Subject: [Roll] New link-local RPL multicast address and 6lowpan-HC

From: Joakim Eriksson <[email-masked]>
Date: Wed, 14 Jul 2010 12:15:48 +0200

Hello,

The new RPL all routers address ff02::1:a is going to cause much worse 
compression (3 bytes vs 1 byte) of the destination address in 6lowpan
based networks. Is there any plans for "fixing" the HC or are we ok with
this? (I like small messages ;-)

Would it be impossible to get a ff02::1a address from IANA instead?

Best regards
-- Joakim Eriksson, SICS

---

From: "Alexander, Roger" <[email-masked]>
Date: Wed, 14 Jul 2010 16:02:20 -0400

Hi WG,

I would like to recommend use of a DODAG-defined Default Path Lifetime
as opposed to the current model in which Path Lifetime is specified per
prefix using the Transit Information Option. 

As in other routing protocols, such as RIP for example, the validity
period of an advertised prefix is defined not per destination address
but is specified through a protocol configuration element such as the
route-timeout timer. In the same vein, a default validity period can be
defined for all advertised destinations through a Default Path Lifetime
specified within the DODAG Configuration option. This default value will
apply to all advertised prefixes unless otherwise specified using an
optional Path Lifetime information element within the Transit
Information option. The benefit of a Default Path Lifetime is that it
will allow 4-bytes to be saved per advertised DAO destination unless a
specific, dedicated Path Lifetime is needed for a given prefix. The
Lifetime for a destination address will continue to apply from the time
of receipt at a node.

No additional control bits will be required within the Transit
Information Option as the presence or absence of the Path Lifetime
information element can be directly deduced from the value of the Option
Length. 

Thanks.

Roger

---

From: Daniel Gavelle <[email-masked]>
Date: Thu, 15 Jul 2010 09:37:08 +0100

Alexander,

I think this is a good idea.  The number of nodes on a network may well 
be limited by the memory available to store the per-node information on 
the root.

Daniel.

Alexander, Roger wrote:
> _______________________________________________
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> 

-- 
__________________________________________________
Daniel Gavelle, Software Engineer
Tel: +44 114 281 2655
Fax: +44 114 281 2951
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__________________________________________________

---

From: "Pascal Thubert (pthubert)" <[email-masked]>
Date: Thu, 15 Jul 2010 11:38:19 +0200

Great point Joakim; 

1A is actually free in
http://www.iana.org/assignments/ipv6-multicast-addresses/ 
let's try and get that value?

Pascal

> -----Original Message-----
> From: [email-masked] [mailto:[email-masked]] On Behalf
Of
> Joakim Eriksson
> Sent: Wednesday, July 14, 2010 12:16 PM
> To: roll
> Subject: [Roll] New link-local RPL multicast address and 6lowpan-HC
> 
> Hello,
> 
based
> networks. Is there any plans for "fixing" the HC or are we ok with
this? (I like
> small messages ;-)

---

From: Joakim Eriksson <[email-masked]>
Date: Thu, 15 Jul 2010 18:32:02 +0200

Exactly, it is free, and is a good replacement for 1:a!
And, yes, we should take it if we can!

Best regards,
-- Joakim Eriksson, SICS

---

From: "Pascal Thubert (pthubert)" <[email-masked]>
Date: Fri, 16 Jul 2010 15:53:52 +0200

Advice to all : )

The requested mcast address for RPL will be FF02::1A as opposed to
FF02::1:A
If you see a problem with that value please let us now.
If you plan interop tests please use this new value.

" This specification requires the  allocation of a new permanent
multicast address with a link local  scope for RPL routers, with a
suggested value of FF02::1A, to be confirmed by IANA."

Cheers,

Pascal

> From: Joakim Eriksson [mailto:[email-masked]]
> Sent: Thursday, July 15, 2010 6:32 PM
> To: Pascal Thubert (pthubert)
> Cc: roll
> Subject: Re: [Roll] New link-local RPL multicast address and
6lowpan-HC
> >> The new RPL all routers address ff02::1:a is going to cause much
> >> worse compression (3 bytes vs 1 byte) of the destination address in
> >> 6lowpan
> > based