[rtgwg] draft-ietf-rtgwg-mrt-frr-algorithm-03

"Anil Kumar S N (VRP Network BL)" <anil.sn@huawei.com> Sun, 21 June 2015 13:07 UTC

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From: "Anil Kumar S N (VRP Network BL)" <anil.sn@huawei.com>
To: Chris Bowers <cbowers@juniper.net>, Gábor Sándor Enyedi <gabor.sandor.enyedi@ericsson.com>, "Andras.Csaszar@ericsson.com" <Andras.Csaszar@ericsson.com>, Alia Atlas <akatlas@juniper.net>, "abishek@ece.arizona.edu" <abishek@ece.arizona.edu>
Subject: [rtgwg] draft-ietf-rtgwg-mrt-frr-algorithm-03
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Date: Sun, 21 Jun 2015 13:06:50 +0000
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HI Authors,

Comment 1:
In below topology if [R] is the local root of the topology, Block id of R is 0 and Block ID of all other nodes in the topology as per psudo-code, I feel it should be 0/1 for all.
When Assign_Block_ID is invoked, root gets the blockid 0, then since first DFS child local root is GADAG root block id is incremented to 1 and assigned, for all other DFS child block-id
Is assigned without incrementing it gets the value 1.

             [E]----|
            (5,0)   |
              |     |
              |     |
             [R]   [D]---[C]
            (0,0) (4,0) (3,0)
              |           |
              |           |
             [A]---------[B]
            (1,0)       (2,0)



global_var: max_block_id

                 Assign_Block_ID(x, cur_block_id)
                   x.block_id = cur_block_id
                   foreach DFS child c of x
                      if (c.local_root is x)
                         max_block_id += 1
                         Assign_Block_ID(c, max_block_id)
                      else
                        Assign_Block_ID(c, cur_block_id)

                 max_block_id = 0
                 Assign_Block_ID(gadag_root, max_block_id)

Comment 2:  "This is necessary for the DFS in
   Lowpoint_Visit above, where the selection order of the interfaces to
   explore results in different trees."

This sentence can be changed,
"This is necessary for the DFS in  Lowpoint_Visit  as per section 4.3. , where the
selection order of the interfaces to explore results in different trees."

5.1.  Interface Ordering

   To ensure consistency in computation, all routers MUST order
   interfaces identically down to the set of links with the same metric
   to the same neighboring node.  This is necessary for the DFS in
   Lowpoint_Visit above, where the selection order of the interfaces to
   explore results in different trees.  Consistent interface ordering is
   also necessary for computing the GADAG, where the selection order of
   the interfaces to use to form ears can result in different GADAGs.
   It is also necessary for the topological sort described in
   Section 5.8, where different topological sort orderings can result in
   undirected links being added to the GADAG in different directions.

Thanks & Regards
Anil S N

"Be liberal in what you accept, and conservative in what you send" - Jon Postel