[Users] Clarity on the DISPATCHER module

Hi, I am trying to get an OpenSER instance running with the dispatcher module spreading load amongst several other OpenSER servers. I'm having trouble understanding from the docs and practical application exactly what the dispatcher module does and how to make it do what I want. I want to accept requests and use the dispatcher module to send requests to one of a number of other servers. (I want this setup to scale so I don't want to use the tm module.) Each subsequent request with the same CallId should go back to the same server. Therefore using the hash over the CallId algorithm in the dispatcher module seems like the best choice. I'm running OpenSER 1.0.0 and working off of the configuration in the modules documentation: http://openser.org/docs/modules/1.0.x/dispatcher.html I fixed up a few things that didn't seem to work out of the box such as replacing forward( ) with forward( uri:host, uri:port ). I have several questions. 1. What exactly does ds_select_dst("1", "0") do? I understand the parameters but the module documentation says it "selects a destination from addresses set". OK, so does it return it somehow? How do I get my hands on what it picks? What is an example of a situation where this function would be useful? 2. What exactly ds_select_domain("1", "0") do? I gather it rewrites the host and port with what it gets from the addresses set (which seems more useful than ds_select_dst), but when I run this in practice, _if_ it rewrites the host / port, it always seems to pick the same destination. (in my tests I only get an outgoing INVITE about 10% of the time) It does seem like I want to be using ds_select_domain() though. Can someone point out where my misunderstanding is? I have my configuration copied below. Thanks. -Anders --------------------------------------------------------------------------------------- What I'm expecting: When the first INVITE comes from 10.1.50.30 (Asterisk) to 10.1.50.31, (OpenSER with dispatcher) I want to see an outgoing INVITE from 10.1.50.31 to one of the listed addresses. (10.1.50.[34-37]) What I'm seeing: A tcpdump shows that most of the time all I see is the incoming INVITE. Seemingly random INVITES produce an outgoing INVITE, even when calling the same number. Presumably the only substantive difference is the CallID. openser.cfg: ----------------------------------------------------------------------------- #debug=4 fork=yes log_stderror=no children=4 check_via=no dns=off rev_dns=off port=5060 mpath="/usr/local/lib/openser/modules" loadmodule "maxfwd.so" loadmodule "sl.so" loadmodule "tm.so" loadmodule "dispatcher.so" modparam( "dispatcher", "list_file", "/usr/local/etc/openser/dispatcher.list" ) route { if ( ! mf_process_maxfwd_header( "10" ) ) { sl_send_reply( "483", "To Many Hops" ); drop( ); }; ds_select_domain( "1", "0" ); forward( uri:host, uri:port ); } ----------------------------------------------------------------------- dispatcher.list: ----------------------------------------------------------------------- # gateways 1 sip:10.1.50.34:5060 1 sip:10.1.50.35:5060 1 sip:10.1.50.36:5060 1 sip:10.1.50.37:5060 ----------------------------------------------------------------------- tcpdump shows: ----------------------------------------------------------------------- 07:43:37.216888 IP 10.1.50.30.5060 > 10.1.50.31.5060: UDP, length: 685 .@.@... .2. .2.........INVITE sip:+18666775910@10.1.50.31 SIP/2.0 Via: SIP/2.0/UDP 10.1.50.30:5060;branch=z9hG4bK434da07b From: "+19195551212" <sip:+19195551212@10.1.50.30>;tag=as3a379ead To: <sip:+18666775910@10.1.50.31> Contact: <sip:+19195551212@10.1.50.30> Call-ID: 7dd7978262a876832fc69a4364f89f22(a)10.1.50.30 CSeq: 102 INVITE User-Agent: BandwidthVoice Date: Fri, 03 Feb 2006 12:41:35 GMT Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER Content-Type: application/sdp Content-Length: 202 v=0 o=root 11014 11014 IN IP4 10.1.50.30 s=session c=IN IP4 10.1.50.30 t=0 0 m=audio 8360 RTP/AVP 0 3 8 a=rtpmap:0 PCMU/8000 a=rtpmap:3 GSM/8000 a=rtpmap:8 PCMA/8000 a=silenceSupp:off - - - - ----------------------------------------------------------------------- with no outgoing INVITE. Things seem to be dead. Then I try the same call a few seconds later and I get the outgoing INVITE: ----------------------------------------------------------------------- 07:43:48.695958 IP 10.1.50.30.5060 > 10.1.50.31.5060: UDP, length: 686 .@.@... .2. .2.........INVITE sip:+18666775910@10.1.50.31 SIP/2.0 Via: SIP/2.0/UDP 10.1.50.30:5060;branch=z9hG4bK15490a4e From: "+19195551212" <sip:+19195551212@10.1.50.30>;tag=as302ac772 To: <sip:+18666775910@10.1.50.31> Contact: <sip:+19195551212@10.1.50.30> Call-ID: 531db3695f15035620baae890d555216(a)10.1.50.30 CSeq: 102 INVITE User-Agent: BandwidthVoice Date: Fri, 03 Feb 2006 12:41:46 GMT Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER Content-Type: application/sdp Content-Length: 203 v=0 o=root 11015 11015 IN IP4 10.1.50.30 s=session c=IN IP4 10.1.50.30 t=0 0 m=audio 28484 RTP/AVP 0 3 8 a=rtpmap:0 PCMU/8000 a=rtpmap:3 GSM/8000 a=rtpmap:8 PCMA/8000 a=silenceSupp:off - - - - 07:43:48.696191 IP 10.1.50.31.5060 > 10.1.50.36.5060: UDP, length: 747 E....*@.@..g .2. .2$......S.INVITE sip:+18666775910@10.1.50.36:5060 SIP/2.0 Max-Forwards: 10 Via: SIP/2.0/UDP 10.1.50.31;branch=0 Via: SIP/2.0/UDP 10.1.50.30:5060;branch=z9hG4bK15490a4e From: "+19195551212" <sip:+19195551212@10.1.50.30>;tag=as302ac772 To: <sip:+18666775910@10.1.50.31> Contact: <sip:+19195551212@10.1.50.30> Call-ID: 531db3695f15035620baae890d555216(a)10.1.50.30 CSeq: 102 INVITE User-Agent: BandwidthVoice Date: Fri, 03 Feb 2006 12:41:46 GMT Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER Content-Type: application/sdp Content-Length: 203 v=0 o=root 11015 11015 IN IP4 10.1.50.30 s=session c=IN IP4 10.1.50.30 t=0 0 m=audio 28484 RTP/AVP 0 3 8 a=rtpmap:0 PCMU/8000 a=rtpmap:3 GSM/8000 a=rtpmap:8 PCMA/8000 a=silenceSupp:off - - - - ----------------------------------------------------------------------- any help greatly appreciated.