[Serusers] Loadbalancing / high availability

E. Versaevel erik at infopact.nl
Tue Dec 7 08:53:49 CET 2004


Hello,

Do you use SER for routing / authorizing in any way or do you only use
asterisk for that?
Does the Foundry ServerIron take care of sip sessions ending up at the same
SER machine (by looking at the called for example)?

And why not use the ServerIron directly for loadbalancing the asterisk
boxes?

Btw, I can't seem to find the dispatcher module either.


Kind regards,

E. Versaevel

-----Oorspronkelijk bericht-----
Van: serusers-bounces at iptel.org [mailto:serusers-bounces at lists.iptel.org] Namens
Michael Shuler
Verzonden: dinsdag 7 december 2004 4:36
Aan: 'Jiri Kuthan'; 'Matt Schulte'; serusers at lists.iptel.org
Onderwerp: RE: [Serusers] Loadbalancing / high availability


I was not aware that there was a dispatcher module (I don't see any docs for
it on the site).  


The Foundry load balances the SIP messages as they come from VoIP phones on
the Internet over the cluster of SER boxes which then balance the "sessions"
over ast_data patched Asterisk boxes (since a "session" must continuously go
to the same Asterisk box to maintain call state within Asterisk).  To
balance the session from SER over the Asterisk boxes I am using round robin
DNS where ast.bwsys.net actually expires every second through ast0, ast1,
ast2, etc.  So SER does a forward("ast.bwsys.net") on the initial INVITE
messages from the VoIP phones.  The Asterisk boxes conveniently replaces
ast.bwsys.net with their real IP and SER uses the real IP on all future
messages automatically until that "session" is done.  The next INVITE from
the same VoIP phone is then put through the same round robin DNS and may end
up on a different Asterisk server next time.


----------------------------------------

Michael Shuler, C.E.O.
BitWise Communications, Inc. (CLEC) And BitWise Systems, Inc. (ISP)
682 High Point Lane
East Peoria, IL 61611
Office: (217) 585-0357
Cell: (309) 657-6365
Fax: (309) 213-3500
E-Mail: mike at bwsys.net
Customer Service: (877) 976-0711 

> -----Original Message-----
> From: Jiri Kuthan [mailto:jiri at iptel.org] 
> Sent: Monday, December 06, 2004 1:27 AM
> To: Michael Shuler; 'Matt Schulte'; serusers at lists.iptel.org
> Subject: RE: [Serusers] Loadbalancing / high availability
> 
> 
> What is exactly role of ServerIron when SER does load balancing?
> Are you using SER's dispatcher module?
> 
> -jiri
> 
> At 05:37 PM 12/1/2004, Michael Shuler wrote:
> >We use a Foundry ServerIron XL and it seems to work fine.  
> We do not use SER
> >as a stateful proxy though.  SER is basically a SIP message 
> load balancer
> >across our Asterisk boxes.
> >
> >----------------------------------------
> >
> >Michael Shuler, C.E.O.
> >BitWise Communications, Inc. (CLEC) And BitWise Systems, Inc. (ISP)
> >682 High Point Lane
> >East Peoria, IL 61611
> >Office: (217) 585-0357
> >Cell: (309) 657-6365
> >Fax: (309) 213-3500
> >E-Mail: mike at bwsys.net
> >Customer Service: (877) 976-0711 
> >
> >> -----Original Message-----
> >> From: serusers-bounces at lists.iptel.org 
> >> [mailto:serusers-bounces at lists.iptel.org] On Behalf Of Matt Schulte
> >> Sent: Wednesday, December 01, 2004 7:42 AM
> >> To: serusers at lists.iptel.org
> >> Subject: RE: [Serusers] Loadbalancing / high availability
> >> 
> >> 
> >> 
> >> I'm curious what brand load balancer you would use, would it be IP
> >> based. We tried out a Cisco SLB and had no luck, mainly 
> >> because it would
> >> NAT to the servers (more trouble than it's worth?). We were 
> >> thinking of
> >> using a heartbeat type failover, similar to what you would do 
> >> for MySQL:
> >> 
> >> http://linux-ha.org/download/
> >> 
> >> Has anyone tried this method? We're more concerned about the high
> >> availability than anything.
> >> 
> >> -----Original Message-----
> >> From: E. Versaevel [mailto:erik at infopact.nl] 
> >> Sent: Wednesday, December 01, 2004 7:24 AM
> >> To: serusers at lists.iptel.org
> >> Subject: [Serusers] Loadbalancing / high availability
> >> 
> >> 
> >> Hello,
> >> 
> >> I was wondering if it is necessary for a SIP packet from a 
> >> specific call
> >> to always go through the same server?
> >> 
> >> For instance, if you have a load balancer distributing 
> requests over a
> >> few servers, it is possible that an INVITE ends up on 1 
> >> server while the
> >> following INVITE with the credentials ends up on another, 
> >> would this be
> >> a problem (ie, break the authorization) or should you use 
> a SIP aware
> >> loadbalancer for this (who looks at the callid for 
> example)? Assuming
> >> the ser servers are setup to use the same userdatabase (and 
> >> t_replicate
> >> to eachother) the picture would be something like this:
> >> 
> >>                       |
> >>                 --------------
> >>               |loadbalancer|
> >>                 --------------
> >>                    |
> >>                    |
> >>           --------------------
> >>           |          |         |
> >>       -------   -------   -------
> >>       |     |   |     |   |     |
> >>       | ser1|   | ser2|   | ser3|
> >>       |     |   |     |   |     |   
> >>       -------   -------   -------
> >> 
> >> If you setup the servers with the same IP as the load 
> >> balancer and stop
> >> them from replying to ARP requests for that IP, replying back 
> >> thru a NAT
> >> should not be a problem.
> >> 
> >> Just thinking out loud, I could use SER for the load balancing and
> >> t_relay the packets, however that would require some 
> >> tampering with the
> >> VIA records (and I should use a reply to via in that case to the
> >> original IP the SIP request came from, eg not the load 
> balancer) this
> >> way outgoing SIP traffic would not have to go thru the ser 
> >> loadbalancer
> >> again to get out, hmm, it might even be possible to use a 
> route-record
> >> header to get the packets back at the correct server...
> >> 
> >> 
> >> Kind regards,
> >> 
> >> E. Versaevel
> >> 
> >> _______________________________________________
> >> Serusers mailing list
> >> serusers at lists.iptel.org http://lists.iptel.org/mailman/listinfo/serusers
> >> 
> >> _______________________________________________
> >> Serusers mailing list
> >> serusers at lists.iptel.org
> >> http://lists.iptel.org/mailman/listinfo/serusers
> >> 
> >
> >_______________________________________________
> >Serusers mailing list
> >serusers at lists.iptel.org
> >http://lists.iptel.org/mailman/listinfo/serusers
> 
> --
> Jiri Kuthan            http://iptel.org/~jiri/ 
> 

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