Remember that the SIP protocol has a requirement on both transactions and dialogs (if you do accounting) to go through the same server.  If you have stateless proxies, no problem, but we are normally talking about stateful proxies.
I know people have experiemented with vrrp.
http://sourceforge.net/projects/vrrpd/

You would probably implement the peers with either usrloc-cl against a mysql cluster or by using t_replicate.
g-)


Natambu Obleton wrote: 
I bet an Anycast setup with multiple servers having the same ip address
pointing to the same Mysql database would work. I have done it with mail
servers and dns servers.

http://en.wikipedia.org/wiki/Anycast#Reliability_of_anycast


Natambu Obleton
Network Engineer
FastTrack Communications
nobleton@fasttrackcomm.net
(970) 247-3366 office
(970) 247-2426 fax
 
-----Original Message-----
From: Greger V. Teigre [mailto:greger@teigre.com] 
Sent: Tuesday, September 19, 2006 11:55 PM
To: Natambu Obleton
Cc: 'Vitaly Nikolaev '; serusers@iptel.org
Subject: Re: [Serusers] Scaling SER

Actually it depends on the NAT implementation. There are four generally 
known/defined types (in STUN), but a lot of variants.  When we talk 
about the NAT problem, we always talk about the worst-case, which is a 
symmetric NAT, i.e. only packets from src ipA:portB will be allowed 
through and only if a previous packet has been going out to dst 
ipA:portB not longer ago than a defined time-out. Some NATs have timeout 
of 60 minutes, others (could be) as low as 30 sec.
g-)

Natambu Obleton wrote:
  
Ohh.. I thought the keepalives would allow other ip address, than the one
that originally opened the connections, to send in. 

I guess that wouldn't be very secure would it.... :)


Natambu Obleton
Network Engineer
FastTrack Communications
nobleton@fasttrackcomm.net
(970) 247-3366 office
(970) 247-2426 fax
 

-----Original Message-----
From: serusers-bounces@lists.iptel.org
[mailto:serusers-bounces@lists.iptel.org] On Behalf Of Vitaly Nikolaev 
Sent: Tuesday, September 19, 2006 8:53 AM
To: serusers@iptel.org
Subject: RE: [Serusers] Scaling SER

To extend Juha's info:

Only SER server that just received SIP packet from SIP device (either
register or keepalive) can send something  back in case of NAT

For example you have SER1 and SER2, client A registered on SER1 and
client B on SER2, when client B sends call to client A it will first hit
SER2 then SER2 to according to replicated location table will try to
send it to client A straight and fail in case client A behind the nat
(which is quite often in real world)

Trick is to teach SER2 to forward call to SER1 when needed, it can be
done when you use b2bua that looks to same location table for example
(ser need to be taught to place its IP also in same table).

Can not give you exact howto but can give (out of list) some references
to  commercial software if interested.


-----Original Message-----
From: serusers-bounces@lists.iptel.org
[mailto:serusers-bounces@lists.iptel.org] On Behalf Of Juha Heinanen
Sent: Tuesday, September 19, 2006 8:52 AM
To: Andrey Kuprianov
Cc: serusers@iptel.org
Subject: Re: [Serusers] Scaling SER

Andrey Kuprianov writes:

 > mediapoxy'll handle it.

mediaproxy does not forward sip requests.

-- juha
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