MIH commands for handover

[Sanjib Das <Sanjib.Das@lntinfotech.com>]

Handover Using MIH Messages:
a) Predictive Mode:

Explanation of above depicted
flow:

MN can generate the NCoA from the
available prefix info (from IS Server).

1. For initiating the handover
MN sends MIH_MN_HO_Candidate_Query.Request
query to PAR. As per the draft
(version 4) MN sends following information in this command.

MIH_MN_HO_Candidate_Query.request
(
DestinationIdentifier,
CurrentLinkIdentifier,
CandidateLinkList,
QueryResourceList,
CandidatePoAList
)

But once the request query is received
by PAR it needs to send the 
MIH_N2N_HO_Query_Resources.Request
to NAR. But in Candidate query
the MN never sends NAR’s IP address. Now there are two ways to get the
NAR’s IP address.
PAR can query the IS Server for
NAR’s address using CandidatePoA address as the key. But this method can
increase the latency. But this brings out a scenario where IS Handler in
ACR/AR can exist.

MN should send the NAR’s address
(as it can get it from IS Server) to PAR, 
so that Resource Query can be send
easily. In this approach, one more parameter should be added into the Candidate
query request message.

2. Once the PAR gets MIH_N2N_HO_Query_Resources.Confirm
, it needs to create the tunnel
for sending all the packets to NAR (until the handover is over). But for
creating the tunnel, PAR should have the NCoA of MN & PAR in turn should
send the NCoA to NAR for duplicity checking. This is analogous to FBU &
FBack mechanism of FMIPv6.

3. As per the above discussed point,
the candidate Query should contain two more parameters. 

MIH_MN_HO_Candidate_Query.request
(
DestinationIdentifier,
CurrentLinkIdentifier,
CandidateLinkList,
QueryResourceList,
CandidatePoAList,
CandidateNwAddrList,
       /*Access router’s addresses*/
MN_NCoAList,  
                 /*List
of NCoA as per Target n/w prefix*/
)
MN_NCoA should be there in both
MIH_N2N_HO_Query_Resources.Request
 & MIH_N2N_HO_Query_Resources.Response
 messages also.

NAR should verify the New CoA for
duplicity. 
If the NAR is an ACR, then it can
check the New Address against its list of MN’s addresses (This list is
maintained by the ACR).
In case of AR also the same method
can be adopted.

MIH_N2N_HO_Query_Resources.Response
should contain MN’s confirmed NCoA along with requested resource list.
Once the Response message is received, PAR should create the tunnel now.

MIH_MN_HO_Candidate_Query.Response
should contain MN’s confirmed
NCoA &  the requested resource list.

L2 connection is established with
target link.

1. This is analogous to FMIPv6
FNA message. This should initiate sending all buffered packets in NAR (which
it received over tunnel from PAR) to MN. As per the definition in draft,
MN sends following parameters in request message. 

MIH_MN_HO_Complete.request (
         
      DestinationIdentifier,
LinkIdentifier,
HandoverStatus
)

Once this is received by NAR, it
should inform PAR for closing the tunnel & flushing all the information
for that MN. This can be done using the message MIH_N2N_HO_Complete (Network<->Network).


MIH_N2N_HO_Complete.request (
DestinationIdentifier,
MNIdentifier,
CurrentLinkIdentifier,
HandoverStatus
)

But this message does not include
the PAR’s IP address. So it is MN’s job to send the PAR’s address in
MIH_MN_HO_Complete.request message, which in turn can be used by NAR for
sending MIH_N2N_HO_Complete request to PAR.

There can be one more parameter
in MIH_N2N_HO_Complete request message.

MIH_MN_HO_Complete.request (
         
      DestinationIdentifier,
LinkIdentifier,
HandoverStatus,
PreviousARAddress  
     /*PAR’s IP Address*/
)




Please Comment

thanks & regards
Sanjib

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