Subject: [pim] New updated and edited version of draft-sami-pim-ng

From: saeed sami <[email-masked]>
Date: Fri, 11 Apr 2014 03:25:59 +0430

A new version of draft-sami-pim-ng is submitted and can be reached at :
http://www.ietf.org/internet-drafts/draft-sami-pim-ng-02.txt

It is edited and some parts and sections are updated.

Your reviews and comments are most appreciated. and I hope to read the
comments of PIM working group experts soon.

Abstract:
   This document specifies protocol independent multicast- Next
   generation or simply called PIM-NG. like PIM-SM, PIM-NG uses the
   underlying unicast routing information, but unlike PIM-SM it doesn't
   necessarily need to build unidirectional shared trees rooted at a
   Rendezvous Point (RP) per group, due to the fact that the processes
   through which a source registers with the Rendezvous Point and a host
   finds the source of the multicast destination groups it needs are
   done in a whole new way. So at some points PIM-NG works faster than
   its predecessor. Also the new Domain concept, unique to PIM-NG, along
   the RPF check method used in PIM-NG specifications provides many
   features along a robust and flexible control and administration over
   multicast networks.

-- 
sincerely yours
MR.SAEED SAMI

---

From: Stig Venaas <[email-masked]>
Date: Thu, 24 Apr 2014 14:24:56 -0700

Hi

I have some comments on your draft. I've been hoping that others in the
working group would also comment on this. Maybe with my comments here we
can start a discussion and hopefully also get others in the working
group to take part.

>     features along a robust and flexible control and administration over

I see you have put a lot of work into this. There are a lot of concepts
defined, new message types etc. but I think the main difference from
PIM-SM that I want to focus on is the source discovery part (including
the behavior of RPs). I have not read about the domain concept in detail
yet. I think parts of what you are proposing could be achieved without
necessarily having a completely new PIM protocol.

Both in PIM-SM and in your proposal the RPs have knowledge of active
sources. How the RPs learn about the sources are not very different.

You propose a register message to be sent when the source becomes
active. It does not contain a data packet. With PIM-SM you could also
do this by sending a Null register. You also have periodic messages
for keeping this state alive, which is not really different from
sending periodic Null registers.

Your approach and the Null register approach work well except for one
issue. Initial data packets from a source would be dropped. This is a
concern for some applications. For many applications I think it is
acceptable though.

Now, what is very different in PIM-SM and your proposal is how the
last hop routers learn about active sources.

With your proposal my understanding is that a last hop router sends a
unicast query for sources to the RP to ask for active sources. Then you
have the last hop router send periodic queries every 30 seconds in case
there are new sources?

One issue I see here is scaling when there are a large number of last
hop routers. The more significant issue is I think that it may take up
to 30 seconds from a source starts sending until a last hop router
learns that the source is active. Is that correct? That is in my opinion
unacceptable for many applications. This could be improved if the RP
stores state, remembering that certain routers should be notified if a
new source becomes active. This could be a problem if there are a large
number of last hop routers though.

I can understand that it is nice to avoid data registers and shared
trees, but it has some impact on applications.

I would like to hear your thoughts on this. Both regarding my concerns
above, but also the advantages and issue you see with your approach
compared to PIM-SM.

I will be offline for the next 10 days, but hopefully this can get a
discussion started in the working group.

Stig

---

From: saeed sami <[email-masked]>
Date: Fri, 25 Apr 2014 04:12:52 +0330

Dear Mr.Venaas,
Hello
First of all let me thank you for your review, comments and the time you 
have
dedicated to review my work.
the answer to your questions are as follows which i hope will be satisfying:

1- Source register process in PIM-NG :
At the first glance the overall register process may seem similar to 
PIM-SM, but
the register process in PIM-NG is different from PIM-SM . bellow the 
process is
briefly explained to make it more clear:
- Source sends a unicast-encapsulated register message to the address of the
RP which only contains the unicast address of the source and multicast 
group
(G) it represents. this register message does not contain data packet.
- RP receives the register message and saves the information within the 
register
message inside a table called Multicast Mapping Table(MMT). the RP puts 
an entry
in MMT containing the unicast address of the source and the multicast 
group (G)
it represents alongside other information related to the source for 
further use.
- after puting an entry in MMT RP will send back an acknowledge to the 
source
which indicates the successful registration of the information sent by 
source.
- after receiving the acknowledge from the RP source will start sending 
keep-alive
messages to the RP as long as it represents the multicast traffic 
destined for (G).
- due to the above PIM-NG does not need initial data packet.

2- How a last hop (a router which shows interest to receive multicast 
traffic
destined fro (G) or needs to find the source for (G) )learns about 
active sources? :

- in PIM-NG and in the ID ,such a last hop router is called a client.
- In PIM-NG because of the way RP interacts with active sources and 
saves the
information regarding active sources within the Domain in MMT , last hop 
(client)
doesnt need to know about all the active sources within the Domain.
- considering the above, a client will contact the RP in case it needs 
to find the
source of multicast traffic destined for (G) by sending a 
unicast-encapsulated
request for source message to the RP indicating that it needs to find 
(S) for (G).
(( there wont be a join to RPT for (*,G)).
- after RP receives the request it will search the MMT or 
AMMT(Abriviated-MMT)
to see if it finds an entry for (S) which represents (G).
- if an entry is found in MMT or AMMT the RP will send a 
unicast-encapsulated
acknowledge back to the client using the client's unicast address. this 
acknowledge
contains the unicast address of the source for (G).
- if an entry is not found , a null acknowledge (*,G) will be sent back 
to the client.
- after receiving the acknowledge containing the unicast address of the 
source for
(G) the client will directly join the SPT for (S,G).
(( there will be no need for switching from RPT to SPT by the client 
(last hop) ))
- at this point a large number of clients or last hops wont be a problem 
due to the
fact that there wont be any join to RPT rooted at the RP and the RP acts 
as an
information station in PIM-NG which keeps the information regarding 
existing
sources.

3- will there be a 30 second delay between the time a source becomes 
active and
a last hop learns about it ? :

- since as soon as a source becomes active and the register message is 
sent to RP
the information related to it is saved in MMT or AMMT by the RP, as soon 
as a
client (last hop) comes up with the need to find the source , it will 
only need to
ask the RP. there will be no delay in finding the source.
- since after receiving the address of the source there wont be any join 
to RPT
rooted at the RP and the client(last hop) will immediately join the SPT 
for (G) using
the unicast address of the source received from the RP, there wont be 
any delays
and PIM-NG will be one cycle a head of PIM-SM since there is no 
switching from
RPT to SPT .
- the above being explained there wont be any delay.
- also because in PIM-NG neighbor routers inform each other about the 
groups
they are join the SPT for , if a neighboring PIM-NG router comes up 
later with the
need to find (S) for the same (G) a neighbor is joined the SPT for , 
there wont be
the need to send a request to RP and instead the client will send its 
join to its
neighbor.

I hope that the above explanations are satisfactory and i have been able 
to answer
your questions and shed some light over the proposed questions and doubts.

the above being explained, one of the advantages of PIM-NG is its source 
discovery
process which at some point works faster than PIM-SM.

since this email is getting long i will try to explain other advantages 
of PIM-NG in a
separate email.

thanks again and i hope to read the comments and thoughts of other WG 
members
soon.

---

From: saeed sami <[email-masked]>
Date: Wed, 30 Apr 2014 01:46:46 +0330

Dear Mr.Venaas,
Hello
First of all let me thank you for your review, comments and the time you 
have
dedicated to review my work "draft-sami-pim-ng-02".

http://tools.ietf.org/html/draft-sami-pim-ng-02

Since answering to your questions will be a little lengthy and can't be 
posted to PIM mailing list as a single email, I have to answer in 
separate parts. and this is part 1 of the series.

Please kindly find the answers and explanations to your questions and 
doubts bellow. i hope that as you mentioned in your email there will be 
more comments from other members after this.

The source discovery method used in PIM-NG in conjunction with other 
processes with regards to PIM-NG ANYCAST RP concept (many RPs inside the 
same domain for redundancy and high availability), inter-domain 
connectivity concepts and how the last hop (client) routers in different 
multicast domains will be able to find an active source, which provides 
a hierarchical design approach, seems to be necessary and more 
optimized. The new source discovery method used eliminates the need for 
first joining the RPT rooted at the RP and then switch from RPT to SPT 
by the last hop router (client) and works faster and more optimized and 
reduces the network resource consumption related to both bandwidth 
consumption due to RPT trees rooted at RP for each (*,G) or (S,G) , the 
need for the RP to save the state of RPT trees and also the need for the 
last hop switch over from RPT to SPT.

And putting together all different processes and definitions 
specifically designed and defined for PIM-NG specifications will clarify 
the need for a new PIM protocol. These processes and specifications are 
what making PIM-NG a much more optimized, easily expandable and more 
secure PIM protocol. Also considering its compatibility with PIM-SM, 
PIM-NG might be a potential candidate for WG adoption which i hope it 
happens.

I am going to explain about the domain concept in another email 
explaining some of the advantages of PIM-NG.

End of part 1.

---

From: saeed sami <[email-masked]>
Date: Wed, 30 Apr 2014 01:50:42 +0330

Dear Mr.Venaas,
Hello

End of part 1.