[Serusers] forward() and t_relay() differences

[Jiri Kuthan]

At 01:04 AM 10/5/2004, Michael Shuler wrote:
>My intent is to do SIP load balancing using a layer 4 hardware switch (such
>as a Foundry ServerIron XL) or a layer 4 software switch (such as
>UltraMonkey).
>
>Since SER *could* operate in a completely stateless mode it could serve as a
>per packet proxy in front of a series of stateful feature servers such as
>Asterisk.  A L4 device by itself would not be enough and a stateless MUST be
>in front to do the actually balancing because of SIP's flaw/design of
>containing routing information throughout the packets life.  

I don't think that this specific issue is SIP design flaw. It is coming
from the proxy mode which is useful for many reasons. Achieving consistency
with a proxy and load-balancer is not as easy as for banal request-response
apps like web.



>It would have
>been nicer if it only carried a source and destination and worked more like
>TCP/IP but unfortunately it is what it is.
>
>Anyway, I about have everything working and I only seem to have a small
>issue when the second SER server comes online with some strange message
>passing between them.  Most of it I believe is caused by my lack of
>understanding of how SER makes some decisions on where to send things.  

It depends on what you mean by things. If you mean log error than these
are sent to syslog. If you mean replies, their destination is governed
by RFC3261 and rport extensions. If you mean proxied requests, than
the destination is governed by routing script.

>I
>think what would help is if I setup a "work in progress" web site that would
>show all my config files and the layout of the whole thing along with an
>explanation of why I decided to do what I did.  I should have it up later
>today or tomorrow.
>
>----------------------------------------
>
>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, October 04, 2004 5:42 PM
>> To: Michael Shuler; serusers at lists.iptel.org
>> Cc: jan at iptel.org
>> Subject: RE: [Serusers] forward() and t_relay() differences
>> 
>> 
>> At 07:50 PM 10/4/2004, Michael Shuler wrote:
>> >Sorry if that first line sounded snotty, I didn't mean it 
>> that way.  I
>> >didn't read it until after I sent it.  What I meant to say 
>> was thank you for
>> >the response.
>> 
>> you are very welcome.
>> 
>> >  I had already been through the docs though and found that too
>> >but I was still seeing the following problem..
>> 
>> I am interestd in more feedback on load-balancers. To my 
>> knowledge, it is
>> a technology which has some conflicts with SIP protocol and 
>> those LBs that
>> try to fix the problems using built-in SIP awareness don't do 
>> necessarily
>> any better. We are working on a SER built-in load-balancing 
>> architecture
>> but that's still work in progress.
>> 
>> -jiri
>> 

--
Jiri Kuthan            http://iptel.org/~jiri/