Reaction of Equipment after Change of IP-Number?

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I'm using VoIP behind a NAT Modem-Router from Netgear and a Sipura
SPA3000 for inbound and outbound telephony from all my phones.

But I get a new IP-number at least once a day from my DSL Provider.
After this number change the Sipura failes to reregister correctly.

Does anybody have problems with these IP-number changes?
How do you solve this?

Wolfgang

Re: Reaction of Equipment after Change of IP-Number?


Wolfgang Barth wrote:
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Your configuration should look like this:
Modem<==>SPA3000<==>Router<==>pc(s)

and all four devices should use DHCP to get IP and DNS addresses.

Re: Reaction of Equipment after Change of IP-Number?


Rick Merrill wrote:
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But I have a modem-router with DHCP and behind that there is the SPA3000
and the PCs. I cannot change this configuration.
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PCs and Sipura do use DHCP to get local IP and DNS addresses.
The modem-router gets its via PPPoE.

Wolfgang

Re: Reaction of Equipment after Change of IP-Number?


Wolfgang Barth wrote:
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Why not?  How do  you expect the SPA3000 to do QoS?

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Why is that?


Re: Reaction of Equipment after Change of IP-Number?


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For example, because the router handles the PPPoE decoding and NATting.

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Because that's how things work when your provider uses PPPoE and gives
you only one IP address (assigned through PPPoE), which obviously can't
be shared among devices: hence the need for NAT functionality, and
often the DHCP service to assign the local IP addresses, both of which
can be provided by the route.

That said, I have the same configuration as Wolfgang's (SPA-3000 behind
the NAT router) and never noticed that problem. On the other hand, I
used to have a different type of problem with a Netgear MR814v2
(http://voxilla.com/index.php?name=PNphpBB2&file=viewtopic&p=13986#13986
). Now I'm running Linux on a Linksys WRT54G (http://openwrt.org ) and
Netgear is only a painful memory :-)

The nice thing of using Linux as router is that one can run tcpdump to
capture packets to a file, transfer the file to a bigger machine and
inspect them with Ethereal. This would tell you more about why the
re-registration fails: which is a quite unusual thing. Wolfgang, are
you sure it fails? Or perhaps is it not repeated often enough, so that
after the change of IP address the remote SIP registrar still remembers
the old address? In that case, you could try to reduce the
re-registration interval of the SPA-3000 to, say, a couple of minutes.
You can do this putting 60 (the number of seconds) in the "Register
Expires:" field of the "Line 1" and "PSTN Line" screens of the Admin
interface.

Another way of inspecting the SIP packets would be installing a NON
switching 10baseT hub between router and SPA-3000, and use it just like
a T-joint to tap into the traffic with a monitoring machine directly
running Ethereal. Unfortunately, in these days non-switching hubs are
hard to find.

Enzo


Re: Reaction of Equipment after Change of IP-Number?


Enzo Michelangeli wrote:
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Register expires is 3600 seconds in the moment. But reregistering failed
several times after IP-change. At least for 10 hours. But I will give it
a try an reregister earlier.
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In this moment I have this combined modem-router, so I do not want to
change hardware.

Thanks for the hints.

Wolfgang

Re: Reaction of Equipment after Change of IP-Number?




[snip]

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I've got a 16 port 10-base-T hub if anyone wants it..! Redundant since I
upgraded all my stuff to 100-base-T.

Ivor




Re: Reaction of Equipment after Change of IP-Number?


Wolfgang Barth wrote:
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By the way, which NAT-related options have you set under "NAT Support
Parameters" in the SIP screen of the Admin interface? I have set
everything to "yes" with the exception of "Send Resp To Src Port:"
which is a "no"; "STUN Server:" points to "stun.fwdnet.net:3478"; "EXT
RTP Port Min:" and "EXT IP:" are both blank, and "NAT Keep Alive
Intvl:" is set to "15".

Enzo


Re: Reaction of Equipment after Change of IP-Number?


Enzo Michelangeli wrote:
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Ok. I'll think about this. But as far as I understood its necessary to
set "Send Resp to src port" to yes because my router users "port
restricted cone NAT".

But its working ok since two days now. No idea why.

Wolfgang

Re: Reaction of Equipment after Change of IP-Number?


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Fortunately my IP address only changes every two or three weeks. But my
Sipura 1001 has the same problem.

If I go to any of the admin pages on its web interface and click the button
to save changes (even though I haven't made any changes) it immediately
re-registers properly.

I imagine that after some timeout interval it might straighten itself out as
well but I've never been patient enough to wait and see.

miguel
--
Hit The Road! Photos from 36 countries on 5 continents: http://travel.u.nu
Latest photos: Queens Day in Amsterdam; the Grand Canyon; Amman, Jordan


Re: Reaction of Equipment after Change of IP-Number?


Miguel Cruz wrote:
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You are using DHCP on the router and using private IP addresses on all the
connected devices, aren't you..?

Ivor



Re: Reaction of Equipment after Change of IP-Number?


Ivor Jones wrote:
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Yes. I do use a modem-router from Netgear with port restricted cone NAT.

This is my DHCP source for my private LAN, where the SIPURA is in.

Everything works properly. Even NAT traversal.
The only problem is that reregistering(?) and/or NAT stay alive(?) tend
to fail after change of the EXTERNAL IP-Number.

Wolfgang




Re: Reaction of Equipment after Change of IP-Number?


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Yes, the problem is that the Sipura device doesn't have any way of being
actively alerted that the external IP of the router has changed, so it
constructs its SIP headers incorrectly.

I suppose it could be configured to check more frequently (with the STUN
server or something); I haven't been sufficiently motivated to look into it
further yet though.

miguel
--
Hit The Road! Photos from 36 countries on 5 continents: http://travel.u.nu
Latest photos: Queens Day in Amsterdam; the Grand Canyon; Amman, Jordan

Re: Reaction of Equipment after Change of IP-Number?


Miguel Cruz wrote:

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It doesn't *need* to know. All the Sipura needs to know is the private IP
address of the router, usually 192.168.1.1 or something similar. It
doesn't know or care about the public IP address, only the router does.

My connection has what I call a semi-static IP address, in that it can
stay the same for weeks on end then change for no apparent reason..! My
Sipura has never failed to register because of it.

Ivor



Re: Reaction of Equipment after Change of IP-Number?


Ivor Jones wrote:
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Actually it _should_ care, in order to meet the SIP specifications; but
some registrar proxies flat-out ignore the SIP headers and use, as IP
address and UDP port, the same present as source on the headers of the
packet that contained the registration request. This violation of the
SIP specs often saves the day, but sometimes the results turn out to be
annoying because it prevents third-party registration. Before
understanding what was going on, I wasted days trying to register a
Sipura SPA-3000 on multiple registrars using a utility, Sipsak
(www.sipsak.org) running on a PC on the same LAN. I did that because
the SPA-3000, due to a silly firmware limitation, can place calls
through several outbound proxies BUT can register only on one of them.
Well, it didn't work, despite the fact that I passed all the right
parameters to Sipsak and Sipsak prepared the SIP headers accordingly:
the registrar always registered the SPA-3000 at the UDP port mapped as
source by the NAT router for the packets coming from the Sipsak client,
which of course was different from the one I had specified for the
SPA-3000 :-(

Moral of this story: if you deal with NATs, whenever possible avoid SIP
like the plague, and use IAX2.

Enzo



Re: Reaction of Equipment after Change of IP-Number?


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I think we can take it for granted that if the thing is doing anything at
all, it knows its proximal router's address.

But if you sniff SIP traffic you will probably see your external (outside of
NAT) IP address communicated in the payload (not just in packet headers). At
least I do between my Sipura (inside NAT) and Asterisk server (in the wild).

miguel
--
Hit The Road! Photos from 36 countries on 5 continents: http://travel.u.nu
Latest photos: Queens Day in Amsterdam; the Grand Canyon; Amman, Jordan

Re: Reaction of Equipment after Change of IP-Number?


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If it's DHCP then it should come with a lease time.  Does the sipura ignore
the lease time?


Re: Reaction of Equipment after Change of IP-Number?


wkearney99 wrote:
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Seams so.

Wolfgang

Re: Reaction of Equipment after Change of IP-Number?


Wolfgang Barth wrote:
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I thought you said the sipura was given a fixed IP...

Re: Reaction of Equipment after Change of IP-Number?


Rick Merrill wrote:

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Internally it uses DHCP but based on the MAC it will always be the same.

But the problem is with the EXTERNAL IP-number which is very different
each day.

Wolfgang

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