Re: [6lowapp] the role of gateway nodes

[Carsten Bormann <[e-mail]>]

On Nov 27, 2009, at 15:37, Xavi Vilajosana Guillen wrote:

> what's the approach at 6LowApp? anyone knows ongoing work on that issue?

I would summarize the thinking that went into the BOF as follows:

Some nodes in a CE (constrained environment) may actually be not that constrained (as nodes and with respect to their network).  These can directly speak the appropriate application protocol (HTTP, SNMP, XMPP, SIP) to some correspondent node outside (or inside) the CE.  (We didn't put this on the slides because that is nothing new.)

Some nodes may want to run the constrained application protocol (called CoAP on the BOF slides) right to a correspondent node on the outside.  See the bottom half of slide 13 in http://www.ietf.org/proceedings/09nov/slides/6lowapp-0.pdf as well as the use of CoAP inside the CE (if we had two CEs, this also could be between CEs).

In these two cases, no intermediary (above the IP layer) is involved.

To connect constrained nodes that want to talk CoAP to correspondent nodes outside the CE that want to speak established application protocols, an intermediary is required.  We purposely tried to avoid calling this a gateway, proxy, translator, server, or whatever, because each of these seems to invoke some inappropriate connotations of big hunks of hardware.  Instead we invented the name CoGII (Constrained-node to General Internet Intermediary).  In a 6LoWPAN, this could be the job of a device as simple as an Edge Router, or it could be placed in a quite different position (as CoAP is an Internet-based protocol, there is no restriction on the placement of the CoGII).

Gruesse, Carsten