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Thread: Questions on draft-nomadv6-mobileip-filters-03.txt.




Questions on draft-nomadv6-mobileip-filters-03.txt.
user name
2006-04-16 18:40:37
Hello everyone,

And now, some questions on
draft-nomadv6-mobileip-filters-03.txt.

1. Section 4.1.1 says:
  "Filters for Mobile IPv6 is applicable only in the
context of a mobile 
   node maintaining multiple points of attachment to one or
more 
   Internet administrative domains. ..."
  Why would not it be applicable with single point of
attachment. E.g. the
  MN may have multiple CoAs on its single interface but the
end-to-end
  characteristics of these CoAs may be different. Cannot it
be?
  E.g. packets to different CoAs may be routed on different
paths.

2. Section 4.1.1:
  "N    When set, the binding agent MUST act based on
the functions 
        described in section 4.1.3 and add a new entry to
the binding 
        cache without deleting any existing entries for the
mobile ..."
  I guess this does not mean that "if the N bit is set
then the agent
  MUST add a new entry". So I think this text should
be deleted or
  clarified.

3. What if the N-bit is set and the BU is a CoA
de-registration BU?
  E.g. Can a de-registration BU carry a Filter Deletion
Extension?

4. What is the mechanism of matching flows? First match the
destination
  address with a HoA and then find the proper CoA using the
filters?

5. Section 4.1.3:
  "then a new one will automatically be configured by
each involved 
   Filtering Agent to the lowest possible Index of 0. 
"
  What does "configured" mean? Created? So the
Agent would then create
  a Default filter for the HoA that has index 0, weight 1
and applies
  to any packet? Just because it is not clear from the text.

6. How does the MN specify the Default Filter? With a BU,
N-bit set,
  no Filter Modules but only an FCL with index 0? Or can the
Default Filter
  be more specific than "match any packet", that
is, specifying with a BU,
  N-bit set, Filter Modules and an FCL with index 0?

7. At an agent, does every registered HoA have a Default
Filter
  (or rather a Default Binding or Default CoA)?

8. Section 4.1.4:
  "binding. If the lifetime of a binding expires or it
is cancelled by 
   the registration of another mobility binding ..."
  Cancellation means "deletion" here? If yes, is
it so that it can happen
  only if the MN sends a BU with the N-bit not set while
having multiple
  bindings for the corresponding HoA?
  What about an RFC3775 de-registration BU? Is that
"cancellation"?
  And if "all associated Filters are deleted from the
binding cache" then
  what about shared Filters? Do you delete a shared Filter
even if its
  still valid for another Binding Cache entry (a Binding)?
  Oh, yes, and what is the lifetime of a shared Filter?

9. The first paragraph of Section 4.1.6 is overcomplicated.
Does not it say
  that a CoA can be bound to multiple HoAs of the MN?
  And in the second paragraph, cannot the MN send the BU for
HoA-A from B
  without AltCoA? I think it can.

10. In section 4.1.7 it says:
  "points of attachment, the mobile node MUST
de-register all the other 
   bindings that belong to the same home IP address.
..."
  Does the MN need to de-register even at the CNs? Is it for
keeping things
  clean and simple? I mean, is the idea that if we are at
the network of a
  HoA with an interface then forget this draft for that HoA?

11. Section 4.2:
  "When MN requires transferring flow `d to the
interface connected to 
   FN-B, MN sends a binding update with HoA-2 and CoA-C,
together with 
   CoA-B in the Alternate care-of-address mobility option
and with the 
   required filtering extensions (see section 4.1.6).
..."
  I guess it is just an example but just in case, I'd like
to note that
  the BU could be sent from B without AltCoA.
  And also, in the previous paragraph the N-bit was set, and
here no text
  about the N-bit. It is obviously set here too, but still.

12. Section 5:
  "... in the destination option. Binding updates
without the N 
   bit set are considered as idle mobility bindings.
..."
  Just for clarification, I guess Binding != BU. Rather a
Binding is an
  association represented by a Binding Cache Entry.
  Is a NOMADv6 BU without N-bit set the same as an RFC3775
BU?
  So I guess it's more like "Binding updates without
the N 
  bit set create idle mobility bindings.". No?

13. So what does this N-bit indicate? Does it indicate that
  a) enable multiple bindings for the HoA in this BU
___AND___
  b) this BU contains filter description(s)/actions?

14. Section 6.1:
  "...Filters will be associated with the registered
care-of address at all 
   Filtering Agents (HA,CN,MAP). A mobile node that
maintains multiple 
   points of attachment may request for simultaneous
mobility bindings 
   by setting the N bit in its binding Updates. ... "
  I guess the "...Filters will be associated with the
registered care-of
  address at the Filtering Agent (HA, CN or MAP)".
  Also, what about a MN with a single point of attachment
having multiple
  CoAs? It "may request for simultaneous mobility
bindings" too.

15. A Filter can be shared between different Bindings and a
Binding can be
  associated with multiple Filters.
  For me this tells that Bindings and Filters should be
allowed to be
  handled independently and stored in separate
"Databases". E.g. according
  to this draft if you want to change only the CoA of an
existing Binding
  at the Filtering Agent then you have to send two BUs. One
for creating a
  Binding with the new CoA and associated with the same
Filter and another
  BU to remove the other Binding.
  BID of draft-wakikawa-mobileip-multiplecoa-05.txt might
come handy ;)

16. In Section 6.1.2, does the replacing of a shared filter
affect all the
  involved Bindings at the Filtering Agent and not only the
one indicated
  by this BU?

17. In Section 6.1.5, how can a single BU re-new the
lifetime of all the
  Bindings of a HoA?
  The lifetime belongs not only to the HoA but to a Binding
and
  a Binding is identified by (HoA, CoA). Or not?

18. So Section 6.1.6 and 6.1.7 deletes only filters and does
not touch Bindings?
  First sign of handling filters independently from bindings


19. The 1st paragraph of Section 6.1.8 is quite
incomprehensible. Transferring a
  filter? FROM where TO where? Like dis-associating a filter
from Binding-A and 
  associating it with Binding-B?

20. The 2nd paragraph of Section 6.1.8 is lost and is
desperately looking for its
  place in the draft . And also:
  "... by the corresponding mobility binding. In the
case of 
   shared Filters, packets of matching flows will get
distributed 
   between multiple points of attachment with respect to the
Weight 
   value of each Filter."
  I thought a shared Filter was "shared" between
multiple Bindings. Does "shared
  Filter" mean a Binding with multiple Filters. Just
because I cannot see how
  the weight of a Filter can control distribution on
multiple PoAs.
  Should not the weight be associated with Bindings rather
than Filters in this
  case?
  Or is the semantic of "weight" implementation
specific?

21. Section 6.2:
  "Should the Filtering Agent succeed in applying the
Filters, then the 
   Filtering Acknowledgement indicating the index of the
success MUST be 
   sent, only if `A bit is set on the Binding Update.
"
  What about registration with the HA? No Filtering Ack?
There is BA...
  "When a mobility binding expires or is deregistered
by a mobile node  
   then all associated Filters are deleted with it.
..."
  What about shared filters?

22. Section 7:
  "once. A Filter Module may include one or more
predicates. ..."
  What are predicates? Give me an example of a Filter Module
with multiple
  predicates please because I don't get it from the text!

That's all for now 

Thanks,
Gabor


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