Subject: [Roll] Comments on Route-Tags - RPL Version 10 - WG LC

From: JP Vasseur <[email-masked]>
Date: Fri, 16 Jul 2010 09:09:58 +0200

Dear all,

One comment:

8.2.  Downward Route Discovery and Maintenance

    Destination Advertisement may be configured to be entirely disabled,
    or operate in either a storing or non-storing mode, as reported in

Winter, et al.          Expires December 30, 2010              [Page 62]

Internet-Draft           draft-ietf-roll-rpl-10                 Jun 2010

    the MOP in the DIO message.

    1.  All nodes who join a DODAG MUST abide by the MOP setting from  
the
        root.  Nodes that do not have the capability to fully  
participate
        as a router MAY join the DODAG as a leaf.
    2.  If the MOP is 000, indicating no downward routing, nodes MUST  
NOT
        transmit DAO messages, and MAY ignore DAO messages.

    3.  In non-storing mode, the DODAG Root MUST store source routing
        table entries for all destinations learned from DAOs.
JP> I do not think that I would mandate for "all destinations", it  
could be for a subset
according to some policy (remember the route tag ?).
At some point we had the possibility to add tags to route (to indicate  
a priority, etc, ...).
Note extensively used in other routing protocols too. Don't you think  
that it would be wise
adding them back (this is a simply field of flags).

Thoughts ?

---

From: "Pascal Thubert (pthubert)" <[email-masked]>
Date: Fri, 16 Jul 2010 12:16:45 +0200

Hi JP:

JP> I do not think that I would mandate for "all destinations", it could
be for a subset 
according to some policy (remember the route tag ?).

[Pascal] The problem is that we do not know a priori whether a target is
also a parent since that comes in another DAO. If it is a parent then we
need to store it to be able to build the source route path to and via
its children. If the root now has a policy to refuse a DAO, then it
needs to indicate so in the DAO Ack so that the node can branch
elsewhere. All this process including err codes would have to be
documented. At the moment we expect that the network is dimensioned  and
operated in such a fashion that the root can accept all nodes that are
able to join.

JP> At some point we had the possibility to add tags to route (to
indicate a priority, etc, ...).
Note extensively used in other routing protocols too. Don't you think
that it would be wise 
adding them back (this is a simply field of flags).

[Pascal] I'd love it. The thing is that the tag is used by the parent to
indicate the next hop. Usually it is locally significant to the parent.

At the moment, the child indicates its parents in the DAO but wouldn't
know the tag that the parent would affect to it.

If we're taking the path of tagging, then we might need a flow to get
the tag from the parent, for instance using an ND extension. 

As the parent learns about the child and creates an NC Entry, it also
assigns a tag associated to that Neighbor, and passes it to the child as
a source or target tag option depending on the ND message being used.

For RPL, all we'd need to do is enable the tagging by adding room for a
tag to the transit option. I'm really positive.

Votes?. 

Pascal

From: [email-masked] [mailto:[email-masked]] On Behalf Of
JP Vasseur
Sent: Friday, July 16, 2010 9:10 AM
To: ROLL WG
Subject: [Roll] Comments on Route-Tags - RPL Version 10 - WG LC

Dear all,

One comment:

 

 
   1.  All nodes who join a DODAG MUST abide by the MOP setting from the
       root.  Nodes that do not have the capability to fully participate
       as a router MAY join the DODAG as a leaf.
   2.  If the MOP is 000, indicating no downward routing, nodes MUST NOT
       transmit DAO messages, and MAY ignore DAO messages.
 
   3.  In non-storing mode, the DODAG Root MUST store source routing
       table entries for all destinations learned from DAOs.
JP> I do not think that I would mandate for "all destinations", it could
be for a subset 
according to some policy (remember the route tag ?).
At some point we had the possibility to add tags to route (to indicate a
priority, etc, ...).
Note extensively used in other routing protocols too. Don't you think
that it would be wise 
adding them back (this is a simply field of flags).
 
Thoughts ?

---

From: JP Vasseur <[email-masked]>
Date: Fri, 16 Jul 2010 16:47:30 +0200

oops ! I think that we're not talking about the same thing.

By "tag" I was referring to route-tag not tags for label switching:  
something we may want to work on at some point BUT we would need to  
revisit our charter. Something we'll bring to the list soon, after the  
RPL LC, OK ?

I was referring to using route-tags as a flag field to color the route  
if you will.

Thoughts ?

On Jul 16, 2010, at 12:16 PM, Pascal Thubert (pthubert) wrote:

> [Pascal] The problem is that we do not know a priori whether a  
> target is also a parent since that comes in another DAO. If it is a  
> parent then we need to store it to be able to build the source route  
> path to and via its children. If the root now has a policy to refuse  
> a DAO, then it needs to indicate so in the DAO Ack so that the node  
> can branch elsewhere. All this process including err codes would  
> have to be documented. At the moment we expect that the network is  
> dimensioned  and operated in such a fashion that the root can accept  
> all nodes that are able to join.
>
> Note extensively used in other routing protocols too. Don't you  
> think that it would be wise
> [Pascal] I’d love it. The thing is that the tag is used by the  
> parent to indicate the next hop. Usually it is locally significant  
> to the parent.
> At the moment, the child indicates its parents in the DAO but  
> wouldn’t know the tag that the parent would affect to it.
>
> If we’re taking the path of tagging, then we might need a flow to  
> get the tag from the parent, for instance using an ND extension.
> As the parent learns about the child and creates an NC Entry, it  
> also assigns a tag associated to that Neighbor, and passes it to the  
> child as a source or target tag option depending on the ND message  
> being used.
>
> For RPL, all we’d need to do is enable the tagging by adding room  
> for a tag to the transit option. I’m really positive.
>
> Votes?.
>
> Pascal
>
> From: [email-masked] [mailto:[email-masked]] On Behalf  
> Of JP Vasseur
> At some point we had the possibility to add tags to route (to  
> Note extensively used in other routing protocols too. Don't you  
> think that it would be wise