Subject: [Mipshop] Mark Townsley's comments on 4140bis

From: Hesham Soliman <[email-masked]>
Date: Fri, 09 May 2008 13:41:29 +1000

Hi Mark, 

Please see my response to your comment below:

The introduction describes that without the mipshop optimization, MNs have
on average 1.5 signaling round-trips when the node moves... Then makes a
fairly wild leap of conclusion that:

  These round trip delays will
  disrupt active connections every time a handoff to a new AR is
  performed.  Eliminating this additional delay element from the time-
  critical handover period will significantly improve the performance
  of Mobile IPv6. 

What connections are being disrupted for each and every AR?

=> The connections are not for the ARs, these are the mobile node's
connections with other CNs. The connections are disrupted upon movement
between Ars of course due to the lag in re-routing caused by the RTT between
the MN and HA or MN and CN in case of RO.

  Also, I see no analysis here that shows that there will be a significant
  performance improvement to the Mobile IPv6 user.

=> I'm not sure what analysis is needed, the numbers are clear. I can add
references to publications if you like but I think it is clear that one BU
is less than many and that sending the BU to a local router will take less
time than sending it to a remote HA.

 There is language in this document stating the optional nature of this
 feature, but if the above claims are true then I cannot see how this could
 be optional. So, the document is rather inconsistent here.

=> It's an optimisation. MIPv6 still works without HMIPv6, but with HMIP it
works better. I don't think we need something like HMIP to be mandatory.
People might not need it in their deployments.

Hesham

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