Subject: Re: [mobile-ip] Mipv6 issue #245: prefix fetching intervals

From: "Sourajeet Mohanty" <[email-masked]>
Date: Wed, 19 Feb 2003 14:37:29 +0530

o  If the mobile node has not received the prefix information within
       the last MaxMobPfxAdvInterval (see Section 13) seconds, then
       ensure that a transmission is scheduled. The actual transmission
       time is randomized as described below.

Does this mean that Home Agent has to start sending unsolicited MPAs
periodically at every MaxMobPfxAdvInterval to the Mobile Node after
successful registration with Home Agent ?

----------------------------------------------------------------
Sourajeet Mohanty
Software Engineer
Communications and Embedded Systems
L&T Infotech Ltd., Bangalore
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                      Jari Arkko                                                                                  
                      <[email-masked]>        To:       Ville Nuorvala <[email-masked]>,    
                      Sent by:                         [email-masked], "T.J. Kniveton"         
                      owner-mobile-ip@sunroof.         <[email-masked]>                               
                      eng.sun.com                     cc:       "[email-masked]'"                 
                                                       <[email-masked]>                            
                                                      Subject:  Re: [mobile-ip] Mipv6 issue #245: prefix fetching 
                      17/02/2003 08:35 PM              intervals                                                  

Jari Arkko wrote:

> Here's one possible approach to fix the current mess with the
advertisement
> intervals:
>
> 1. Relax the rules for mobile nodes regarding the exact timing of
>    sending MPS messages. There does not appear to be a reason to
>    require more exact timing than doing it well in advance of the
>    prefix being deprecated.
>
>    If we do this, we will also avoid the need to send any unsolicited
>    MPA timing parameters from the home agent to the mobile node. And
>    we will avoid the MaxRtrAdvInterval / MaxMobPfxAdvInterval problem,
>    as well as get rid of MAX_PFX_ADV_DELAY.
>
>    In any case, the home agent is in the best position to select the
>    right frequency based on expected changes in prefixes. Also, the
>    lifetimes of prefixes sent through MPA will force the mobile nodes
>    to update their information at some point.
>
> 2. Remove HomeRtrAdvInterval and just use MaxMobPfxAdvInterval
>    instead.
>
> 3. Make it clear that all unsolicited MPAs are under the same timing
>    randomization rules. Solicited MPAs are sent immediately.

Here's the text proposal related to the above solution:

Changed contents in Section 10.6.2:

    10.6.2 Scheduling Prefix Deliveries

    ...

    The home agent uses the following algorithm to determine when to send
    prefix information to the mobile node.

    o  If a mobile node sends a solicitation, answer right away.

    o  If the mobile node has not received the prefix information within
       the last MaxMobPfxAdvInterval (see Section 13) seconds, then
       ensure that a transmission is scheduled. The actual transmission
       time is randomized as described below.

    o If a prefix in the aggregate list that matches the mobile node's
       home registration is added, or if its information changes in any
       way that does not cause the mobile node's address to go
       deprecated, ensure that a transmission is scheduled. The actual
       transmission time is randomized as described below.

    o  If a home registration expires, cancel any scheduled
       advertisements to the mobile node.

    ...

New contents of Section 11.4.2:

    11.4.2 Sending Mobile Prefix Solicitations

    When a mobile node has a home address that is about to become
    invalid, it SHOULD send a Mobile Prefix Solicitation to its home
    agent in an attempt to acquire fresh routing prefix information.
    The new information also enables the mobile node to participate in
    renumbering operations affecting the home network, as described in
    Section 10.6.

    The mobile node MUST use the Home Address destination option to carry
    its home address.  The mobile node MUST support and SHOULD use IPsec
    to protect the solicitation.  The mobile node MUST set the Identifier
    field in the ICMP header to a random value.

    As described in Section 11.7.2, Binding Updates sent by the mobile
    node to other nodes MUST use a lifetime no greater than the
    remaining ...

New contents of Section 13:

    13. Protocol Configuration Variables

      MaxMobPfxAdvInterval            Default: 86,400 seconds
      MinDelayBetweenRAs              Default: 3 seconds,
                                      Min: 0.03 seconds
      MinMobPfxAdvInterval            Default: 600 seconds
      InitialBindackTimeoutFirstReg   Default: 1.5 seconds

    Home agents MUST allow the first three variables to be configured
    by system management, and mobile nodes MUST allow the last variable
    to be configured by system management. ...

---

From: Jari Arkko <[email-masked]>
Date: Wed, 19 Feb 2003 14:36:48 +0200

> successful registration with Home Agent ?

We changed the formulation of this bullet item a bit. But essentially
the answer is yes -- thought there's some randomness involved in the
time period. Note that MaxMobPfxAdvInterval is a variable i.e. it
can be set by system management to another value.

Jari