Re: sketchy laugh test: device discovery BOF

["James Kempf" <kempf@docomolabs-usa.com>]

So I'm a little unclear where the boundary between device discovery and
service discovery lies. Maybe because I haven't read 802.1ab.

The reason why I am somewhat suspicious on this is because the Bluetooth SIG
essentially took SLP and put it into Layer 2, making their specification
lots more complicated than it needed to be. I don't know if that carried
over into 802.15 or not, but it raises a note of caution in my mind when I
read about device discovery in groups doing link layer protocols. I think
there is a link layer role for device discovery, but when it involves
attributes (as, apparently, 802.1ab does from your description below), it
seems like it might be shading over into service discovery.

Perhaps the intent of the BOF is to sort out these issues?

            jak

----- Original Message ----- 
From: "Bernard Aboba" <bernard_aboba@hotmail.com>
To: <narten@us.ibm.com>; <iab@iab.org>; <iesg@ietf.org>
Sent: Wednesday, June 18, 2003 5:24 PM
Subject: Re: sketchy laugh test: device discovery BOF


> If you read IEEE 802.1ab closely, it is not really a general "device
> discovery" protocol.  It is more along the lines of Cisco CDP -- a
protocol
> useful for discovering L2 topology and learning some things about device
> configuration on the link.
>
> One reason why I say that IEEE 802.1ab isn't really a general "device
> discovery" solution is that unlike the 802.11 discovery, there is only
> support for Beaconing, and no Probe Request/Response mechanism.  That
means
> that 802.1ab is not really suitable for use on wireless links, or even
wired
> links with multiple potential networks (such as an Ethernet replacement
for
> PPPOE, say).  Among other things, not having  Probe Request/Response
> mechanism means that a host has to wait for the Beacon (every 200 ms with
> LLDP) which can be too time consuming.
>
> In addition, the LLDP attribute list is somewhat limited in that it only
> supports 255 attributes and there is not very good support for extending
it.
>
> I'm told that IEEE 802 is contemplating creating a separate "device
> discovery" solution to handle some of these other scenarios.  Such a
> protocol, if implemented would be likely to be used by multiple groups
(e.g.
> IEEE 802.16, 802.20, etc.) and therefore needs a fair amount of
> extensibility.
>
> Glancing over the DDP design, it shares some of the limitations of LLDP in
> that it has no Request/Response mechanism. Running over IP is problematic
in
> that regard because the querier may not have an IP address yet.  DDP is
more
> general in that it supports ASN.1 encoding and so might be quite amenable
to
> addition of functionality from different groups. However, most of the
> generality is needed in wider usage scenarios than is contemplated in LLDP
> or DDP, so I'm not clear that there are real benefits to this.
>
> _________________________________________________________________
> MSN 8 helps eliminate e-mail viruses. Get 2 months FREE*.
> http://join.msn.com/?page=features/virus
>
>
>