[138166] in North American Network Operators' Group
Re: What vexes VoIP users?
daemon@ATHENA.MIT.EDU (Owen DeLong)
Mon Feb 28 17:28:59 2011
From: Owen DeLong <owen@delong.com>
In-Reply-To: <CFB2F889-A44A-4D34-A8AF-206BE026F49B@puck.nether.net>
Date: Mon, 28 Feb 2011 14:24:41 -0800
To: Jared Mauch <jared@puck.nether.net>
Cc: "nanog@nanog.org" <nanog@nanog.org>
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
It's only an issue if you have a single gateway which is serving up =
multiple public addresses.
SIP is not the only traversal that breaks in this environment, but, it =
does choose to break in some
of the most interesting (especially to troubleshoot when you don't know =
that's what is causing
the problem) ways.
This was not the result of "smart nat" or ALG issues.
I will say that I have not seen a lot of environments that have a single =
gateway that maps clients
to a variety of external addresses and that may account for the number =
of colleagues that haven't
seen this issue before.
It is real. It does exist. It is all kinds of fun (not!) to troubleshoot =
the first time you encounter it.
(The SIP gets through the traversal just fine, but, usually one half =
(and not consistently the same
half) of the RTP streams don't.)
Owen
On Feb 28, 2011, at 1:00 PM, Jared Mauch wrote:
> I've found that sip alg on devices is badly broken and must be =
disabled. This is true of ios and various consumer electronics devices. =
Nat traversal for multiple devices is not an issue in any case I have =
seen.=20
>=20
> Turning off "smart nat" usually solves it.=20
>=20
> Jared Mauch
>=20
> On Feb 28, 2011, at 2:34 PM, Bret Palsson <bret@getjive.com> wrote:
>=20
>> Sorry I didn't include this in the last email...
>>=20
>> We have large clients who have phones registered on multiples of =
public IPs from the same location. Works no problem. We do some trickery =
on our side to make that happen, but I thought all VoIP companies would =
do that.
>>=20
>> -Bret
>>=20
>> On Feb 28, 2011, at 12:25 PM, Owen DeLong wrote:
>>=20
>>> Another vexation for VOIP in the SMB environment is that it rarely =
works particularly
>>> well (if at all) in light of a multiple-external-address NAT pool.
>>>=20
>>> You simply have to map all of your VOIP phones in such a way that =
they consistently
>>> get the same external IP every time or shit breaks badly.
>>>=20
>>> Owen
>>>=20
>>> On Feb 28, 2011, at 11:11 AM, Bret Palsson wrote:
>>>=20
>>>> Since our company is a VoIP company, I will chime in to this topic.
>>>>=20
>>>> Let's start off with the definitions so everyone is on the same =
page:
>>>>=20
>>>> vex |veks|
>>>> verb [ trans. ]
>>>> make (someone) feel annoyed, frustrated, or worried, esp. with =
trivial matters : the memory of the conversation still vexed him | [as =
adj. ] ( vexing)the most vexing questions for policymakers.]
>>>>=20
>>>> Alright, now that that's out of the way...
>>>>=20
>>>> I am only referring to small medium business and some enterprise =
(Those are all our customers, we do not do residential)
>>>> - Seemingly complex.
>>>> - Worried about the "What if the internet goes down" scenario.
>>>> - Call quality.
>>>> - Price
>>>> - Location
>>>> - Outages
>>>>=20
>>>> Responses:
>>>> - Seemingly complex... Very true. Most VoIP companies, both hosted =
and on premises are difficult/time consuming to setup and make work they =
way you want it.=20
>>>> - What if the internet goes down. This one is a challenge. POTS =
actually have issues too, but when analog phone service goes down, there =
is no light on the phone indicating that the phones are not working so =
many customers perceive there is a problem. With the FCC mandating all =
POTS move to a VoIP backend (which for long hauls, is mostly already =
true) POTS will experience the same downtime as the internet.=20
>>>> However as we all know, the internet is built to tolerate outages.=20=
>>>> For most people they don't understand how the internet actually =
works.
>>>> - Call quality... If a VoIP company pays for good bandwidth and =
maintains good relationships with peers, the only concern is the =
last-mile(=46rom the CO to location). Now there is much more that plays =
in quality, ie. codec selection, voice buffer, locality to the pbx.
>>>> - Price... Believe it or not people are worried about paying less =
for better service. Who would have thought?
>>>> - Location... Location is super important both in the last mile and =
PBX.
>>>> - Last mile:
>>>> In older locations the copper in the ground is aged, if you =
can't get fiber and your stuck using T1, lines, then hopefully you are =
in a location that keeps the copper in the ground properly maintained. =
If you are in older locations, which one of our offices are, there are =
remedies, you can contact your bandwidth provider and have them do a =
head to head test using a BERD (bit error rate detector) and they can =
find the problem. But that's a whole other topic.
>>>>=20
>>>> -PBX:
>>>> Some people believe that on premise is the best location for =
a PBX, this may or may not be true. I happen to believe that keeping it =
off premise is the way to go. You get up-time, redundancy, locality, and =
mobility. You just plug in your phone and your phone is up and running. =
Move offices.. got bandwidth? Your good to go. No equipment to worry =
about, say a power outage happens, your voicemail still works people =
call in and are in call queues and have no clue you are down. Feels more =
like POTS with an enterprise backend.
>>>>=20
>>>> -Outages: If the internet does fail, most providers offer WAN =
survivability. The customer plugs in phone lines into the router and if =
the internet goes down, they can make emergency calls or calls to the =
world limited by the number of lines the router can accept and are =
plugged in of course. Now in all our experience going on 7 years now, =
90% of the time WAN outages happen, guess what also dies, the POTS! Who =
would have thought that when cables get cut, that the phone lines were =
also part of the cables?
>>>>=20
>>>> There you go, some common worries, with some answers to hopefully =
sooth the vexed VoIP user.
>>>>=20
>>>> Bret Palsson
>>>> Sr. Network & Systems Administrator
>>>> www.getjive.com
>>>>=20
>>>>=20
>>>> On Feb 28, 2011, at 11:37 AM, Valdis.Kletnieks@vt.edu wrote:
>>>>=20
>>>>> On Mon, 28 Feb 2011 13:29:08 EST, Bret Clark said:
>>>>>> On 02/28/2011 01:17 PM, Leigh Porter wrote:
>>>>>>> VoIP at the last mile is just too niche at the moment. It's for =
people on this list, not my mother.
>>>>>=20
>>>>>> Baloney...if that was the case, then all these ILEC's wouldn't be=20=
>>>>>> whining about POT's lines decreasing exponentially year over =
year!
>>>>>=20
>>>>> I do believe that the ILEC's are mostly losing POTS lines to cell =
phones, not
>>>>> to VoIP. I myself have a cell phone but no POTS service at my home =
address. On
>>>>> the other hand, I *am* seeing a metric ton of Vonage and Magic =
Jack ads on TV
>>>>> these days - if VoIP is "too niche", how are those two making any =
money?
>>>>>=20
>>>>=20
>>>=20
>>=20
>>=20
