Use DNS procedures to locate Session Initiation Protocol (SIP) servers

Use DNS procedures to locate SIP servers

The Session Initiation Protocol (SIP) can use Domain Name Server (DNS) procedures for a client to resolve a SIP Uniform Resource Identifier (URI).

WebSphere Application Server provides support for the RFC 3263 standard. This allows a SIP URI to be resolved through DNS into the IP address, port, and transport protocol of the next hop to contact.
SIP does not support use of DNS procedures for a server to send a response to a back-up client if the primary client fails.
Complete these steps to configure WebSphere Application Server to support the RFC 3263 standard.

Start WebSphere Application Server.

From the console, enable...
Servers | Application servers | serverName | General Properties | Enable locating SIP servers using DNS NAPTR records

Fill in the Primary DNS server name and Secondary DNS server name fields.

Click Apply to save the changes.

Restart WebSphere Application Server.

What to do next

We must configure the DNS server in order for RFC 3263 support to work for the SIP container. The following example is a BIND db file for configuring RFC 3263 support on a DNS server.
; Copyright (C) 2004  Internet Systems Consortium, Inc. ("ISC")
; Copyright (C) 2001  Internet Software Consortium.
;
; Permission to use, copy, modify, and distribute this software for any ; purpose with or without fee is hereby granted, provided that the above
; copyright notice and this permission notice appear in all copies.
;
; THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
; REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
; AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT, ; INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
; LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
; OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR ; PERFORMANCE OF THIS SOFTWARE.
 ; $Id: include.db,v 1.2.206.1 2004/03/06 10:22:13 marka Exp $
 ; Test $INCLUDE current domain name and origin semantics
 example.com. 43200 IN SOA ns.example.com. email.example.com. ( 2003032001 10800 3600 604800 86400 )
;
example.com.         43200 IN NS      ns.example.com.
;
ns.example.com.      43200 IN A       10.0.0.20
sipserver1.example.com.  43200 IN A       10.0.0.21
sipserver2.example.com.  43200 IN A       10.0.0.22
sipserver3.example.com.  43200 IN A       10.0.0.23
;
router.example.com.    43200  IN CNAME sipserver3
;
sipserver1.example.com.  43200 IN AAAA    fec0:0:0:0:0:0:0:abcd
sipserver2.example.com.  43200 IN AAAA    fec0:0:0:0:0:0:0:abba
;
_sip._udp.example.com.   43200 IN SRV 2 0 5060  sipserver1.example.com.
_sip._udp.example.com.   43200 IN SRV 2 0 5060  sipserver2.example.com.
_sip._tcp.example.com.   43200 IN SRV 1 4 5060  sipserver1.example.com.
_sip._tcp.example.com.   43200 IN SRV 1 2 5060  sipserver2.example.com.
_sips._tcp.example.com.  43200 IN SRV 0 1 5061  sipserver1.example.com.
_sips._tcp.example.com.  43200 IN SRV 0 0 5061  sipserver2.example.com.
;
example.com. 43200 IN NAPTR 0 0 "s" "SIPS+D2T" "" _sips._tcp.example.com.
example.com. 43200 IN NAPTR 1 0 "s" "SIP+D2T"  "" _sip._tcp.example.com.
example.com. 43200 IN NAPTR 2 0 "s" "SIP+D2U"  "" _sip._udp.example.com.
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