VoIP Mailing List Archives

[grae at digilord.net]

Hello all,
I know this is done and I think I figured out how to do it but I don't
want to reinvent the wheel so here goes. I am looking for a program
that will sit on the PBX. This program will intercept DHCP reply
packets destined for phones, inject "option 66" into the packet and
release it back onto the network.

Some of you might be wondering why I want a program like this. Simple.
Lazy clients. They don't want to mess with their network infrastructure
to assist us with automated deployment of SIP devices. They also don't
want 50-100 devices connecting to an off site server downloading 20-40MB
of firmware on a reboot.

The PBX is not hard coded with an IP address. It's DHCP. They were
willing to allow the PBX on the network and assign it a static DHCP
address.

Is what I am looking for not possible? Does someone have a sensible
solution that doesn't involve dropping the client (yes someone suggested
that)?

Thanks in advance for any help you can give.

DigiLord

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[rupa at rupa.com]

On Wed, Sep 23, 2009 at 10:19 AM, digilord <grae@digilord.net> wrote:

[brian at freeswitch.org]

What you want is NOT possible the way you describe it. Snom does a
multicast PNP which lets you reply with a notify. Polycom does a
DHCPINFORM which lets you respond with a DHCPACK with additional
options. Aastra does MDNS which dictates where to go get the configs.

/b

On Sep 23, 2009, at 10:19 AM, digilord wrote:

[dave at 3c.co.uk]

I don't think it's trivially possible, unless you can stick the PBX
between the DHCP server and the rest of the network. The reason is that
DHCP reply packets are not broadcast, but sent back to the MAC address
of the originator, so your Ethernet switch won't even let your PBX see
the replies.

Even if it could see them, add something to them and retransmit, the
client will almost certainly already have seen the original reply and
would be likely just to ignore the later one.

Any reason why you can't just ask them to add that option to their
existing DHCP server?

And how do you know it's done, and, if you've figured out how to do it,
could you share?

--Dave

[grae at digilord.net]

Brian,
Is there code someplace that I can get that will help with the Polycom
DHCPINFORM way?

Thanks

On Wed, 2009-09-23 at 10:46 -0500, Brian West wrote:

[grae at digilord.net]

I thought I had it figured out and was just missing one piece. Brian
provided me with the missing info. My assumptions were wrong. Now I
need to find software that will do what he described.

On Wed, 2009-09-23 at 18:51 +0300, David Knell wrote:

[oseslija at gmail.com]

Polycom responds to SIP server dhcp option (I think it's 120). I haven't still seen any other phone doing that.

Ognjen

On Wed, Sep 23, 2009 at 6:16 PM, digilord <grae@digilord.net (grae@digilord.net)> wrote:

[brian at freeswitch.org]

I have perl code for both snom-pnp and polycom dhcp inform but my wish
list looks attractive

/b

On Sep 23, 2009, at 12:09 PM, Dan White wrote:

[dwhite at olp.net]

There are several ways to accomplish this, with enough effort.

The most straight forward approach is to run two DHCP servers on that
network, with each of the DHCP servers ignoring the OUIs of devices they do
not wish to manage.

You'll need to configure two separate pools on the two
servers (and turn off the authoritative option in ISC DHCP). But those
pools could be in the same subnet if needed.

Another approach might be to run a custom DHCP relay on the PBX which
injects the appropriate option into the response; again, with the primary
DHCP ignoring requests from your phones based on a class statement (e.g.).
I've done something similar in an ISP environment before. I can send you
my rather ugly PERL code if you'd like.

On 23/09/09 08:19 -0700, digilord wrote:

[brian at freeswitch.org]

its in the FAQ first question

/b

On Sep 23, 2009, at 1:41 PM, Mitul Limbani wrote:

[mitul at enterux.com]

Hey Brian,

On 23-Sep-2009, at 11:16 PM, Brian West <brian@freeswitch.org> wrote: