[Asterisk-Users] My Sangoma Experience - Review

[mattf]

My Sangoma Experience in Asterisk:			2005-04-07

Having pushed my Digium Asterisk systems to their capacity many times and
figuring out the limits of the Digium hardware I decided it was time to test
an Asterisk-compatible Sangoma Quad T1/E1 card(AFT-A104u) to see if they
live up to their hype of being more efficient than the Digium
variety(T405P). I had talked with someone from Sangoma before at Astricon,
but it was rather informal, he didn't have any literature and I was rather
swamped at the time as it was. Then I saw a posting on the asterisk-users
list about the claims that the Sangoma card does echo-cancelation better as
well as using far less interrupts than Digium hardware(a big bottleneck with
busy Digium systems).

I emailed Sangoma(they are located in Canada) for a quote and quickly
received a phone call from them. They were very interested in getting my
feedback on using their quad port T1/E1 card with Asterisk and they quoted
me a discounted price of $1190 US for the card(They said retail was $1700 US
[Digium quad-cards are $1495 retail but you can get them through resellers
for a couple hundred less]). The Sangoma card comes with a 30-day money back
guarantee and a 3 year warranty.

When I received the card I noticed a couple things right away, it was a very
professionally packaged item and it came with 4 T1 cables in the box as well
as documentation and all of the other pretty things you expect in a retail
package. The second thing I noticed is that the card was compatible with a
2U form-factor(That's right, they crammed 4 T1/E1 ports together so it can
fit in a 2U case vertically) This was achieved in-part because the ports are
actually on a fixed daughter card, but it did bring up the thought that they
could actually cram 6 ports on one of these cards :)

Next I started to sort through the documentation and files on their FTP
site. I noticed something I wish Digium cards had: User-upgradable firmware
on the board(I have previously had to return an early version of the T410P
Digium board to get a newer one with newer firmware on it).

Let the installation begin. I started by downloading and installing Asterisk
as usual(zaptel, libpri, asterisk[version 1.0.6]), then I downloaded and
installed Wanpipe release 2.3.2 beta6. I could now see my card and went into
the wancfg utility to configure my card. Here's when it stopped being a
smooth experience. I tried installing it by the asterisk instructions found
on the FTP site(which I found out later were out of date and incorrect) and
eventually it all worked up until the final starting step. The drivers saw
the card, but said nothing was connected to them which I thought was a
strange problem since you don't have to have anything connected to a Digium
card for Asterisk to fully startup. So I emailed tech support and walked
through some reconfiguration steps and then after a few more emails back and
forth it came out that they had a problem with D4/AMI signalling on a RBS
T1(which they say they will have a fix for at some undefined time in the
future). After switching the wanpipe config for the first span to B8ZS/ESF
with a PRI T1 I was able to run ztcfg and asterisk. I placed some test calls
and all went well, at least until I tried hooking up a live RBS(Robbed-bit,
24 full channels not PRI) E&M Wink T1. It turns out that the guys at Sangoma
have never had a customer that used E&M Wink start and accordingly they have
never tested their cards with it, and of course it didn't work. So another
email and call to Sangoma and they started working on a fix. Two days later
they added a Wink for wink start T1s and sent me a new version of the
software. I loaded it and it worked, but all audio and call detects stopped
working if I tried to use more than 10 of the RBS T1 channels, so back to
Sangoma for another new driver version. After a few days, and a few more
driver versions, they came up with one that seemed to fix all of the
problems I was having before so I did my simple stress test of picking up,
hanging up and redirecting to meetme of about 52 Zap lines and all went
well. Now on to the performance testing.

For a performance test, I swapped out an identically configured machine that
had a Digium T405P with my test machine and put it live in company
inbound/outbound call center during off-hours to test(This server usually
handles over 20,000 calls in/out a day with lots of recording going on
across T1s, SIP phones and some IAX2 trunks). This server has two RBS T1s,
one PRI T1 and one Channel Bank. I placed a test call out of the channel
bank through the PRI and then started automated calls from the two RBS T1s
to go into meetme conferences. The performance test ran great and it did
prove that there is reduced CPU usage on a Sangoma board as compared to a
Digium board. For a running time of about an hour the CPU usage was between
30% and 50% lower with the Sangoma board on the identically configured
machine. This was just doing some random calling maintaining 48
conversations across all 4 T1s with calls lasting no longer than 1 minute.
With these results I was very encouraged and decided to put the card into
production.

The production machine that I was replacing is one of our higher-volume
Asterisk servers that routinely handles over 40,000 calls a day. To test
compatibility and reliability of all of the hardware aside from the Sangoma
card, I ran the server in production with a Digium card with no problems
then the next day I put the Sangoma card back in and started it up. About 5
minutes into production everything was going great, the load was very low
for this machine and I was not noticing any channel_walk_lock warnings like
I periodically see on Digium systems. Then at 10 minutes something happened
and the card was not detecting Answers on any calls coming in or going out
on either the PRIs or the RBS T1s. I had to reboot the machine to get it to
start detecting Answers again. This was not good. I thought it was a random
problem so we just started back up again, and then again after about 10
minutes it happened again. I then put the Digium card back in quickly and
rebooted and the server finished out the shift with no problems. The next
day I took the server out of production and started running some more stress
test on it. I couldn't get it to duplicate what had happened the day before
even at higher volumes of calls than it was handling in the live
envorionment. The next week we tried it again in production and the same
thing happened except this time the machine froze. I was pretty sure that
this was an issue with RBS T1s so I put the machine to the task of doing
some PRI call routing between several Asterisk servers and it works just
fine now PRI-only with no problems.

Overall it isn't as easy to install a Sangoma Quad-T1/E1 card on an Asterisk
system as it is to install a Digium card. But the support is very responsive
to installation problems and I'm sure as more Asterisk users try Sangoma
cards, the instructions will be updated more frequently and go more in-depth
into the options offered by Sangoma cards. Throughout my tests I installed
the Sangoma card and drivers several times on a few servers and by the end
it was taking me about 10 minutes extra per install to get the Sangoma cards
and their drivers ready for Asterisk usage.

One minor confusing moment was realizing that Port 1 is on the bottom of the
card unlike Digium where it is on the top. A minor annoyance with the
Sangoma quad T1/E1 card is that you need to create a wanpipe config file for
each span on the card and use another utility to specify the order in which
they are loaded. One more item of note is that you need to wait several
seconds after running 'wanrouter start' before you can start ztcfg or
asterisk, if you do not, the spans may not come up properly.

I am conflicted partially because when you buy a Digium card from Digium you
are directly supporting the company that is the primary contributor to and
maintainer of Asterisk(not to mention the lead-developer and creator of
Asterisk is the CEO) and it is very important to support the core of this
great application. It is important to note however that Sangoma has been
contributing code to GPL Asterisk for a while now(they just recently started
contributing directly as Sangoma) and seems to be doing more development
with Asterisk as they get more Asterisk users as their customers. I do hope
that Digium takes a look at what Sangoma was able to accomplish for roughly
the same price point in a smaller form factor and will hopefully make some
of the same advances in their cards in the future.

I would not recommend a Sangoma card for a beginner user or those who depend
on RBS T1s. Intermediate users and Asterisk Gurus who only use PRI T1s might
want to try one of these cards if only to see if they can squeeze a few more
channels of capacity out of their systems or get better echo cancellation
and control of their card. There is no question that Sangoma has done a lot
to improve on the zapata core hardware design and they will hopefully drive
innovation in this growing market, competition is a good thing.

Installation and test were done on Intel P4 systems running Slackware Linux
10.1 with a custom 2.4.29 SMP kernel.

MATT---