Subject: Re: [PWE3] PWE3 Charter Update - **DRAFT Charter v0.1**

From: "Yaakov Stein" <[email-masked]>
Date: Tue, 13 May 2008 17:20:12 +0300

> Pt-mp PWs (and possibly tunnels) are required to support distribution
services. 
> As stated, pt-mp connections exist for many years in transport
networks, typically used in TV distribution services. 
> It is not the mainstream service type, but it is an important service
type.

> What you should not do is to emulate a n-port mp2mp service with a set
of p2p and p2mp PWs. 

Maarten

TV distribution of this type is being defined over IP as IPTV.
IPTV can traverse an MPLS network as IP packets.

What advantage do you see to defining a new PW service here?

I doubt the packet overhead is your problem as the overhead percentage
is low
since the packets tend to be rather large.

So are you aiming at QoS ?

Since IPTV is mostly a unidirectional service (unlike video
conferencing)
we can allow more delay than for interactive services.
Thus a combination of forward error correction, video packet loss
concealment,
and possible packet retransmission seems to make QoS less of a concern.

Perhaps your concern is manageability/billing and all the logistics
involved in them.
Unfortunately, PW technology does not have anything substantive to offer
here.

Can you explain why you believe that extending PWs to p2mp solves any
IPTV problem ?

Y(J)S
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---

From: "BOCCI Matthew" <[email-masked]>
Date: Tue, 13 May 2008 16:49:27 +0200

Yaakov,
 
> IPTV can traverse an MPLS network as IP packets.

Not all of it. There are DVB-T distribution networks that use native ATM
multicast today. 

Matthew 

> I doubt the packet overhead is your problem as the overhead 
> percentage is low since the packets tend to be rather large.
> 
> Thus a combination of forward error correction, video packet 
> loss concealment, and possible packet retransmission seems to 
> make QoS less of a concern.
> 
> Perhaps your concern is manageability/billing and all the 
> logistics involved in them.
> Unfortunately, PW technology does not have anything 
> substantive to offer here.
> 
> Can you explain why you believe that extending PWs to p2mp 
> solves any IPTV problem ?
> 
> Y(J)S

---

From: Maarten Vissers <[email-masked]>
Date: Wed, 14 May 2008 09:13:24 +0200

Yaakov,

In the early '90s TV channels were already distributed over SDH networks
(e.g. rings) using unidirectional p2mp VC-3 connections. At those days TV
channels were encoded in 34 Mbit/s. A number of TV channels entered the e.g.
SDH ring at node A and was then distributed around the ring and dropped in
every other node on the ring (B,C,D,E,..). To protect this TV distribution,
a second copy of the TV channels was send in the other direction around the
ring as well using the return timeslot (i.e. only one bidirectional timeslot
was used around the ring to provide a protected TV distribution service).

In today's networks, a Broadcast TV server node is to be connected with e.g.
thousand DSLAMs to deliver e.g. 70 TV channels. In Standard Definition
format this requires about 300 Mbit/s of (CIR) bandwidth. As all TV channels
have to be delivered to each DSLAM (assuming that all DSLAMs can be reached
through the packet transport network and that all DSLAMs have enough input
capacity (e.g. dedicated 1GE port for this service type)), then the packet
transport network can carry the set of 70 TV channels as one Ethernet p2mp
service. It is totally unimportant for the transport netowrk that there is
IP in the stack of the service signals. For the transport network those TV
channels present themselves as Ethernet signals, and are carried as an
Ethernet service.

This set of 70 TV channels can be carried over a single p2mp PW
(EthernetoverPW) to the T-PEs connected to the 1000 DSLAMs.

As a first alternative, those TV channels could be carried over a signle
p2mp MPLS Tunnel to the T-PEs connected to the 1000 DSLAMs.

As a second alternative, those 70 TV channels can be carried over a single
rooted-mp VPLS to the T-PEs connected to the 1000 DSLAMs. With IGMP you can
now limit the number of TV channels on a spoke to the subset of channels
actually being looked at by a subscriber. Such would be required when the
DSLAM has not enough capacity on its input port to support all 70 channels,
or when the transport network has not enough capacity on the links towards
some of the DSLAMs.

When in the future those TV channels need to be carried in High Definition
(HD) format as well, you need about 1 Gbit/s. At this point it will be
better to use a p2mp ODU0 in the next gen OTN to carry the 1 GE signal
(including those TV channels) from the Broadcast TV server to a 1GE port on
each of the 1000 DSLAMs.

As you can see, there is no need to carry TV channels as IP packets over a
transport network.

Regards,
Maarten

-----Original Message-----
From: Yaakov Stein [mailto:[email-masked]] 
Sent: 13 May 2008 16:20
To: Maarten Vissers
Cc: [email-masked]
Subject: RE: [PWE3] PWE3 Charter Update - **DRAFT Charter v0.1**

services. 
type.

of p2p and p2mp PWs. 

Maarten

I doubt the packet overhead is your problem as the overhead percentage is
low since the packets tend to be rather large.

Since IPTV is mostly a unidirectional service (unlike video
conferencing)
we can allow more delay than for interactive services.
Thus a combination of forward error correction, video packet loss
concealment, and possible packet retransmission seems to make QoS less of a
concern.

Perhaps your concern is manageability/billing and all the logistics involved
in them.
Unfortunately, PW technology does not have anything substantive to offer
here.

Can you explain why you believe that extending PWs to p2mp solves any IPTV
problem ?

Y(J)S