3 May
2005
3 May
'05
11:25 a.m.
Juha Heinanen wrote:
in summary: a load balancing solution that at the same
time is redundant
is not possible using the participating sers alone. some intelligent
front end help is needed and i'm not convinced yet that even that could
be done.
What about this (maybe a special case):
I was just thinking about STUN, and AFAIK this relies on a NAT device
not matching the source IP of a datagram, so the client opens a NAT
binding to an STUN server to determine an external IP/port pair which is
filled in the Contact header. The Proxy then can also send SIP requests
to this external IP/port which is forwarded to the client by the NAT
device. Is this basically correct?
If so, it theoretically should work with transparent NAT handling on two
SERs too, if both SERs know the external IP/port of UAC-1.
I also think I know now why it didn't work for me: SER-1 got the request
from UAC-1 and stored the contact IP and the received IP in the location
table. SER-2 got the replicated register but stored SER-1's IP as
received IP:
On SER-1 (2.2.2.2 is the external IP of UAC-1, 3.3.3.3 is the IP of SER-1):
mysql root@ser> select * from location where username='018904449'\G
*************************** 1. row ***************************
username: 018904449
domain:
contact: sip:018904449@192.168.34.187:50600
received: sip:2.2.2.2:50600
expires: 2005-05-03 10:19:17
q: -1.00
callid: 1338383826(a)192.168.34.187
cseq: 2
last_modified: 20050503101557
replicate: NULL
state: NULL
flags: 1
user_agent: Linphone-1.0.1/eXosip
1 row in set (0.00 sec)
And on SER-2:
mysql root@ser> select * from location where username='018904449'\G
*************************** 1. row ***************************
username: 018904449
domain:
contact: sip:018904449@192.168.34.187:50600
received: sip:3.3.3.3:46236;transport=TCP
expires: 2005-05-03 10:19:15
q: -1.00
callid: 1338383826(a)192.168.34.187
cseq: 2
last_modified: 20050503101555
replicate: NULL
state: NULL
flags: 1
user_agent: Linphone-1.0.1/eXosip
1 row in set (0.00 sec)
My config basically looks like this (NAT-flag is "2"):
if (method=="REGISTER")
{
if(is not from Peer-SER-IP)
{
if(!search("^Contact: \*") && client_nat_test("7"))
{
setflag(2);
fix_nated_register();
force_rport();
append_hf("Natted: yes\r\n");
}
if(!www_authorize("<auth domain>", "subscriber"))
{
www_challenge("<auth domain>", "0");
break;
}
if(!check_to())
{
sl_send_reply("403", "Use To=id next time");
break;
}
consume_credentials();
if(!save("location"))
{
sl_reply_error();
break;
}
forward_tcp("<Peer-SER-IP>", 5060);
}
else
{
if(is_present_hf("Natted"))
{
setflag(2);
fix_nated_register();
force_rport();
}
save_noreply("location");
}
break;
}
I'll investigate the problem and report back here. Or do I miss
something important?
Andy