Subject: [Monami6] Flow Bindings and destination address in draft-soliman-monami6-flow-binding-00.txt

From: Gábor Fekete <[email-masked]>
Date: Tue, 9 May 2006 15:09:09 +0300

Hi,

Is the Flow Binding(s) created always between the Binding indicated by
the BU and the Flow Identification option(s) carried in the same BU?

Is it correct if I say "A Flow Binding is an association between
a MIPv6 Binding (e.g. BC entry or BUL entry) and a Flow Identifier"?

Let's have an existing (HoA-1, CoA-1) default binding for MN at the HA.
Now, MN sends a BU with a Flow Identification option in a BU to HA
like the following:
o the CoA in the BU is CoA-1
o the HoA in the BU is HoA-1
o the dst addr in the Flow ID option is IP-X and the E flag set.
IP-X != HoA-1 and IP-X != CoA-1.
What kind of MIPv6 Binding and Flow Binding will it result?

Regards,
Gabor

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From: Andy Huang <[email-masked]>
Date: Tue, 23 May 2006 10:49:05 +0800

In my opinion,  it's reasonable that there is an association between a MIPv6 
Binding and some Flow Identifiers.

In your example:
if the existing (HoA-1, CoA-1) binding is the only binding or the default 
binding, I think it result nothing.

If not, it will result an association between the existing (HoA-1, CoA-1) 
binding and
the Flow Identifier(the dst addr in the Flow ID option is IP-X and the E 
flag set).

----- Original Message ----- 
From: "Gábor Fekete" <[email-masked]>
To: "Monami6 WG" <[email-masked]>
Sent: Tuesday, May 09, 2006 8:09 PM
Subject: [Monami6] Flow Bindings and destination address 
indraft-soliman-monami6-flow-binding-00.txt

---

From: Gábor Fekete <[email-masked]>
Date: Thu, 25 May 2006 12:33:33 +0300

Helo Andy,

Thank you for your response!

> Binding and some Flow Identifiers.
Great!

> binding, I think it result nothing.
What do you mean by "the only"? Do you mean the HA has only one binding for
HoA-1 in its BC and it is (HoA-1, CoA-1)?
Does "nothing" mean "the BU is silently ignored"?
Could you elaborate on this?

> the Flow Identifier(the dst addr in the Flow ID option is IP-X and the E 
OK. And then how would this association control a packet going through the HA
from CN destined to IP address IP-X? Will this Flow Identifier match this
packet?
I don't think it should if the Flow Identifier is bound to a Binding,
since IP-X != HoA-1.
What I don't understand is: Is the Flow Identifier supposed to work as a
selector (tie-breaker) of a specific CoA in case of multiple CoAs bound to
the same HoA (e.g. HoA-1)?

Regards,
Gabor Fekete

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From: Andy Huang <[email-masked]>
Date: Fri, 26 May 2006 12:20:54 +0800

Hello Gabor Fekete,

I didn't read the draft very carefully, here is my own thoughts, perhaps 
it's different from the draft.

----- Original Message ----- 
From: "Gábor Fekete" <[email-masked]>
To: "Monami6 WG" <[email-masked]>
Sent: Thursday, May 25, 2006 5:33 PM
Subject: Re: [Monami6] Flow Bindings and destination address 

> HoA-1 in its BC and it is (HoA-1, CoA-1)?

Yes, I did mean this.

> Could you elaborate on this?

If the existing (HoA-1, CoA-1) binding is the default binding,  all 
packets(all kinds of  FID) to HoA-1 must be sent to CoA-1, so HA need not 
create an association between the binding and the said FID. But HA must 
update the BC entry according to BU, the update process is described in 
RFC3775.

> the same HoA (e.g. HoA-1)?

I think FID can be used to select a specific CoA in case of multiple CoAs 
bound to the same HoA.
Let's focus on the packet forwarding, when HA receive the packet from CN to 
MN(destination address of IP header is HoA), HA will search the binding in 
the BC and select a specific BC entry (different CoA, same HoA) to forward 
the packet according to FID(such as port number, protocol number ).

In your example, FID is bound to a destination address IP-X. IMHO, it's 
useless because FID is used to forward the packet whose destination address 
must be  HoA.

---

From: Gábor Fekete <[email-masked]>
Date: Fri, 26 May 2006 11:31:35 +0300

Hi Andy,

> it's different from the draft.

[snip]

> update the BC entry according to BU, the update process is described in 
OK. So,
preconditions:
o the HA has a (HoA-1, CoA-1) default binding.
  (It does not qualify as a "standard entry", does it? Since it is marked as
   "default".)
event:
o the HA receives a BU for (HoA-1, CoA-1) with FID (dst=IP-X, E set, D not-set)

The draft says in Section 7.3:
  "When the home agent receives a BU which includes at least one Flow
   Identification option, it first performs the operation described in
   section 10.3.1 of RFC3775."
  So, the algorithm jumps to 10.3.1.

RFC 3775 10.3.1:
  "If home agent accepts the Binding Update, it MUST then create a new
   entry in its Binding Cache for this mobile node or update its
   existing Binding Cache entry, if such an entry already exists."
  So, the algorithm updates the (HoA-1, CoA-1) binding.

Later in the draft in Serction 7.3:
  "o  Action = 0: add flow binding.  If the FID in the BU is the same as
      the FID in an existing binding cache entry for the same home
      address, the home agent sends back to the mobile node a BA with a
      error code 136 (FID already in use).  Otherwise, the home agent
      needs to create a new entry in the binding cache with the
      associated flow policies."
  So, the algorithm "needs to create a new entry". But what entry? A new
  binding cache entry or just a Flow Identifier attached/associated to
  the existing entry or a totally new binsing cache entry with HoA set
  to IP-X (assuming IP-X being a HoA that is diferent from HoA-1)?
  (And it is a HA BU, so no Return Routability is needed.)

The draft is quite chaotic to me. It does not clearly define the relation
between Binding Cache entries and Flow Identifiers.
It suggests that Flow Identifiers are managed separately from the
BU in which it was delivered (and in that case, piggybacked). E.g. why
the Dest Addr in the Flow Identifier Option needed? For HMIP? Why?

Section 2 of the draft:
  "Destination Address

      This field identifies the destination address of the data packet
      as seen by the receiver of the binding update.  For a
      correspondent node, the destination is the home address of the
      mobile node.  However, a mobility anchor point would see the
      destination address as the regional care-of address of the mobile
      node.  Hence, the mobile node needs to specify this field as seen
      by the receiver of the binding update."

And Section 6.1 of RFC4140 (HMIPv6), 1st paragraph:
  "After forming the RCoA based on the prefix received in the MAP
   option, the mobile node sends a local BU to the MAP with the A and M
   flags set.  The local BU is a BU defined in [1] and includes the
   mobile node's RCoA in the Home Address Option.  ..."
  So even for BUs to MAPs, this Dest Addr in the Flow Identifier is not
  needed since the HoA is set properly (i.e. to the RCoA) by the
  protocol-obeying HMIPv6 MN.

> the packet according to FID(such as port number, protocol number ).
I think the same but the draft is not clear.

> useless because FID is used to forward the packet whose destination address 
Exactly, it is useless if the draft "works" in the way you and I think.
But if it works in a different way then it makes me wonder if it's just broken
or I just simply don't understand it.

I wonder if the draft authors are planning to release an updated version.

Regards,
Gabor

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From: Andy Huang <[email-masked]>
Date: Fri, 26 May 2006 18:02:36 +0800

Hi, Gabor Fekete:

I agree with you. The draft don't describe it clearly.
IMO,  the point is the content of BC entry. I think BC entry should be 
unique according to (HoA, CoA),  i.e. FID should not exist as a part of BC. 
It works better if FID information can be stored separately.