[Equipment] SPA2102 with PPPOE

[Equipment] SPA2102 with PPPOE
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slcotten @ 4th Nov 09:39AM:
[Equipment] SPA2102 with PPPOE

Hi,

This is a networking question, not really a SIP or VOIP question other than the device I'm using. If there's a better place to post this please let me know.

I've got an SPA2102, and DSL and I'm using it in this way:

Modem (in bridge mode) --> SPA2102 (with PPPOE) --> Wireless Router in SPA DMZ

Everything works (SPA2102 connects, gets IP from ISP). However, over time, I notice that latency between the SPA and the ISP gateway goes up. Over the course of a couple of days ping reply times go up from 20ms to 2000ms (yes 2 seconds). Cycling the power on the SPA (power down, wait a few seconds, power on) resets the latency back down to 20ms again.

Has anyone seen this? Any ideas? Is there any way to set MTU and connection timer settings on the SPA?

Thanks,
Lloyd
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Stewart @ 4th Nov 12:50PM:
Re: [Equipment] SPA2102 with PPPOE

There is no auto-disconnect option, but IMO you should try to fix the problem rather than cover it up. Unfortunately, AFAIK there is no MTU setting. It does automatically go to 1492 when using PPPoE, but may be a problem if you need to do PPP on the modem.

Running latest SPA firmware (5.2.10)? If not, try upgrading.

Does the high latency affect the phone? You can test by calling 909-390-0003. You won't hear a ring -- just start talking and your voice will be echoed back. About 100 milliseconds of what you hear is in the test line.

Do you have a way to capture traffic to see what is going wrong (dumb hub, managed switch, or PC with two wired NICs)?

What model modem? Router? Third-party firmware in router? Line sync speeds up/down?

What QoS settings in SPA?

Any significant background traffic, e.g. P2P file sharing?
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slcotten @ 4th Nov 02:54PM:
Re: [Equipment] SPA2102 with PPPOE

Hi thanks for the reply, I know these things are always difficult to help out with just by descriptions. I will give some of things you suggest a shot later, but for now here are some answers to the things I know:

said by Stewart :

Running latest SPA firmware (5.2.10)? If not, try upgrading.

Yes, running latest firmware (that version).

said by Stewart :

What model modem? Router? Third-party firmware in router?

Speedstream 4200 modem with ISP moded firmware (did some research on this already and they've disabled access to a bunch of stuff).

D-Link DIR-615 Router with factory firmware (is also latest available from d-link).

I will mention that at the same time I was getting latency to the gateway I would ping the router: < 1ms and the SPA < 2ms (both the LAN and WAN side).

said by Stewart :

Line sync speeds up/down?

Generally speaking get 800-900 Kbps down, 350 Kbps up.

said by Stewart :

What QoS settings in SPA?

QOS Policy: On when phone is in use
QOS QDisc: TBF
Maximum Uplink Speed: 256 Kbps

said by Stewart :

Any significant background traffic, e.g. P2P file sharing?

No other traffic at all.
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CajunWon @ 5th Nov 01:27PM:
Re: [Equipment] SPA2102 with PPPOE

fwiw: There is a newer version, I've been using since June:

Product Name: SPA-2102 Software Version: 5.2.5 Hardware Version: 1.2.5(a)

I was told this version offers benefits when in router mode, though I do not know specifics. I had the SPA placed behind cable modem at the time due to router induced latency.
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slcotten @ 6th Nov 08:09AM:
Re: [Equipment] SPA2102 with PPPOE

said by CajunWon :

Product Name: SPA-2102 Software Version: 5.2.5 Hardware Version: 1.2.5(a)

That's the version that came on this SPA when I bought it and I thought 5.2.10 was a later version than 5.2.5 so I upgraded. Is it not?
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Stewart @ 6th Nov 12:03PM:
Re: [Equipment] SPA2102 with PPPOE

said by slcotten :

That's the version that came on this SPA when I bought it and I thought 5.2.10 was a later version than 5.2.5 so I upgraded. Is it not?

You are correct, 5.2.10 is newer; see »www.cisco.com/en/US/docs/voice_i···2-10.pdf .

Sorry that I've been unable to provide further useful input, since I don't know whether your modem can be set up in a way that works around the present problem. Did you find out whether the trouble affects the phone? Or any details as to what is going wrong?

If your modem can do PPP with 1:1 NAT (provides single private IP to attached device), you could set up the SPA as DHCP client. Depending on your VoIP provider, you may need to set up NAT mapping in the SPA (for it to function or to get best latency). Your PC apps will see triple NAT, but they see double NAT now, so that's unlikely to be a problem. You may need to force NAT mode on the SPA.

If the modem can do PPP and give a public address to the attached device, you might give it a try, but IMO that mode is buggy in most modems.

If the modem can do PPP with real NAT, you should be able to put the SPA in bridge mode. You'll need to set up port forwarding or DMZ in the modem for any PC apps that need it and, depending on your provider, for the SPA as well.

In any of the above modes, MTU should not be a problem, because the SPA itself should not generate any huge packets, and you can set MTU on the router for the other traffic.

If the above is not applicable or does not help, IMO you'll either need to determine the details of what is happening, or test with another modem and/or router to see where the incompatibility lies.

Edit: If behind a modem offering only a single private IP address (1:1 NAT), the SPA needs to be in NAT mode.
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slcotten @ 6th Nov 03:06PM:
Re: [Equipment] SPA2102 with PPPOE

Yeah, I've been waiting for the problem to occur again and it hasn't yet, so I've not been able to try out some of your suggestions. :huh: I did try that echo test number, but I would have to modify my dial plan for it to work and doing that would reset the SPA which I didn't want to do right now (to test what seemed to be a problem that occurred over a period of uptime.)

Yes the modem can do PPP and that's the way the ISP had me set it up originally, but it also blocks quite a few ports (not sure if it's NAT, or some other type of firewall), but I was hoping to setup some remote admin features on my network, and couldn't do it because of the modem. The ISP has pretty well crippled the modem.

Thanks for the help. I will keep monitoring things and report back any details when I come on them.
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Stewart @ 6th Nov 03:30PM:
Re: [Equipment] SPA2102 with PPPOE

If it's just for remote admin and you have a PC or server always on, specific blocked ports shouldn't be a problem. Connect from outside to the PC, e.g. by VNC or Remote Desktop, and do your admin from there. If TCP ports 5900 (VNC) or 3389 (RDP) are blocked, just set your server to use different ones. That is probably a good idea anyway, as it provides some security against worms scanning for server vulnerabilities.

I don't understand your comment about the dial plan. Don't you have some string of digits that will connect you to a US number?
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slcotten @ 7th Nov 08:12PM:
Re: [Equipment] SPA2102 with PPPOE

Thanks for the ideas, however, I've pretty well tried every common port that I could think of (like 5900, 80, 8080, 8081, 21), and odd ball ones, and it doesn't seem to let anything through (without something initializing it on my end (I guess this is NAT?). I suppose this is a good thing for since the ISP tells me that they "officially" support connecting a computer directly to the modem. Using it in bridge mode seem to be the only way to do more stuff with it.

Sorry didn't catch on that it was a US number that I had to dial 1 before. And yes it works now.

Anyway, it happened again today, and a few more details and tests:

Ping times to the gateway varied between 20ms and 2000ms+ but seem to spend most of its time around the 500-900ms mark.

Did a couple of VisualWare tests, QOS was around 36%. Jitter was 3.9ms, normally this is 1ms.

Tried that echo test number and basically it was pretty much broken that I couldn't even estimate the latency. I tried again later (when everything was operating normally) and it's about 300ms I would guess. Latency with the echo test provided my normal provider (CallWithUs) is noticeably less.

Anyhow, I'm beginning to doubt my diagnoses as to SPA PPPoE being the problem in the first place. When I tried a reboot today on the SPA, it didn't make any difference. So I tried cycling the power (wait 15sec), and still no difference. It wasn't until I cycled the power on the modem (Speedstream 4200) that the problem was resolved. So I'm thinking I should go explore the possibility that it's a problem with the modem in that mode.

Now that it's operating normally again, I setup a 7 day SmokePing test here:
[removed since I did a reset and got a new IP... going to try something different]
I'm going to monitor that and see if it will reveal anything about how this problem begins (whether or not it's sudden or gradually increases over time).
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Stewart @ 8th Nov 02:26AM:
Re: [Equipment] SPA2102 with PPPOE

Can you borrow a modem (of different model) to test? Get a different one from your ISP? Buy one at a local store where you can return it if it doesn't help your system?

If you're stuck with the 4200, is a firmware upgrade available? In its NAT mode, is any kind of port forwarding available? (This is sometimes called "virtual server", "special applications", or some other misleading name.) If not, is DMZ available? Any firewall settings that can be turned off?

Does the modem have a command line interface? If so, perhaps some stuff disabled in the Web interface is available in the CLI.
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