Subject: [pim] question about join-attributes

From: Cao Wei <[email-masked]>
Date: Fri, 17 Mar 2006 11:56:33 +0800

Hi, guys:
    I have read draft-ietf-pim-join-attributes-01 and have some puzzle to clarify:

1.  About conflicting attributes defined in section 3.4:
     My question is: how dose a router judge the attributes it receives are conflicting? 
     
For example, if node A has two downsteams named as B and C,
                      B                     
                 _ /
     -----A-----C
B sends join message without any attribute because B want to use the default exit point, while C sends join with attribute that require 
other exit point. Are these conflicting attributes? If they are conflicting, does this mean no-attribute join message will conflict with any other join message with specific attributes?

 2.  About attribute convergence defined in section 3.5
    As described in this section, "This PIM Pruen does not need to carry and Attribute", so consider the follow scenario:
                       C
                   _ /
     A-----B-----D
      
     B has two down streams C and D. First B receives a join message with  attribute a1, then B will propagate a1 to A. after a while,
     B receives attribute a2 from D. If a1 and a2 are NOT conflicting, should B send a message with both attribute a1 and a2 to A?
    I suppose so but not sure. If not, A will receive join message from B with only one attribute a2, then A will find that the join
     message from same downstream B had changed its attribute (from a1 to a2), then A may discard attribute a1 only take a2 as a valid
    attribute. This may cause  mis-understanding.

Thanks.                     Cao Wei

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