Message

On Apr 10, 2005 11:03 PM, Tina <kramarv@yahoo.com> wrote:

Paul,

thanks a lot, it helps a lot. The thing I do not understand - how you are going to solve call-id stickness (see my another post). Since we're also use LVS I had to find something proprietary, I am afraid this is not a best solution, but the only I have today.

KRs,

Tina

Java Rockx <javarockx@gmail.com> wrote:

Tina,

I really don't know how the LVS server is configured because our network guy that we acquired from RedHat set all that stuff up. I do know that we basically have this set up:

I hope the formatting goes well :-)

+-----------+     +----------+     +-------+    +---------+   +--------------------+
| internet |------| Cisco |------| LVS |-----| Cisco |----| Application     |
| cloud    |      | 3600   |      |         |     | 3600 |    | & DB Servers |
+-----------+     +----------+    +--------+    +---------+   +--------------------+

So the "Application & DB Servers" box represents multiple servers (all are dedicated to their service). These include SER, MySQL, Apache, configuration management, monitoring, RTP proxies, etc.

MySQL is active-active so we have two-way replication. We only have 2 MySQL servers. And this is all we plan on ever having as MySQL is more than capable of handling anything ser can throw at it (given the right hardware).

Each ser server is 100% oblivious to other SER servers except for when handling REGISTER messages. Here is basically the ser.cfg for each SER server:

listen=10.3.0.221 # this will be 10.3.0.222 on the peer sip proxy
modparam("usrloc", "db_mode", 1) # write-through

route {
       if (method=="REGISTER") {
            if (src_ip==10.3.0.221) { # ip of peer ser proxy
                  save_memory("location");
                  break;
            } else {
                  save("location");
                  t_replicate("10.3.0.222");
                  break;
            };
       };
}

We have identifed a deficiency in the usrloc module urecord.c file whereby when using write-though mode the save_memory() function still attempt to update MySQL. This is a very bad thing because it causes a primary key violation on the location table.

Yesterday I posted a patch to serdev to fix this, but today we identified another case where save_memory() tried to insert in to the location table. I'll post a revised patch to serdev as soon as I get a chance.

So here is what happens. Assume I have two sip routers and two MySQL servers as:

sip-01 is 10.3.0.221
sip-02 is 10.3.0.222
db-01 is 10.2.0.21
db-02 is 10.2.0.22

Now let's just assume that sip-01 is connected to db-01 and sip-02 is connected to db-02.

When a SIP UA connects to a sip router (via LVS), assume sip-01 in this example and REGISTERs, sip-01 will call save("location") which updates/inserts to the location table. sip-01 then calls t_replicate to sip-02.

sip-02 recieves the REGISTER message and calls save_memory("location") to update its in-memory cache only. It should never hit db-02.

Now db-01 eventually (within a second or two) replicates to db-02 and now sip-02 is good to go, even in the event of a restart.

Our difficulties mostly surrounded the fact th at ser was inserting the physical IP of eth0 on the server as the top VIA rather than the VIP as required. We solved this by using record_route_preset() and passing the VIP as the IP. We also had to bring up a dummy interface in order to get ser to honor the VIP.

Hope this helps.

Regards,
Paul

On Apr 8, 2005 7:19 PM, Tina <kramarv@yahoo.com> wrote:

Paul,

we are using LVS as well. It creates template connection according to source Ip (e.g. UAC) and forwards to one of the tunneled IP. I tested this a couple of weeks ago, ser was happy and inserted VIP into via header, the only issue is to route the calls into right server.

I agree, there is no such thing as SIP-level clustering. However, how would you solve location problem by DB replication - 1) usrloc does not update from DB....2) even though, I am afraid it can become bottleneck and lock down users ...

KRs,

Tina

Java Rockx <javarockx@gmail.com> wrote:

See my inline comments.

Regards,
Paul

On Apr 8, 2005 1:08 PM, Greger V. Teigre <greger@teigre.com> wrote:

Hi Tina,

> I enjoy reading your posts, thanks a lot for the great work you are
> doing for ser users!

Thanks :-)

> I am going to consider that kind of scenario as well (load balancer
> returning Virtual IP address). I think for such configuration server
> side has to keep session information and always forward a call to the
> right server.

I believe the load balancer can be in front and transparantly translate addresses in the SIP messages:

User agent always sees a.b.c.d

                         |

Load balancer with public IP a.b.c.d

       |                               |

ser1 (10.0.0.2)          ser2 (10.0.0.3)

Paul: You have a similar load-balancing solution, right? Do you use a commerical load balancer that you can reveal the name of? :-)

Our platform is 100% open source. Our load balancer is LVS. I have no idea how it actually works. One if our engineers from RedHat set all that networking stuff up and it's way beyond me.

The load balancer need to understand SIP (sort of) and use something (ex. IP address of user agent) to select SER server to send to and rewrite incoming to 10.0.0.2 and 10.0.0.3 respectively and outgoing to a.b.c.d. ser1 and ser2 will happily believe they are alone and communicate directly with user agent using their own private addresses. Both should know about all users (usrloc). Paul just recently posted a small patch for a setup where they use two-way replication between two

That small patch will need a slight revision. We discovered through further testing that that patch only fixed attempts to INSERT into the location table. We didn't cover the UPDATE route, unfortunately. I believe Andrew has that patch done and is testing it. So I'll post it to serdev as soon as we know it works - possibly later today.

mysql servers and where each SER instance will save all REGISTERs it receives from user agents, but only save to memory those replicated from the other SER peer. Klaus pointed out that the same can be done by not doing mysql replication, but have one DB for each SER and just use t_replicate() and save_noreply() (for two servers, for more than two you need to use forward_tcp()).

I have heard complaints that this approach will generate too much network traffic. Also, t_replicate() does not guarantee delivery of the replication (forward_tcp is better, but not fool proof). So, the "best" solution would probably be to hope that Paul's

I fully agree. Replication at the sip proxy level, IMHO, is not a good idea. From a purist point of view, replication is not a function of a SIP router - nor should it be. It is a function of the database and we believe that the MySQL replication is a better approach from a speed and reliabilty point of view - not to mention that it simplifies the tasks of the sip router.

recent TCP/UDP patch for network access to FIFO commands get included in the CVS. Then, a new replication module should use XMLRPC or whatever protocol the patch is using to forward (in a guaranteed mode) the usrloc information, which then would be injected directly into SER's memory, just like save() would, and of course in whatever db_mode you would like. The replicaton module would have to keep a queue (of course, flushed to a DB or something) in case of network problems, so that the replication would be done (sooner or later) regardless of problems.

    Of course, this is a major undertaking, so for most replication scenarioes, I would think the forward_tcp() + save_noreply() would work just fine.



g-)

> "Greger V. Teigre" <greger@teigre.com> wrote:
> I was thinking about a load balancing scenario where the load
> balancer will replace the IP addresses.
> g-)
>
> ---- Original Message ----
> From: Tina
> To: Greger V. Teigre
> Sent: Wednesday, April 06, 2005 09:45 PM
> Subject: Re: [Serusers] still no help - usrloc synchronization
>
>> Thank you for givingme the scenario with "restricted IP" NAT, I am
>> starting to find some acceptable solution.
>> Unfortunately, "one-public-IP" approach is not free from problems
>> also. If your SIP router inserts this "one-public-IP" into the VIA
>> header, the reply routing goes via wrong SIP server...
>> If your SIP server inserts its real-IP-address - the scenario
>> mentioned above is s till not resolved.
>> Any comments?
>> Tina
>>
>> "Greger V. Teigre" <greger@teigre.com> wrote:
>> See inline.
>>
>>> If you use DNS server for load balancing... the client receives one
>>> of your domain IP addresses according to SRV. I don't see the
>>> problem
>>> with a call here, cause UAC asks t! he address only once (before
>>> sending INVITE). UAC already has the IP for BYE/reINVITEs. So why
>>> would you replicate INVITEs?
>>
>> I would never replicate INVITEs, I would just make sure that they are
>> proxied through the correct SER server (i.e. IP).
>>
>> The problems depends on your setup. If you have SERs with different
>> IPs, ex UA1 has registered with server A and UA2 ha s registered with
>> server B: If UA2 wants to call UA1 and UA is behind an IP restricted
>> NAT, server A is stored in the NAT table of the NAT in front of UA1.
>> If server B sends an INVITE to UA1, the INVITE will be refused by
>> UA1's NAT.
>>     This is why a "one public IP" in front of a load balancing
>> cluster probably is a good way to go.
>>
>>> If you use IPVS/LVS... I believe you can force SER to insert it's
>>> public IP into VIA,! so there is no problem with replies. With
>>> regard
>>> to another requests, I believe load balancer keeps connection
>>> template, then when another request comes it would be forwarded to
>>> the same ser.
>>
>> Yes. There are different "keys" to use to load balance SIP messages.
>> One good way from a NAT point of view is to use originating IP
> > address. What you must remember is that the problem is not on the
>> server side, but on the client side. The NAT will in many situations
>> stop incoming UDP packets if the originating ip:port is not already
>> stored in the NAT table. The Via header does not matter for the NAT.
>> g-)
>>
>>> Any comments?
>>>
>>> "Greger V. Teigre" <greger@teigre.com> wrote:
>>> Yes, I believe that is so. But still you get a problem if the NAT is
>>> restricted, port-restricted or symmetric... The best would be to
>>> load>> balance and always make sure that a given client is handled
>>> through a given
>>> SER (REGISTER and INVITEs). That includes forwarding INVITEs from
>>> one
>>> SER to
>>> another... OR you must load balance in front of your servers with
>>> one
>>> common
>>> public IP.
>>> g-)
>>>
>>> Matt Schulte wrote:
>>>> Ack, I didn't even think about NAT. Would these be added before it
>>>> gets sent off to the second proxy? ie:
>>>>
>>>> if (!src_ip==blah.netlogic.net) {
>>>> add_rcv_param();
>>>> t_replicate("blah.netlogic.net", "999");
>>>> };
>>>>
>>>> -----Original Message-----
>>>> From: Greger V. Teigre [mailto:greger@teigre.com]
>>>> Sent: Tuesday, April 05, 2005 7:49 AM
>>>> To: Matt Schulte; kramarv@yahoo.com
>>>> ! ; Cc: serusers@lists.iptel.org
>>>> Subject: ! Re: [Serusers] still no help - usrloc synchronization
>>>>
>>>>
>>>> Well, you still have the NAT issues unless you do load balancing
>>>> and your
>>>> SER servers have the same public IP.
>>>> Have you looked at 0.9.0 nathelper function add_rcv_param() ? It
>>>> will add received info to the contact header for the other SER to
>>>> process. Haven't really tried yet...
>>>> g-)
>>>>
>>>> Matt Schulte wrote:
>>>>> I'm starting to lean this direction, using t_replicate and all. I
>>>>> could never get usrloc (db mode) to function properly..
>>>>> t_replicate is
>>>>
>>>>> a dirty but very effective workaround.
>>>>>
>>>>> -----Original Message-----
>>>>> From: Greger V. Teigre [mailto:greger@teigre.com]
>>>>> Sent: Saturday, April 02,! 2005 1:33 AM
>>>>> To: kramarv@yahoo.com
>>>>> Cc: serusers@lists.iptel.org
>>>>> Subject: Re: [Serusers] still ! no help - usrloc synchronization
>>>>>
>>>>>
>>>>> Have a look at this thread:
>>>>> http://lists.iptel.org/pipermail/serusers/2005-January/014669.html
>>>>> g-)
>>>>>
>>>>> Java Rockx wrote:
>>>>>> Tina,
>>>>>>
>>>>>> I thought I saw you post the other day that you did not want to
>>>>>> use t_replicate(), however, this is probably your best bet to
>>>>>> getting this
>>>>>
>>>>>> to work, IMHO.
>>>>>>
>>>>>> Regards,
>>>>>> Paul
>>>>>>
>>>>>> On Apr 1, 2005 4:08 PM, Tina wrote:
>>>>> ! >>
>>>>>> ! ;> Hi, please help me, I'm stuck with it!!!!!
>>>>>>> I am trying to set up several sers with a shared MySQL database
>>>>>>> for location service.
>>>>>>>
>>>>>>> I set in each ser.cfg:
>>>>>>>
>>>>>>> modparam("usrloc", "db_mode", 2)
>>>>>>> modparam("usrloc",
>>>>>>> "db_url","sql://ser:heslo@192.168.25.163/ser")
>>>>>>>
>>>>>>> and the servers are not synchronized.
>>>>>>> The I set
>>>>>>> modparam("usrloc", "db_mode", 2)
>>>>>>>
>>>>>>>
>>>>>>> made UAC (Xlite) register to one of the servers.
>>>>>>> I see it via usrloc, but there is no record in "location" mySQL
>>>>>>> table....So others do not see the client and I'm unable to make
>>>>>>> calls....
>>>>>>>
>>>>>>>
>>>>>>> Please help how to work with usrloc and mySQL...
>>>>>>>
>>>>>>> Tina,
>>>>>>> software engineer
>>>>>>>
>>>>>>> ________________________________
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>>>>>>>
>>>>>>
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