Subject: Digital Radio Configuration Question

From: "Richard C. Ascheri" <[email-masked]>
Date: Mon, 17 Apr 2000 13:35:43 -0700

Hello,

I'm a Systems Engineer at Raytheon Company.  I have been working on the 
development of a digital IP based radio for some time now.  The radio has 
an Ethernet interface, PPP interface, and an ADDSI X.25 interface.

My question relates to the configuration of the radio.  To configure the 
radio we have an implementation of SNMPv2.  This implementation allows the 
radio to be configured over the Ethernet or PPP interfaces using the SNMPv2 
protocol.

My question relates to configuring the radio without knowing it's IP 
address.  I understand that SNMP requires the IP address of the device you 
want to configure.

I am interested in a standard method of announcing the IP address of the 
Ethernet interface.  This would allow a configuration tool to look for the 
announcements and then send SNMP configuration messages to modify the 
radios configuration.  For this scenario you can assume that the radio will 
be attached to a single host over an Ethernet interface.  There will be no 
other hosts or radios on the network.  Assume that the IP address of the 
radio is NOT known.  It could be set to anything, even an address outside 
of the range of the hosts subnet.

I have looked at a number of RFC's but have found these two that may work:

RFC 1256 - ICMP Router Discovery.  This rfc does announce the IP address, 
however, for this scenario I'm not interested in saying that this radio is 
the next hop gateway.  Given that the radio has numerous interfaces and an 
TCP/IP stack you might consider this a router.  However, I don't really 
feel that this RFC directly relates to solving the configuration problem. 
 The host is not really looking for it's next hop gateway.  It's looking 
for devices that can be configured through SNMP.

RFC 2608 - Service Location Protocol v2.  This rfc does imply that I could 
create a "Configuration-Service" and announce its availability using the 
SNMP protocol.  This actually sounds like the right kind of solution to my 
problem.

But now I'm wondering whether or not there is something else that I haven't 
found.  Maybe something in the works, as a draft, or a working group that 
is responsible for looking at these kinds of problems.

Any and all comments would be gratefully appreciated.

Thanks in advance.
Rick.

Richard C. Ascheri					Raytheon Company
Principle Systems Engineer				1801 Hughes Drive
Network Technology Group				Fullerton, CA.  92836
C3I Systems					http://www.raytheon.com
[email-masked]

---

From: "Richard C. Ascheri" <[email-masked]>
Date: Fri, 21 Apr 2000 10:41:07 -0700

I'm trying to announce to the host connected to the Ethernet interface. 
 Yes the digital radio does have other interfaces, but I believe that only 
one type of interface (ethernet or PPP) will be active at any one time, 
i.e. we won't have the PPP interface working at the same time as the 
Ethernet.  At least that is not the plan so far.

To bring you up to date:  I started down the path of using the Limited 
Broadcast address and an ICMP Echo Request message to get the Digital Radio 
to announce it's IP address.

I wrote a simple program that sends an ICMP Echo Request message to the 
limited broadcast address of 255.255.255.255.  This appeared to work when 
testing it with many of the hosts on our network, i.e. numerous hosts 
responded with their own IP address...  However, the digital radio does NOT 
respond because the VxWorks operating system apparently doesn't support 
answering the limited broadcast address...(The documentation suggests that 
you have to set the broadcast address for the interface, and 
255.255.255.255 is illegal).  So that method looks like a dead end.  That 
was going to be the easiest and the cleanest.

The next method I plan to try is to use a Multicast address to exchange 
maybe an ICMP Echo Request message (or some other message) with one 
another.  First idea is to identify a Multicast address to use to do this. 
 I want to try and use one of the predefined multicast addresses.  Any 
suggestions from anyone as to which one might be appropriate for this kind 
of thing?

If the above methods fail then my final attempt will be to implement a 
minimum Service Location Protocol V2 Implementation in the digital radio, 
and have it announce some kind of configuration service.  The host could 
then look for this configuration service and get the information it needs 
from the SLP messages.  The thing I like about this method is that it is a 
standard RFC, and I can later expand on the other services that I might 
want the digital radio to announce.

Any other suggestions would be greatly appreciated.

Thanks in advance,
Rick.

-----Original Message-----
From:	Michael B. Bellopede [SMTP:[email-masked]]
Sent:	Friday, April 21, 2000 7:20 AM
To:	Richard C. Ascheri
Subject:	RE: Digital Radio Configuration Question

If you have more than one physical interface, each with its own IP, than
this device definitely is considered a router.  Are you trying to announce
the IP of the ethernet interface to the connected ethernet host (via
ethernet interface), or announce to a host communicating with the radio
interface?

-Michael B. Bellopede
 [email-masked]
 "There is no spoon."

-----Original Message-----
From: Richard C. Ascheri [mailto:[email-masked]]
Sent: Monday, April 17, 2000 1:32 PM
To: [email-masked]'
Subject: Digital Radio Configuration Question

Hello,

Thanks in advance.
Rick.

Network Technology Group                                Fullerton, CA.
92836

---

From: "Richard C. Ascheri" <[email-masked]>
Date: Fri, 21 Apr 2000 12:50:27 -0700

John,

I called it the "Limited Broadcast Address" because that is what Richard 
Stevens calls it in his book, "TCP/IP Illustrated Volume 1", which I had 
thought was considered the BIBLE amongst networking professionals.

Secondly, I am aware that no router in the world forwards this address.  It 
says so in the book, and it would be rediculous to do so in the first 
place.

My problem relates to obtaining the IP address of a digital radio which is 
connected to the same physical network as the host, but which you do not 
know it's IP address.  You have no other means of finding out its IP 
address, i.e. no look inside the box.  It does support SNMP, however you 
need an IP address to read its configuration.  Hence, the thought about 
using the limited broadcast address and an ICMP Echo Request message.

As for VxWorks being cautious, no I think it is more of an oversight on 
their part.  I'll have to ask them why....

Thanks,
Rick.

-----Original Message-----
From:	John Stracke [SMTP:[email-masked]]
Sent:	Friday, April 21, 2000 11:36 AM
To:	[email-masked]
Subject:	Re: Digital Radio Configuration Question

"Richard C. Ascheri" wrote:

> limited broadcast address of 255.255.255.255.

That's not the limited broadcast address; that's the universal broadcast
address, the one that would send a packet to every host in the Internet.  I
say "would" because it's such an obviously bad idea that essentially every
router in the world comes out of the box refusing to forward it.  Most host
software will respond to it, though; VxWorks is probably being cautious.

--
/==============================================================\
|John Stracke    | http://www.ecal.com |My opinions are my own.|
|Chief Scientist |=============================================|
|eCal Corp.      |Do not suspect that I am not human.          |
[email-masked]|                                             |
\==============================================================/