asterisk users - Mar 2006 - Feedback from VON expo! Info on * HA andPolycomphone!!

Great Email. I'm going to respond to some of the points.

"Q:  What are the plans for HA?
    A:  With a configuration using DNS-SRV and DUNDi, you can create a 
pretty resiliant setup now."

That's BS. Last time I checked, Asterisk's support of SRV was to only
grab the first SRV entry. Period. If it doesn't try any more SRV hosts after
the first fails, just exactly how is that redundant?

"Q:  What the deal with the limit on the number of people you can
monitor 
for presence?
    A:  There is no limit in the phone.  This is an Asterisk limitation."

That's BS too. I have an email thread from a Polycom employee where they
recognised it was a Polycom issue and was told they might have an newer version
of the SIP software out to address this by summer. Still can't fathom why
this takes months to fix, but anyway...

"Q:  Whats the best way to program the phone to handle failover?
    A:  Use a DNS-SRV address for the primary server.  When the phone 
queries the DNS server, it will receive a list of all the possible
servers "

This is broken to some degree. When the phone refreshes it's cache, and
grabs the list of SRV servers again, it will continue to use them in the same
manner until it refreshes it's cache again, or there is a failure, even when
all SRV hosts have the same priority and weight. It should round robin in this
case.

And in regards to Asterisk HA, and approach #2. If you have your SER boxes use
the send() command to stateless forward registrations, you can send
registrations from the phones to ALL your Asterisk systems so that every
Asterisk box knows about every phone, and every Asterisk box can route calls
from/to any phone.

Doug


-----Original Message-----
From: Jim Houser [mailto:jhouser@trustamerifirst.com]
Sent: Thursday, March 16, 2006 7:50 AM
To: 'Asterisk Users Mailing List - Non-Commercial Discussion'
Subject: RE: [Asterisk-Users] Feedback from VON expo! Info on * HA
andPolycomphone!!


Gabe.

  Who was the call-center program from?

Thanks,
Jim

-----Original Message-----
From: asterisk-users-bounces@lists.digium.com
[mailto:asterisk-users-bounces@lists.digium.com] On Behalf Of Gabriel
Afana
Sent: Thursday, March 16, 2006 2:38 AM
To: Asterisk Users Mailing List - Non-Commercial Discussion
Subject: [Asterisk-Users] Feedback from VON expo! Info on * HA and
Polycomphone!!


Hey group,
    I just got back from the VON expo.  It was insane....there were so
many 
companies there.  The #1 thing ***EVERY*** company focused on was 
"convergance" - getting all your communication devices to intergrate
with 
eachother.  There were some nifty products out there that did some cool 
stuff :-)

    Of course Digium/Asterisk was there and I had a list of questions
for 
them.  I went by several times asking more and more questions...by the
last 
visit, these guys were running from me because I was driving them nuts
:-) 
Here are all the questions I asked them (this is not word for
word...just a 
summary):

    Q:  What are the plans for HA?
    A:  With a configuration using DNS-SRV and DUNDi, you can create a 
pretty resiliant setup now.

    Q:  What about failover without losing a call
    A:   IBM has been able to make asterisk do this.  However, at this
time 
we are not working on any solution to offer this as part of the program.

    Q:  Do you plan on offering support for other distros for Asterisk 
Business Edition?
    A:  [uncertain answer]  Not really sure...maybe SuSE...not sure

    Q:  When is asterisk going to fully support video?
    A:  Asterisk can complety support video using H.261, H.263 and we 
recently added support for H.264

    Q:  What do you recommend as the best solution for HA?
    I got two different answers for this from two different people
there. 
Both made good sense and are basically what everyone is doing now.  Here

both approaces are in a nut-shell:

    Approach 1 (seemed to be the preferred method):  Use DNS-SRV lookups
for 
all registrations.  This will distribute the calls among the * servers. 
Next, you configure your servers using regexten and DUNDi.  You use
regexten 
to dynamically create the "exten => 1234,1,NoOp" when a phone
registers
with 
that server.  Then when a call comes in, you use DUNDi to try to
complete 
the call locally.  If the phone is not registered to that server, then
do a 
DUNDi lookup to find the server that the phone is registered to and then

pass the call over IAX to that server to take it to the phone.  Of
course 
the phones will need to have a short registration expiration so they
update 
frequently because if the server they are registered to crashes, until
it 
re-registered, no server can access it.  But by doing this, the phone
will 
re-register to another server and then the next DUNDi lookup will then
go to 
this new server.  I asked about the load of having many phones
registering 
frequently and he said it is no big deal at all.  He also said it was
very 
important to make sure cache is disabled in DUNDi!!!  Each call that is
made 
should result in a new query.  This will ensure the calls are not
getting 
old cached info which may no longer be accurate.

    Approach 2: Use a SER box to handle all registrations.  The SER box
will 
take care of distributing the load between the * boxes.  You do not use 
DUNDi or regexten in this case.  Just let each * box function on its
own. 
If one of the servers fails, SER will not use it to terminate calls.
Sinces 
the phones are registering to SER, and all incoming calls will be routed
to 
SER, you do not need to worry much about the * boxes.  You just need to
make 
sure you have your SER boxes in a cluster to fail-over in the event of 
failure.

    Overall theme of the Asterisk stand:  selling third-party products.
In 
the there section, Digium had 10 seperate vendors that have teamed with
them 
to sell special programs/products/services that intergrate with
Asterisk. 
One was a call-center program, another was a resellers package, another
delt 
with firewalls and NAT, another for voice recognition, another was Intel

(that has partnered with Digium to offer drivers in the ABE for the
intel 
cards), another was some email, fax, chat, presence, etc. kind of box
that 
sits in front of * to combine all these services....and some others I
dont 
remember.  It felt like I was walking into an infomercial!


    I also spoke with Polycom guys a great deal and asked many
questions:

    Q:  Do you plan on offering 10/100/1000 ports on the phones?
    A:  Yes, in the near future

    Q:  Do you plan on offering a standard phone jack for failover
purposes?
    A:  No, we have no talks of this.  However, I will take this idea to
the 
production development team.

    Q:  What is the "services" button ever used for?
    A:  This is only operable in the 601 and is used to launch the XML 
browser.  We have partned with many companies to offer you sports,
weather, 
stock, movie ticket info...etc that can be fed directly to the phones 
screen.

    Q:  What the deal with the limit on the number of people you can
monitor 
for presence?
    A:  There is no limit in the phone.  This is an Asterisk limitation.

    Q:  How can you get the name of the person you are calling to appear
on 
the phone instead of their extension? (they had a demo of their phones
there 
and they were doing this!!!)
    A:  You enter the information into the phone book directly via the
XML 
script loaded from the bootserver.  Since all the phones will use the
same 
bootserver to fetch the XML script, they will all have each others
extension 
numbers and associated names.  When you call another extension, their
name 
will then appear.

    Q:  When the phone is unable to make a call through the primary
server 
and it redirects to the secondary server, does it just make the call or
does 
it also register with the secondary server?
    A:  No, it will not register with the secondary server
automatically. 
This is done on purpose to help reduce unneccessary registrations.

    Q:  Whats the best way to program the phone to handle failover?
    A:  Use a DNS-SRV address for the primary server.  When the phone 
queries the DNS server, it will receive a list of all the possible
servers 
to send the call to.  The phone will try to register to the first
server; if 
this fails, it will go to the second server...and so on through the list

until it can register.  Once it is registered with a server, if that
server 
fails (or the phone is unable to reach that exact server for some
reason), 
the phone will *not* go to the secondary server!!!  The results of the
DNS 
lookup are saved on the phone so if the call doesn't go through to the 
server its registered with, it will recall the saved list of servers 
available and go through that list.  Because of this, there is no need
to go 
to the secondary server section since it will simply loop through all
the 
servers it received during the DNS-SRV lookup.


    I am sure there were many things I left out or forgot to say.  If I 
remember, I'll be sure to post them.

- Gabe


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Peter,
 
Sorry, can't do inline replies with web based Outlook.
 
Yes, I know... I'd say that if the phone wasn't available between the
period the server went down, and the time it re-reregistered, then it's not
a HA solution.
 
I discussed with the people that make the decisions this evening, and having
downtime like that is not an option. You'd also have no reliable BLF
functionality as the subscribe and notify messages would be spread amongst
multiple systems and just plain wouldn't work.
 
Can you imagine what sort of traffic, say even 1000 phones re-registering every
minute would be like? That's SEVENTEEN new registrations per second.
 
Doug
 

	-----Original Message----- 
	From: Peter Bowyer [mailto:peeebeee@gmail.com] 
	Sent: Thu 3/16/2006 11:50 PM 
	To: Asterisk Users Mailing List - Non-Commercial Discussion 
	Cc: 
	Subject: Re: [Asterisk-Users] Feedback from VON expo! Info on * HA
andPolycomphone!!
	
	

	On 17/03/06, Douglas Garstang <dgarstang@oneeighty.com> wrote:
	> David,
	>
	> How's DUNDi make this redundant? The way I understand it, a phone is
only ever registered to a single Asterisk box at a time. If that Asterisk box
where to fail, callers lose the ability to contact users that where registered
on that box.
	
	Assuming you're using regcontext/regexten, if a phone isn't found
	locally then a DUNDi switch will allow it to be found elsewhere -
	assuming it has re-registered. It will only be unavailable during the
	re-registration interval.
	
	You need to go and try this, not keep posting about how you think it
	won't work. Then we can help you get it going.
	
	--
	Peter Bowyer
	Email: peter@bowyer.org
	Tel: +44 1296 768003
	VoIP: sip:peter@bowyer.org
	VoIP: *5048707000@sipbroker.com
	FWD: **275*5048707000
	VoipTalk: **473*5048707000
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Huh? Phones do a NAPTR/SRV lookup in a specified domain to get a list of SRV
records to use. The phones don't query the DNS server every time they make a
call... they have a cache. You also run primary and a secondary (or two primary)
dns servers. It's a simple scalable solution. It's a shame Asterisk
doesn't support it.
 
Doug.

	-----Original Message----- 
	From: Aaron Daniel [mailto:amdtech@shsu.edu] 
	Sent: Sat 3/18/2006 6:39 PM 
	To: Asterisk Users Mailing List - Non-Commercial Discussion 
	Cc: 
	Subject: Re: [Asterisk-Users] Feedback from VON expo! Info on * HA
andPolycomphone!!
	
	

	Seems to me that it's more logical for the phones to know what their 
	SRV records are than the server.  You shouldn't rely on the dns to 
	ensure that your system is redundant.
	
	Aaron
	
	On Mar 16, 2006, at 1:03 PM, Douglas Garstang wrote:
	
	> I know someone who's at VON this week. Apparently Mark Spencer was 
	> up there talking about how Asterisk supports SRV. Sounds like 
	> vaporware to me.
	>
	>> -----Original Message-----
	>> From: David Thomas [mailto:punknow@gmail.com]
	>> Sent: Thursday, March 16, 2006 11:54 AM
	>> To: Asterisk Users Mailing List - Non-Commercial Discussion
	>> Subject: Re: [Asterisk-Users] Feedback from VON expo! Info on * HA 
	>> and
	>> Polycomphone!!
	>>
	>>
	>> In regards to HA...
	>>
	>> SER is definitely a good option, but it does require the extra
	>> hardware to have at least 2 boxes that can failover on each other. I
	>> would user OpenSER however (better documentation and mor features).
	>>
	>> I couldn't agree more that Asterisk should FULLY support DNS-SRV.
The
	>> solution seems to work great for phones and ATA's. This would be a
	>> good item to create a bounty for.
	>>
	>> I have only two boxes right now, so it seems like my only HA options
	>> are the dreaded DUNDi setup or a active/passive failover with
	>> linux-HA.
	>>
	>> David
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