Re: [hylafax-users] Using a serial modem through a converter from ethernet to serial

["Rob Rothberg" <rrothberg@xxxxxxxxx>]

FWIW, we tried the VM route initially here.  I started small with a VM on an Intel Core 2 Duo system with a gig of memory.  This system did nothing but run the VM.
On the VM I installed Asterisk, HylaFAX and integrated the two with IAXmodems (actually I should say Lee Howard did this for me).  First I tried faxing over VoIP.  Broadvoice failed 100% of the time.
I then tried Vitelity, that worked occasioanlly.  Clearly VoIP was not the answer, so II interfaced Asterisk to 4 PSTN lines with an SPA-400.  This failed because of volume level issues most likely as a result of the SPA-400.

Next I installed Hylafax on a dedicated box and purchased a Mainpine Rockforce Quattro+ and this worked very successfully, but it wasn't enough to meet my needs.

I then had a T-1 installed with 11 PRI channels and purchased a RedFone FoneBridge2.  I still had Asterisk running in a VM working as our production PBX at this point, so I interfaced the VM Asterisk install
with the FoneBridge.  Initially the two pieces of hardware had a Cisco layer 2 switch between them and timings between the two pieces of hardware weren't good enough for 100% reliability.  I then plugged them into
a dedicated switch, some improvement but still not good enough.  RedFone told me I needed a dedicated NIC on the server and to plug the FoneBridge into it directly.  The VM was just introducing too much
latency.  I finally just installed Asterisk on the dedicated Hylafax server with two NICs, and plugged in the FoneBridge2 directly.  Lee set up 11 IAXmodems interfaced to Asterisk.  No more issues.  We've been sending around 500 pages a day reliably with this config (reliably in the sense all the telecomm stuff is working great, there are other unrelated issues but they're being worked out).

The lesson I learned here was that while it might be POSSIBLE to get a VM working reliably (probably not the free version, you'd probably need to play with the $$$ version and tweak performance parameters and memory allocation), it's not worth the time and effort, and I don't know how long it would take before I trusted it for faxing.  It was fine for voice but faxing is a different story.

On 2/3/07, andrew rinaldi <andrew.rinaldi@xxxxxxxxxxxx> wrote:

Hi Mark,

'Speed' is not the issue here... With Ethernet it's what happens when you
get large packet loss (which equates to lost 'audio' in our case)... And
with virtualisation it's the loss of deterministic behaviour (which degrades
low level timing)... In both cases some systems will work and some won't...
And the 'working' systems can almost always be broken by heavy work load on
the network or system.

A good example of what happens with Ethernet packet loss is to run a VoIP
call across a busy network and listen to the call quality degrade.... In fax
this quickly equates to a failed call.

Have you ever stress tested your setup ?  How many fax's do you send/receive
in a typical day ?  In our lab we've been able to break most (maybe all)
virtual servers that we have tested for use with fax servers.

Ultimately, I'm trying to encourage people to keep it simple because in my
experience that always works out for the best.

Regards

ANDREW RINALDI
Mainpine Limited Support
USA +1 503 822 9944 | Asia/Europe +44 1225 869439
andrew.rinaldi@xxxxxxxxxxxx | www.mainpine.com

-----Original Message-----
From: hylafax-users-bounce@xxxxxxxxxxx
[mailto:hylafax-users-bounce@xxxxxxxxxxx ] On Behalf Of Mark
Sent: 03 February 2007 16:44
To: hylafax-users@xxxxxxxxxxx
Subject: Re: [hylafax-users] Using a serial modem through a converter from
ethernet to serial

andrew rinaldi <andrew.rinaldi <at> mainpine.com> writes:

>
> Hi Davide,

< snip >
< snip >

> > Hi Davide,
> >
> > I suspect that this will never work reliably.... Firstly, running
HylaFAX on
> > a virtual server removes the tight timing and control needed between the
> > protocol engine and the fax hardware, and secondly, the Ethernet to
serial
> > converter does the same thing but with even less control of the timing.

Andrew,

Do you not believe that the use of good quality network-serial adapters, and
virtual servers - if they are VERY FAST, would work reliably?  I believe
that
many virtual servers out there are over-powered and under-utilized.  At
least in
my case I have been experimenting with VMware Server (free version) on my
personal Acer Aspire 3000LMi laptop, and am using with it an ESP-2MI serial
adapter with a good serial modem - it receives and sends faxes just fine.

Mark




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