Hi!

 
During the analysis of the handover latency of MIPv6, I got a confused question.
 
A normal MIPv6 handover process is as follows:
 
1.[movement Detection]  --> 2.[Router Discovery] --> 3.[Address Congifuration]-->4.[DAD]-
->5.[HA Registration]-->6.[CN Registration]
The first four componets are with no problems. So hier I just focus the last two components.
 
The HA registration (the MN CoA registed to HA) time is defined as the transmission delay incurred during registration of the MN CoA with its HA. It begins from the MN sends BU to its HA until the MN receives the BA sent by HA.
 
And then, the MN must start the Return Routability Procedure (RRP) before it sends a BU to CN.That is, the MN must first initiate the Home Test (HoT) and Care-of Test before it can send a BU to CN.
 
But I observed from the package information catched by ethereal, there was always a time delay between the BA sent by HA and HoT (the start of RRP), one example is shown below:
 
*fe80::202:2dff:fe07:9948 is the IPv6 address of the new Access Router (AR),
 2001:106:1200::2 is the Home Address of MN
 2001:106:1200::1 is the address of the HA
 2001:106:2600::2 is CN's address
 2001:106:1100:0:204:23ff:fe5f:163e is MN's CoA when it left its homenet and moved to a visitnet.
 
========================================================================================
1. Seq.    time         Sorce Address        Distination Address      
-----------------------------------------------------------------------------------------
    ....
   2243 114.215153  fe80::202:2dff:fe07:9948 ff02::1        ICMPv6   Router advertisement
   2244 114.275060  fe80::202:2dff:fe07:9948 ff02::1        ICMPv6   Router advertisement
   2245 114.331100  fe80::202:2dff:fe07:9948 ff02::1        ICMPv6   Router advertisement
   2246 114.367109  fe80::202:2dff:fe07:9948 ff02::1:ff5f:163e     ICMPv6   Neighbor solicitation
   2247 114.367168  2001:106:1100:0:204:23ff:fe5f:163e fe80::202:2dff:fe07:9948 ICMPv6   Neighbor advertisement
   2248 114.369291  2001:106:1200::1      2001:106:1100:0:204:23ff:fe5f:163e MIPv6    Binding Acknowledgement  (BA sent by HA to MN)
---------------------------------------------------------------------------------------
   2249 114.395042  fe80::202:2dff:fe07:9948 ff02::1       ICMPv6   Router advertisement
   2250 114.451152  fe80::202:2dff:fe07:9948 ff02::1       ICMPv6   Router advertisement
   2251 114.503107  fe80::202:2dff:fe07:9948 ff02::1       ICMPv6   Router advertisement
   2252 114.556071  fe80::202:2dff:fe07:9948 ff02::1       ICMPv6   Router advertisement
   2253 114.623126  fe80::202:2dff:fe07:9948 ff02::1       ICMPv6   Router advertisement
   2254 114.667084  fe80::202:2dff:fe07:9948 ff02::1       ICMPv6   Router advertisement
   2255 114.677178  2001:106:1200::2      2001:106:2600::2      ICMPv6   Echo request
   2256 114.680095  2001:106:2600::2      2001:106:1200::2      ICMPv6   Echo reply
----------------------------------------------------------------------------------------
   2257 114.681259  2001:106:1200::2      2001:106:2600::2      MIPv6    Home Test Init(RRP start)
   2258 114.681454  2001:106:1100:0:204:23ff:fe5f:163e 2001:106:2600::2      MIPv6    Care-of Test Init
   2259 114.684111  2001:106:2600::2      2001:106:1200::2      MIPv6    Home Test
   2260 114.686225  2001:106:2600::2      2001:106:1100:0:204:23ff:fe5f:163e MIPv6    Care-of Test
   2261 114.686647  2001:106:1100:0:204:23ff:fe5f:163e 2001:106:2600::2      MIPv6    Binding Update
   2262 114.689347  2001:106:2600::2      2001:106:1100:0:204:23ff:fe5f:163e MIPv6    Binding Acknowledgement  (Handover completed)

============================================================================================

As shown in the above table, a delay of 0.32s is caused by the blue colored RAs sent by the AR and also ICMPv6 Echo request and reply between the BA sent by the HA and the start of RRP. And some other tests even got a worse delay time than this.

What is this delay? Which fators are possible to cause this delay? Anyone has idea about it?

Any suggestion will be very appreciated!

Tian

 


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