year to
>>> rent)
>>>
>>> The ISP can possibly have multicast transmission to their NOC
>>> but that's as far as it goes.
>>>
>>> The connections to the end users are over completely isolated
>>> virtual circuits, that only contend for bandwidth.
>>>
>>> There is no mechanism in BTs current network for multicast traffic
>>> to 'break in' at the end of the circuit near the customer, it all
>>> needs sent individually, even if there are thousands of copys of
>>> the same packet going to the same exchange.
>>
>>
>> Okay, thanks for the above explanation.
>>
>>
>>> How 21CN changes this I don't know.
>>> In principle, it could change.
>>
>>
>> I think I'm right in saying that 21CN will be an IPv6 network, and
>> IPv6 does natively support multicasting:
>
> Maybe.
> Yes, it will be an IPv6 network, I don't think however it's been
> revealed exactly how this is implemented.
>
> If it's implemented as some sort of PPPoIP, or other virtual circuit,
> from the customers ADSL linecard, to the ISP, then nothing - apart
> from perhaps the cost - changes.


Right.


> If each ADSL linecard has its own IP, connected by a pure IP network,
> there are several implications.
>
> How does charging work?
>
> Might a gigabyte to my neighbour (with the linecard next to me) be
> significatly cheaper than a gigabyte to London?
>
> This would make peer-peer realtime video and radio of some sorts very
> possible, and much, much kinder to the network than currently.


Okay, thanks again for the explanation.


--
Steve - www.digitalradiotech.co.uk - Digital Radio News & Info

Find the cheapest Freeview & DAB prices:
http://www.digitalradiotech.co.uk/fr..._receivers.php
http://www.digitalradiotech.co.uk/dab/dab_radios.php

Dennis Ferguson wrote:
> On 2007-01-22, DAB sounds worse than FM <dab.is@dead> wrote:
>> and the big ISPs are conspicuous by their absence. So I was
>> wondering what people on here think is the prospect for multicasting
>> over the next 2-3 years, and whether people think that any of the
>> big ISPs are going to convert their networks to support
>> multicasting. Also, what is currently stopping the bigger ISPs from
>> converting their networks to support multicasting?
>
> I've done development work on multicast routing protocols and I can
> tell you that multicast routing is a really tough, difficult to
> scale, problem.


If an ISP limited multicasting support to just the 30 or so channels on the
BBC's multicasting trial:

http://support.bbc.co.uk/multicast/streams.html

rather than supporting an unlimited number of multicast streams, would that
make the problem more tractable?


> I've seen this stuff usefully deployed in smaller
> networks, but in a
> large network (let alone, say, an entire country) the routers are
> already working hard and turning on multicast routing is like adding
> insult to injury. That's not to say it won't be done; things can
> always be made to work if you are willing to suffer long enough. I
> just wouldn't rank the likelihood of multicast deployment on a large
> scale at a high probability.


Do you think that as the demand for live streamed TV increases a time will
come when it becomes in the ISPs' own interest to support multicasting? The
alternative is having shitloads of unicast and P2P streams flying around,
which I'd have thought would provide a greater strain on bandwidth/routing
(although admittedly I don't actually understand the situation very well).


>> I've also got a couple of questions about BT's 21CN: will it be an
>> IPv6 network and therefore natively support multicasting? And if so,
>> once an area has been converted to 21CN would broadband connections
>> in that area then natively support multicasting, or would it still
>> require the individual ISPs to convert their equipment as well?
>
> Note that the problem of routing IPv6 multicast is identical to the
> problem of routing IPv4 multicast; if you don't want to run one of
> them you are unlikely to want to run the other.


Right.


> And I'm not sure
> about the need to "convert equipment" to run multicast (with the
> exception of certain backhaul edge networks of unfortunate design);
> routers have supported
> the functionality for years, it is mostly just that no one wants to
> turn it on.


Fair enough.


--
Steve - www.digitalradiotech.co.uk - Digital Radio News & Info

Find the cheapest Freeview & DAB prices:
http://www.digitalradiotech.co.uk/fr..._receivers.php
http://www.digitalradiotech.co.uk/dab/dab_radios.php