Re: Comments on draft-dimitri-ccamp-gmpls-ason-routing-ospf-00.txt

[[e-mail]]

hi acee - thanks for commenting 

one or two hints below such as to clarify some point you mentioned here 
below




Acee Lindem <[e-mail]>
Sent by: [e-mail]
06/07/2006 03:12
 
        To:     [e-mail]
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        Subject:        Comments on 
draft-dimitri-ccamp-gmpls-ason-routing-ospf-00.txt


Dimitri,

Here are my comments on the subject document:

General - Describe the relationship of OSPF areas to ASON RAs.
   Section 6.1 references     OSPF area ID but the relationship
   is implied.

[dp] point taken (i guess we did not do a sufficiently good
job in RFC 4258 and in the eval doc. as still some questioning
remains about information map)

Section  3.2 - The length calculation is simply wrong.  You
  really don't know how many prefixes you've got until you've
  parsed them.

[dp] which length are you referring to ? the prefix or the sub-TLV ?

Section 5.1 - RFC 3620 specifies that the Link-ID Sub-TLV
  specifies the router-id. Why do you need the remote router-id
  in this sub-TLV? Could the 5.2 sub-TLV satisfy the
  requirement?

[dp] it is not the router_id but the TE router_ID

[dp] the issue is that there is no more a there is no 
more a 1:1 relationship between the Router_ID and the TE 
Router_ID in the present context

Section 6.0 - You should NOT need to change OSPF flooding rules.
  In other words, I don't see the need to specify the following:

  The Opaque TE LSA re-origination is governed as follows:
    - If the target interface is associated to the same area as the
      one associated with the receiving interface, the Opaque LSA MUST
      NOT be re-originated out that interface.
    - If a match is found between the Advertising Router ID in the
      header of the received Opaque TE LSA and one of the Router ID
      belonging to the area of the target interface, the Opaque LSA
      MUST NOT be re-originated out that interface.
    - If these two conditions are not met the Opaque TE LSA MAY be re-
      originated.

  Rather you should specify rules for importing/exporting
  information between OSPF instances at different levels.

[dp] your proposal is thus to revise these as import/export rules ?
in order to prevent having specific flooding rules between levels
the point was to not expand too much on the communication process
(inside the entity) between level adjacent RCs but if this makes
you more confortable i can revise as import/export rules

Section 6.1 While an RA is completely contained within a single
   parent layer RA. A given    RA may have multiple child RAs. 
Hence, the election algorithm is broken. 

[dp] to make it clear this is not an "election" process

At a minimum,
   you must advertise all your child areas.  Also, you MUST state
   that reachability is a precondition for considering a router
   eligible to pass information between levels.

[dp] upper not lower (it is a discovery from a given to an upper
parent viewpoint, where a child has a unique parent)

   Finally, since this is going to require advertisement of more
   than a single area-ID, please allocate a separate opaque LSA
   for ASON purposes.

[dp] having clarified the above is that still needed ?

Section 6.2 - Are you suggesting a single area ID or an area ID
   path (similar to the BGP AS path)? 

[dp] the former

I guess this may work if you
   always advertise you own area ID when redistributing between
   areas (relying on the fact that a child area is completely
   contained by its parent). I'm going to think more about this
   encourage others to do the same.

General: Have you considered aggregation?

[dp] at which level - reachability can be aggregated for inst.


Thanks,
Acee