Subject: [6lowpan] backbone router and scalability

From: "Pascal Thubert (pthubert)" <[email-masked]>
Date: Wed, 11 Aug 2010 17:21:45 +0200

Hi :

At the meeting there was the question about the scalability that the
backbone router provides.

I can add a few words on that. I'd suggest text along the following
lines:

-          In some cases, the scalability we are looking for is simply
geographical, extending the LoWPAN over a large space. The backbone can
interconnect localized LLNs into a larger one.

-          In other cases, we want to allow more nodes in the network,
and avoid the need to notify all LBRs of all addresses by distributing
the white board over the backbone. The number of nodes that the Backbone
router allows is basically limited by the capability of the backbone,
which varies a lot between a WIFI mesh and a 10+Ge TRILL infrastructure.

What we can say on the positive side is that:

-          The traffic usually converges to a limited set of routers on
the backbone. Those will have to manage large neighbor caches. But
considering the type of traffic, most other nodes on the backbone will
have small caches, and that illustrates that the traditional reactive ND
over the backbone is more efficient for our needs than a proactive
routing protocols that would force all BBRs to know all devices in the
networks.

-          The backbone routers can throttle the ND traffic for their
devices so the traffic will be smoother than with a same number of
devices really connected to the backbone.

-          The devices are battery operated so you do not have an effect
like a brutal power on of all nodes.

Do I miss anything?

Pascal