[rbridge] last call comment

[Radia Perlman]

Well, if we want to allow load splitting with at least p trees, then we 
have to keep p parents.

Alternatives to what is written, I think, are:

a) keep as is: while computing the tree, keep all p parents.

b) say that if p > j, then you only need to keep the top j choices of 
parent. (this
is true, and might be a good clarification to put in)

c) say that load splitting choices will never be more than, say, 5 (an 
architectural
constant we will choose now and be stuck with forever), and then say 
that the top
"5" choices of parents must be kept (so that the actual choice, for tree 
j, will
be j mod 5).

Choice b) does not affect the output-- it's just somewhat of an 
optimization for how
to compute the trees.

Would saying that be sufficient, or would you prefer that we actually 
limit the number of
potential load splitting choices?

Radia



Jeff Pickering wrote:
>    
>      Section 4.5.1
>  
>
>    "When building the tree number j, remember all possible equal cost
>
>    parents for node N. After calculating the entire "tree" (actually,
>
>    directed graph), for each node N, if N has "p" parents, then order
>
>    the parents according to 7-byte ID. For tree j, choose N's parent as
>
>    choice j mod p."
>
>  
>
>    I really dont like the idea of keeping all P parents, esp in an 
> environment
>
>    like fat tree where there may be dozens of upstream equal cost 
> parents (times thousands of nodes).
>
>       That said, we should at least say whether "order the parents" 
> means starting with lowest or highest.
>
>  
>
>  
>
>      Section 4.5.2
>
>  
>
>     
>
>       "In this case, R1-R2 adjacencies are ordered as follows, with
>
>       the one "most preferred" adjacency being the one that R1 transmits
>
>       to R2 on, and the one that R2 accepts traffic from R1 on:"
>
>  
>
>    
>
>       The way I read this, the statement is meaningless, R1 and R2 
> both transmit to each other. So
>
>       either the intent is to say R1 (or R2) is the RB closer to the 
> root. Or the intent is to say that depending
>
>       on whether traffic is flowing towards or away for the root, you 
> may choose a different adjacency. Whichever
>
>       interpretation is intended should be clarified.
>
>  
>
>     Section 4.5.2
>
>  
>
>  
>
>  
>
>  
>
>  
>
>       Jeff
>
>  
>
>  
>
>    
>
> ------------------------------------------------------------------------
>
> _______________________________________________
> rbridge mailing list
> rbridge at postel.org
> http://mailman.postel.org/mailman/listinfo/rbridge
>