Subject: [nemo] Text changes to close issue 10

From: Vijay Devarapalli <[email-masked]>
Date: Wed, 06 Aug 2003 11:01:13 -0700

hi all,

I made some significant changes to the text. this is for closing
issue 10. I realised that the Prefix Table and implict mode has 
been a source for lot of confusion. many people dont seem to
like what was intended to be a simple solution. anyway here is
what I propose we should do.

1. use Prefix Table only for verification in explicit mode. it
is used only if the HA needs to be prevent misbehaving MRs from
claiming prefixes that belong to other MRs. if a particular
deployment is such that the HA does not expect MRs to misbehave
then the Prefix Table is not required. 

2. make it clear in Implicit mode that any mechanism can be used.
it is totally internal to the Home Agent. remove all refereces to
using Prefix Table in implicit mode.

3. change Binding Ack status 143 to 'Forwarding Setup failed'. it
is used to indicate that the HA was unable to setup forwarding 
for the Mobile Network when it received a Binding Update from the
MR in implicit mode.

and here the proposed text changes to reflect this. let me
know what you think about these changes.

replace
>       Prefix Table
> 
>               It is a list of a mobile network prefixes indexed
>               by the extended Home Address of a Mobile Router.  The
>               prefix table is managed by the Home Agent.  When a Home
>               Agent receives a Binding Update without any options,
>               it searches a correspondent Mobile Network Prefix in
>               the prefix table, keying with the Home Address of the
>               requesting Mobile Router.  This is an optional data
>               structure.

with 
      Prefix Table
   
              It is a list of a mobile network prefixes indexed
              by the extended Home Address of a Mobile Router.  The
              prefix table is managed by the Home Agent.  This is an
              optional data structure.

replace
>       143     Mobile Network Prefix information unavailable.

with 
        143     Forwarding Setup failed

replace 
>          The Home Agent can use any mechanism (not defined
>          in this document) to determine the Mobile Network Prefix(es)
>          owned by the Mobile Router.  One of the possible mechanisms is
>          where the Home Agent maintains a pre-configured Prefix Table
>          listing all the Mobile Network prefixes owned by a particular
>          Mobile Router.  This table is keyed on the Home Address of the
>          Mobile Router.

with

         The Home Agent can use any mechanism (not defined
         in this document) to determine the Mobile Network Prefix(es)
         owned by the Mobile Router and setup forwarding for the Mobile
         Network.  One example would be manual configuration at the
         Home Agent mapping the Mobile Router's home address to the
         information required for setting up forwarding for the Mobile
         Network.

replace
>    In some scenarios, the Home Agent might need to maintain a Prefix
>    Table of Mobile Routers and the IPv6 prefixes owned by Mobile
>    Routers.  The Home Agent MUST maintain this table if the Mobile
>    Routers operate under the implicit mode where they do not include any
>    prefix information in the Binding Updates.
> 
>    Each entry in the Prefix Table conceptually contains the following
>    fields:
> 
>     -  The Home Address of the Mobile Router.  This field is used as the
>        key for searching the pre-configured prefix table.
> 
>     -  The Mobile Network Prefix of the Mobile Router associated with
>        the Home Address.
> 
>    In some deployment scenarios, it is necessary for Home Agent to
>    prevent a misbehaving Mobile Router from claiming mobile network
>    prefixes belonging to another Mobile Router.  The Home Agent can
>    prevent such attacks if it maintains the Prefix Table and verifies
>    the Prefix Information provided by the Mobile Router against the
>    if the Binding Update contained explicit prefix information in the
>    form of either the Mobile Network Prefix Option or the Mobile Network
>    Prefix Length Option.

with 

   In some deployment scenarios it may be necessary for the Home Agent
   to prevent a misbehaving Mobile Router from claiming mobile network
   prefixes belonging to another Mobile Router.  The Home Agent can   
   prevent such attacks if it maintains the Prefix Table and verifies
   the Prefix Information provided by the Mobile Router against the
   entries in the Prefix Table.  However, this verification is done only
   if the Binding Update contained explicit prefix information in the 
   form of either the Mobile Network Prefix Option or the Mobile Network
   Prefix Length Option.
      
   Each entry in the Prefix Table conceptually contains the following
   fields:

    -  The Home Address of the Mobile Router.  This field is used as the
       key for searching the pre-configured prefix table.

    -  The Mobile Network Prefix of the Mobile Router associated with
       the Home Address.

replace
>     -  If there are no options in the Binding Update, the Home Agent
>        figures out which prefixes are assigned to the Mobile Router
>        from the Pre-configured Prefix Table.  If the Home Agent can not
>        find the correspondent Mobile Network Prefix, it MUST reject the
>        Binding Update and send a Binding Acknowledgement with the Status
>        field set to 143 (Prefix Information unavailable).

to
    -  If there are no options in the Binding Update, the Home Agent
       uses manual pre-configured information to determine the
       prefixes assigned to the Mobile Router and for setting up
       forwarding for the Mobile Network.  If there is no information
       that the Home Agent can use, it MUST reject the Binding Update
       and send a Binding Acknowledgement with status set to 143 
       (Forwarding Setup failed).

replace
>    The Home Agent sets the status code in the Binding Acknowledgement
>    to '143' (Mobile Network Prefix information unavailable) in order
>    to indicate the Mobile Router that the received Home Address in the
>    Binding Update does not match any prefix entry in the pre-configured
>    prefix table.  This is used in the Implicit case where the Mobile
>    Router does not include any prefix information in the Binding Update.

with

   The Home Agent sets the status code to 143 (Forwarding Setup
   failed) if it is unable to determine the information needed to setup
   forwarding for the Mobile Network.  This is used in the Implicit mode
   where the Mobile Router does not include any prefix information in
   the Binding Update.

Vijay

---

From: Vijay Devarapalli <[email-masked]>
Date: Wed, 06 Aug 2003 14:59:37 -0700

> for the Mobile Network when it received a Binding Update from the

and if somebody can come up with something better than
'Forwarding Setup failed', it would be nice. :)

Vijay

---

From: Vijay Devarapalli <[email-masked]>
Date: Wed, 06 Aug 2003 14:59:37 -0700

Vijay

---

From: "Jongkeun Na" <[email-masked]>
Date: Thu, 7 Aug 2003 10:13:11 +0900

It seems to be nice to restrict the use of Prefix Table.
I agree with your proposal. Those of changes make issue 10 as well as
issue 6 clear to me.

/JongKeun

> -----Original Message-----
> From: [email-masked] [mailto:[email-masked]] On Behalf Of
Vijay
> Devarapalli
> Sent: Thursday, August 07, 2003 3:01 AM
> To: [email-masked]
> Cc: [email-masked]
> Subject: [nemo] Text changes to close issue 10
> 
> hi all,
>

---

From: "Jongkeun Na" <[email-masked]>
Date: Thu, 7 Aug 2003 10:13:11 +0900

/JongKeun

Vijay

---

From: Alexandru Petrescu <[email-masked]>
Date: Mon, 11 Aug 2003 15:57:31 +0200

I think that the prefix table concept and its relation to implicit and
explicit modes look much more clearer now.

The minor thing I wish to avoid happening is falsely interpreting
"implicit mode has no Prefix Table" as "implicit is no secure". The
intention is for implicit mode to rely as much as possible on existing
security mechanisms (other than "prefix ownership" induced by Prefix
Table used in explicit mode). But I think this is captured somewhere in
the text; otherwise maybe the security section.

> using Prefix Table in implicit mode.

Sounds good to me.

> for the Mobile Network when it received a Binding Update from the

Good.  I can't think of name alternatives.  Maybe 'Can't Forward'.

>               prefix table is managed by the Home Agent.  This is an

Sounds good.

>          information required for setting up forwarding for the Mobile

Agreed.

>     -  The Mobile Network Prefix of the Mobile Router associated with

Good.

>        uses manual pre-configured information to determine the
               manually

>    where the Mobile Router does not include any prefix information in

Ok.

Alex
GBU

---

From: Alexandru Petrescu <[email-masked]>
Date: Mon, 11 Aug 2003 15:57:31 +0200

Sounds good to me.

Sounds good.

Agreed.

Good.

               manually

Ok.

Alex
GBU