[lug] Business VOIP Advice...

[Nate Duehr]

On Sep 2, 2009, at 2:19 PM, Zan Lynx wrote:

> Sean Reifschneider wrote:
>> On 09/02/2009 08:52 AM, Ryan Kirkpatrick wrote:
>>> telco refuses (for their own VOIP service) to put QoS on their end  
>>> of the
>>> T1/DSL/Cable? For more details, read on...
>>
>> The reason to go for a provider that offers both the line and the  
>> VoIP
>> service is that they will do the right thing for the QoS to make  
>> sure that
>> data traffic doesn't swamp the voice.
>>
>> Otherwise, you might as well just get a data line and whatever VoIP
>> provider you like on the Internet and deal with these issues.
>>
>> Now, remember, a T1 is *NOT* a high speed Internet service.  I'm so  
>> old
>> that I remember when a T1 was a high speed connection.
>
> Absolutely a T1 is a high speed Internet link. If you cannot handle
> about 20 simultaneous VOIP calls on a T1 then you are using the wrong
> software.

I don't think that's what Sean was saying.  Most businesses beyond a  
mid-size are installing DS-3's or faster these days.  The fiber being  
accessible is the key, but if it is... it doesn't take marginally that  
much more money to hang a DS-3 into a building than it does to hang  
multiple copper T1's.

He's saying, relatively these days... a T1 is bloody slow.

Can it handle plenty of voice calls when done right?  Absolutely.  If  
you just mix all your user's data traffic and the voice traffic with  
no segregation, will the voice suffer on a T1 if even a single person  
starts a large download from a site that'll feed at something faster  
than 1.544 Mb/s?  Absolutely.

(Ironically this is the same debate that's driving the business units  
at large telcos to crazy extremes like making the Internet NOT be Net  
Neutral.  If 5% of users eat up 90% of bandwith (ficticious numbers,  
but often real on individual links) with BitTorrent traffic, and no  
voice, HTTP, or other TCP services can cram their way through, the so- 
called "evil" bandwidth owners want the right to throttle the protocol  
that's hogging the pipe they have in place.  The fact that they  
advertised (foolishly) "unlimited" service, was always a fallacy...  
but people now expect that level of service.  And there are other  
issues, too... just a side-trip down telco lane.  One can also argue  
that a telco refusing to light up all colors on a DWDM fiber mux to  
artificially create "scarcity" to keep prices higher, is probably  
"evil" too, but it's much more hidden from view than issues like  
dropping BitTorrent client traffic arbitrarily are.)


> One single dedicated voice channel is 64 Kbps. A T1 is 1.5 Mbps and
> could handle 23 lines when connected to a PBX in the olden days.

Various available CODECs can do far better than 64 Kb/s for a voice  
channel, sometimes at a loss of audio quality.  The main thing keeping  
it from happening is that even though there are standards, not all  
vendors implement them in a consistent way... a common problem of  
Internet IETF type standards, even though most CODECs are ITU  
standards... G.711 is still the "lingua franca" of telco, but G.729  
and friends could really help with bandwidth utilization... if they  
could be consistently and properly used.

> If you cannot do the same while using a packetized protocol that  
> doesn't
> even have to transmit much of the time, then something is very  
> wrong, as
> I said.

Actually TCP log-jams are a well documented phenomenon when a link is  
saturated.  It's not like the concept is new that if you push the  
various layers to their max traffic levels, their ability to pass that  
traffic diminishes with almost exponential results... because that's  
EXACTLY the math that was in the standards to start with.  Take an OLD  
example... half-duplex 100 Mb/s Ethernet falls completely apart at 85  
Mb/s, this is a well-known fact.  TCP has had tons of things "grafted  
on" to it to handle timing issues over the decades.  UDP is ... well,  
Unreliable... as expected, and loses out to other traffic... as it  
SHOULD, but it's also the preferred way to transport audio (seems back- 
assward, doesn't it) for telco systems... then we layer on QoS, VLANs,  
etc... to try to make up for the fact that we're using the most  
unreliable protocol available to us in the IP "stack" to pass the  
traffic in most dire need of "real-time" delivery.  (And people in IT  
wonder why others think we're idiots... in many ways, we ARE!)

> Or I suppose you could be trying to do CD quality voice. That's a  
> waste
> of time.

No one was expecting that.  I think Sean was just saying "Bandwidth is  
a LOT cheaper than when I started, and it doesn't make sense to ONLY  
buy a T1 in many cases, nowadays."  I hope I'm not putting words in  
his mouth, but I "got" right where he was coming from.  He and I both  
probably EASILY remember when a T1 was well over $1000/month.  Now you  
can get multiple fiber DS-3's delivered to buildings, not  
datacenters... for that.

And it'll keep getting cheaper.  Even my measly "residential" Comcast  
drop (yes, I have a commercial account but that's only for static  
IP's... I still share the pipe with the neighbors) can do 12 Mb/s to  
my house in it's sleep.  A T1 @ 1.544 Mb/s would put me to sleep  
waiting for a web page to load...

"He who dies with the most bandwidth, wins!" -- LOL!

--
Nate Duehr
nate at natetech.com

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