Subject: RE: [Mip4] HA=0.0.0.0 question (HA Discovery)

From: "Kent Leung \(kleung\)" <[email-masked]>
Date: Tue, 19 Jul 2005 10:51:41 -0700

Hi George.

In RFC 3344, section 3.6.1.2:

   The Home Agent field MUST be set to the address of the mobile node's
   home agent, if the mobile node knows this address.  Otherwise, the
   mobile node MAY use dynamic home agent address resolution to learn
   the address of its home agent.  In this case, the mobile node MUST
   set the Home Agent field to the subnet-directed broadcast address of
   the mobile node's home network...

There is no explicit specification on how FA should deal with HA field
that is 0.0.0.0.  So let's find out what can be implemented?

1) FA forward the RRQ as specified in RFC 3344.  This means that the
dest IP addr of the RRQ will be set to the HA field.  Scenario covered
in draft as "Legacy foreign agents may forward ...".

2) FA sends reject RRP to MN, as mentioned by you.

I don't think there are any other possibilities.  If so, here's the new
amended text:

draft-ietf-mip4-dynamic-assignment-04.txt, section 10:

2. If the MN does not receive a Registration Reply within some time 
     and/or after sending a few Registration Requests, it can assume 
     that the Registration Request(s) has been dropped, either by a 
     legacy FA or an incorrect HA.  In addition, if the registration is 
     denied with error code 70 (poorly formed Request), the MN can
assume
     that the legacy FA cannot process this message.  In either case,
     the MN should fall back to a 
     recovery mechanism.  The MN should quickly send a new Registration 
     Request as mentioned in section 4.1 step 2.  This step will ensure 
     that a legacy FA will forward the Registration Request to the Home 
     Agent thereby making dynamic HA assignment possible. 

Is this OK?

Kent 

> -----Original Message-----
> From: [email-masked] [mailto:[email-masked]] On 
> Behalf Of Tsirtsis, George
> Sent: Monday, July 18, 2005 12:12 PM
> To: Pete McCann; Ranjitsinh Wable
> Cc: [email-masked]
> Subject: RE: [Mip4] HA=0.0.0.0 question (HA Discovery)
> 
> Hi everyone....have not been here for a while....
> 
> I think the paragraph quoted below should be removed from the 
> draft since it is not possible to suggest what "legacy" 
> equipment need to do in addition to what the already do. One 
> can only observe what the reaction of an existing 
> implementation might be based on the legacy specification.
> 
> A legacy FA will probably support just what is in RFC3344, 
> which does not include the idea of HA==0. I would guess that 
> such an FA might just return a RREP with Code==70 "poorly 
> formed Request".
> 
> Regards
> George
> 
> > -----Original Message-----
> > From: [email-masked] [mailto:[email-masked]] 
> On Behalf 
> > Of Pete McCann
> > Sent: Monday, July 18, 2005 10:37 AM
> > To: Ranjitsinh Wable
> > Cc: [email-masked]
> > Subject: [Mip4] HA=0.0.0.0 question (HA Discovery)
> > 
> > 
> > 
> > Hi,
> > 
> > The use of ALL-ZERO-ONE-ADDR for the HA address is specified in 
> > draft-ietf-mip4-dynamic-assignment-04.txt.  This may be a good 
> > opportunity to remind the group that we should still be 
> discussing the 
> > resolution of Thomas Narten's comment on this draft, namely:
> > 
> > > >    Legacy Foreign Agent:
> > > >   
> > > >    Legacy foreign agents may forward a Registration
> > Request with home
> > > >    agent field set to ALL-ZERO-ONE-ADDR by setting the
> > destination IP
> > > >    address to ALL-ZERO-ONE-ADDR.  This will result packet
> > being dropped
> > > >    or incidentally handled by a next hop HA, adjacent to
> > the FA.   
> > > 
> > > hmm. how does one distinguish network connectivity problems
> > from "not
> > > implemented"? I.e, what recovery action does a MN take in this 
> > > situation?
> > 
> > We have had some discussion on this but I am not sure we reached a 
> > final conclusion.
> > 
> > -Pete
> > 
> > 
> > Ranjitsinh Wable writes:
> >  > Hi all,
> >  >
> >  > Here I am having small question regarding the MIPv4.
> >  > Few days back on the mailing list I saw the discussion  
> > about the 
> > HoA being 0.0.0.0 but what if the HA address  > itself is zero. RFC 
> > 3344 does not talk about this case.
> >  > It talks about the dynamic HA discovery using the  > subnet 
> > broacast messages.
> >  >
> >  > What if the HA address in the RRQ is 0.0.0.0.
> >  > Is it the same procedure to resolve the HA address  > 
> using NAI of 
> > the MN and AAA server?
> >  >
> >  > Is there any standard stating the use of NAI of MN  > to resolve 
> > the HA of MN.
> >  >
> >  > Thanks in advance.
> >  >
> >  > Regards,
> >  >
> >  > Wable R. U.
> > 
> > 
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