Subject: [6lowpan] RL2N BOF in Vancouver

From: JP Vasseur <[email-masked]>
Date: Fri, 26 Oct 2007 14:31:36 -0400

Dear list,

The RL2N BOF has been approved for Vancouver.

I've updated www.employees.org/~jvasseur with the related information  
- please provide
your comments.

We're planning to have a pre-WG meeting in Boston Nov 15 with 15-20  
people
who expressed some interest in this work. Let us know if you would  
like to attend.
Otherwise, we will post the minutes of that meeting on the list.

Thanks.

JP.

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6lowpan mailing list
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https://www1.ietf.org/mailman/listinfo/6lowpan

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From: Kris Pister <[email-masked]>
Date: Mon, 29 Oct 2007 10:38:34 -0700

JP - the RL2N charter looks good.  My only concern is over the second L 
in L2 - are these networks intrinsically lossy, or is that just due to 
the current protocols?

I'll be at the meeting in Boston.

Question about Vancouver: I've never been to an IETF meeting before.  
Are there any important rules/regs that a newbie should know before 
attending?  The IEEE has lots...
Related question: what day(s)/time(s) should we plan on attending?

ksjp

JP Vasseur wrote:
> RSN mailing list
> [email-masked]
> https://www1.ietf.org/mailman/listinfo/rsn

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From: Philip Levis <[email-masked]>
Date: Mon, 29 Oct 2007 10:54:19 -0700

On Oct 29, 2007, at 10:38 AM, Kris Pister wrote:

> JP - the RL2N charter looks good.  My only concern is over the  
> second L in L2 - are these networks intrinsically lossy, or is that  
> just due to the current protocols?

The "lossy" means at the link layer. There aren't any wireless link  
layers that don't have losses. They might mask them to higher layers  
through retransmissions, but losses occur. Of course, a network layer  
may select links that have a very low loss rate, but, well, that's  
part of what all of this effort is about.

Phil

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From: "Chevrollier, N.G. (Nicolas)" <[email-masked]>
Date: Mon, 29 Oct 2007 18:59:40 +0100

HI JP,

Could you give an example of L2Ns in "smart cities"? I am not sure to
get what it encompasses.

Best,

Nicolas

> -----Original Message-----
> From: JP Vasseur [mailto:[email-masked]]
> Sent: Friday, October 26, 2007 8:32 PM
> To: [email-masked]
> Cc: 6lowpan
> Subject: [RSN] RL2N BOF in Vancouver
> 
> Dear list,
> 

This e-mail and its contents are subject to the DISCLAIMER at http://www.tno.nl/disclaimer/email.html

---

From: Kris Pister <[email-masked]>
Date: Mon, 29 Oct 2007 11:30:37 -0700

Hmm.  You could probably make the claim that there aren't any wired link 
layers that don't have losses, too.  I guess that it's all relative.  
What are the loss rates in wired systems?
Certainly it is possible to find path/channel combinations in 802.15.4 
networks that have zero loss at the link layer over periods of many 
weeks and millions of packets, which I think gets called "carrier class" 
reliability. 
If we're smart, we'll be able to build networks that use such 
path/channel combos almost exclusively.  As you point out, this is a 
DLL/MAC issue, so its solution doesn't belong in this forum (that's what 
the 15.4E task group was created to address).  But the abstraction does 
belong here, and it's important to understand what's really going on in 
15.4 (and other RF) channels to make intelligent routing decisions on 
them. 
To date most of the published WSN channel models have interpreted abrupt 
multi-path interference as a lossy path, and that will lead to bad 
decisions at the routing layer.

ksjp

Philip Levis wrote:
>> JP - the RL2N charter looks good.  My only concern is over the second 
>> L in L2 - are these networks intrinsically lossy, or is that just due 
>> to the current protocols?
>

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From: Kris Pister <[email-masked]>
Date: Mon, 29 Oct 2007 11:33:55 -0700

I don't know if this is what JP's thinking about, but this is a cool 
company:

http://www.StreetlineNetworks.com

ksjp

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From: Philip Levis <[email-masked]>
Date: Mon, 29 Oct 2007 17:14:00 -0700

On Oct 29, 2007, at 11:30 AM, Kris Pister wrote:

> Hmm.  You could probably make the claim that there aren't any wired  
> link layers that don't have losses, too.  I guess that it's all  
> relative.  What are the loss rates in wired systems?

The point is relative; losses of course exist in wired systems. A lot  
of it boils down to assumptions; if line loss rates are such that  
most losses are due to congestion, you want different rate control  
than if they are link losses. The many efforts to get TCP working on  
wireless, as well as high-speed TCP and fast TCP are some of the  
major examples.

> Certainly it is possible to find path/channel combinations in  
> 802.15.4 networks that have zero loss at the link layer over  
> periods of many weeks and millions of packets, which I think gets  
> called "carrier class" reliability.

It's important to note that this only applies for particular  
topologies and environments. Zero loss at the link layer over periods  
of weeks is unlikely if you're next to a microwave. It's the edge  
cases that always get you.

> If we're smart, we'll be able to build networks that use such path/ 
> channel combos almost exclusively.

I think I might word it slightly differently: if we're smart, we'll  
be able to build networks that detect such path/channel combinations  
when they exist. Assuming they always exist seems dangerous to me.

Phil

---

From: JP Vasseur <[email-masked]>
Date: Tue, 30 Oct 2007 11:48:50 -0400

The point is indeed to specify routing protocol for networks  
comprising constrained devices
( e.g. low power) interconnected via lossy links/nodes since indeed  
the node failure rate is
likely to be higher than in typical IP networks.

Cheers.

JP.

On Oct 29, 2007, at 8:14 PM, Philip Levis wrote:

>> Hmm.  You could probably make the claim that there aren't any  
>> wired link layers that don't have losses, too.  I guess that it's  
>> all relative.  What are the loss rates in wired systems?
>
> The point is relative; losses of course exist in wired systems. A  
> lot of it boils down to assumptions; if line loss rates are such  
> that most losses are due to congestion, you want different rate  
> control than if they are link losses. The many efforts to get TCP  
> working on wireless, as well as high-speed TCP and fast TCP are  
> some of the major examples.
>
>
> topologies and environments. Zero loss at the link layer over  
> periods of weeks is unlikely if you're next to a microwave. It's  
> the edge cases that always get you.
>
> be able to build networks that detect such path/channel  
> combinations when they exist. Assuming they always exist seems  
> dangerous to me.
>
> Phil
>
>

---

From: JP Vasseur <[email-masked]>
Date: Tue, 30 Oct 2007 16:06:12 -0400

Hi Kris,

On Oct 29, 2007, at 1:38 PM, Kris Pister wrote:

> Question about Vancouver: I've never been to an IETF meeting  
> before.  Are there any important rules/regs that a newbie should  
> know before attending?  The IEEE has lots...

I'll send you some data off-line.

> Related question: what day(s)/time(s) should we plan on attending?

This will be known on November 12. I'll send a note to the ML.

Cheers.

JP.

>> I've updated www.employees.org/~jvasseur with the related  
>> information - please provide
>> your comments.
>>
>> We're planning to have a pre-WG meeting in Boston Nov 15 with  
>> 15-20 people