Re: What is an IGMPv3 Router's initial current state for amulticast group?

Hi Suvendu,
 
There is no initial state in the IGMP router for a multicast group before the router receives an IGMP membership report for that multicast group. The IGMPv3 router creates the register for each multicast group after receiving the membership report asking  for multicast traffic.
 
Also the first report received by the router should be of the type IS_IN or IS_EX
 
no initial state + report IS_IN(B) -> final state = INCLUDE(B)
no initial state + report IS_EX(B) -> final state = EXCLUDE ({}, B)

I think the general rule should be::

no initial state + membership report asking for some multicast traffic1 -> final state of the router is the router sending that traffic1 and only that traffic1

Alvaro


________________________________

De: Suvendu Mozumdar [mailto:[email protected]]
Enviado el: mié 05/03/2008 9:07
Para: Alvaro Fernandez; [email protected]
Asunto: RE: [magma] What is an IGMPv3 Router's initial current state for amulticast group?



Thanks for replying. You have answered my question based on the example I cited. But the question was more generic. What should the router consider as initial state when it has received the first report for a particular group. You have considered it to be INCLUDE(A), but there is no A when the router has not seen the group before, is it NULL then?

 

________________________________

From: Alvaro Fernandez [mailto:[email protected]] 
Sent: Wednesday, March 05, 2008 1:26 PM
To: Suvendu Mozumdar; [email protected]
Subject: RE: [magma] What is an IGMPv3 Router's initial current state for amulticast group?

 

Hi:

 

Initial state INCLUDE(A)

messaje TO_EX(B)

Final state EXCLUDE(A*B,B-A)

 

In the case B is "NULL" ( a empty list {} ) in the message, then the final state must be EXCLUDE({}, {}) and it doesn't matter which is the intial state. Both the requested list and the exclude list must be empty lists in the final state.

 

If the above is a litle difficult to understand is because, from my point of view, the requested list is a very bad solution to keep track of include sources when the filter mode is EXCLUDE. 

 

I think it would be a good idea to fix this in IGMPv4

 

Regards

 

Alvaro

 

________________________________

De: [email protected] en nombre de Suvendu Mozumdar
Enviado el: mié 05/03/2008 7:40
Para: [email protected]
Asunto: [magma] What is an IGMPv3 Router's initial current state for amulticast group?

Hi,
      I have a query regarding the IGMPv3/MLD Router behaviour. In IGMPv3/MLDv2, the action of a router on receiving a report message for a particular Group depends on the router's current state for the group at the time of receiving the report, as defined in section 6.4 of RFC 3376. Now what should be a router's initial current state for a group when it has received the first report for the group, lets say a router comes up afresh and receives the first report message for a group G1 with filter mode TO_EX(NULL). Now it has to consider some initial current state for the group and then based on that it has to take an action for the TO_EX(NULL) report. 

My question is what should be a router's initial current state for a group. I feel it should be INCLUDE(NULL), please advise.

-- 
Suvendu Mozumdar.
QA Architect.
Ixia Technologies Pvt. Ltd
9th Floor, Infinity Tower II
Sector V, Saltlake.
Kolkata 700091.
INDIA.
Mob : +919874081221

_______________________________________________
magma mailing list
[email protected]
https://www.ietf.org/mailman/listinfo/magma