[SR-Users] Dispatcher Load Balance with SIP Trunk

[warawich]

Hello,

I would like to do a load balance between Asterisk SIP trunks.  You can see
a diagram from this link:
https://drive.google.com/file/d/1Qy66L5rQCfxysYQpSd2-ek_8-by0T8PR/view?usp=sharing

SIP Packets capture log:
https://drive.google.com/file/d/1CHGUOwoRDAC93MMBtyfa8gBISKIVC-ng/view?usp=sharing


Details
1. Asterisk1 makes SIP trunk connection with Kamailio.
2. Kamailio makes SIP trunk connection with Asterisk2 and Asterisk3
3. Caller register SIP phone with Asterisk1
     Caller extension = 8002
4. Asterisk2 makes a blind transfer to Kamailio. (Call to 8009  then
transfer to ARI APP)
     exten = 8009,1,Transfer(SIP/3802@<kamailio public IP>)
5. ARI app extension is 3802


My problem is that Kamailio LB only works when I try to connect
with Asterisk1 and Asterisk2 or  Asterisk1 and Asterisk3. If I have two
Asterisks in dispatcher.list, it doesn't work and it appears *SIP/2.0 401
Unauthorized* in sip packets capture log.

Kamailio version: 5.5.2
Kamailio.cfg

modparam("dispatcher", "list_file", "/etc/kamailio/dispatcher.list")
modparam("dispatcher", "flags", 3)
modparam("dispatcher", "xavp_dst", "_dsdst_")
modparam("dispatcher", "xavp_ctx", "_dsctx_")

# Dispatch requests
route[DISPATCH] {
        # round robin dispatching on gateways group '1'
        if(!ds_select_dst("1", "4")) {
                send_reply("404", "No destination");
                exit;
        }
        xdbg("--- SCRIPT: going to <$ru> via <$du> (attrs:
$xavp(_dsdst_=>attrs))\n");
        t_on_failure("RTF_DISPATCH");
        route(RELAY);
        exit;
}

# Try next destionations in failure route
failure_route[RTF_DISPATCH] {
        if (t_is_canceled()) {
                exit;
        }
        # next DST - only for 500 or local timeout
        if (t_check_status("500")
                        or (t_branch_timeout() and !t_branch_replied())) {
                if(ds_next_dst()) {
                        xdbg("--- SCRIPT: retrying to <$ru> via <$du>
(attrs: $xavp(_dsdst_=>attrs))\n");
                        t_on_failure("RTF_DISPATCH");
                        route(RELAY);
                        exit;
                }
        }
}

dispatcher.list
# setid(int) destination(sip uri) flags(int,opt) priority(int,opt)
attrs(str,opt)
1 sip:10.148.0.31:5123
1 sip:10.148.0.44:5123

Thanks,
Warawich
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