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METHOD FOR DYNAMIC OPTIMIZED FAILOVER FOR DNS-BASED SIP DESTINATIONS

IP.com Disclosure Number: IPCOM000243573D
Publication Date: 2015-Oct-01
Document File: 6 page(s) / 405K

Publishing Venue

The IP.com Prior Art Database

Related People

Paul Giralt: AUTHOR

Abstract

An approach is presented herein to ensure minimal end-user impact when placing calls in a Domain Name System (DNS)-based dynamic Session Initiation Protocol (SIP) peering environment. An edge gateway dynamically monitors remote destinations when a failure occurs and ensures the destination is not used until the edge gateway detects it has returned to service. This approach involves dynamically building a monitoring table as opposed to always monitoring statically-configured destinations. The advantages include much-improved failover times in a DNS-based peering.

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METHOD FOR DYNAMIC OPTIMIZED FAILOVER FOR DNS-BASED SIP DESTINATIONS

AUTHORS:

Paul Giralt

CISCO SYSTEMS, INC.

ABSTRACT

    An approach is presented herein to ensure minimal end-user impact when placing calls in a Domain Name System (DNS)-based dynamic Session Initiation Protocol (SIP) peering environment. An edge gateway dynamically monitors remote destinations when a failure occurs and ensures the destination is not used until the edge gateway detects it has returned to service. This approach involves dynamically building a monitoring table as opposed to always monitoring statically-configured destinations. The advantages include much-improved failover times in a DNS-based peering.

DETAILED DESCRIPTION

     Business-to-Business Session Initiation Protocol (SIP) peering through SIP Domain Name System (DNS) Service Record Value (SRV) or A records allows users to dynamically discover SIP services and place calls without any pre-configured peering. These records can include a set of Internet Protocol (IP) destinations for redundancy. However, the ability to connect a call when one of the advertised entries is unavailable leads to undesirable post-dial delay for every call to the destination experiencing the outage.

    Direct peering connections to a known destination(s) can leverage keep-alive mechanisms such as SIP OPTIONS pings to maintain availability information on the configured destinations. However, it is not possible to send OPTIONS pings to every possible destination on the Internet.

    In a business-to-business SIP environment leveraging DNS records to discover other businesses, a customer places a call to a Uniform Resource Identifier (URI) such as alice@biloxi.com. The edge gateway performs a variety of DNS requests based on the

Copyright 2015 Cisco Systems, Inc.
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domain - biloxi.com - depending on the configuration of the edge gateway. For example, it could perform one or more of these requests:

DNS A Record for biloxi.com DNS SRV for _sip._tcp.biloxi.com DNS SRV for _sips._tcp.biloxi.com DNS SRV for _sip._udp.biloxi.com

    After performing one or more DNS queries, the edge gateway leverages the priorities specified in the SRV and any other internal prioritization logic to form the list of destinations to try in order to reach the biloxi.com domain. See FIG. 1 below. For example, _sips._tcp.biloxi.com might return 4 A records with different priorities (e.g. Priority 10, 20, 30, and 40). The edge gateway will then perform a DNS A record lookup to find the IP addresses of the 4 destinations.

FIG. 1

    In this case, because the transport is Transport Control Protocol (TCP), the gateway will attempt a TCP socket connection to the highest priority destination (if one does not already exist when SIP connection reuse is being used) and, if successful, send a Copyright 2015 Cisco Systems, Inc.

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SIP INVITE. If the TCP socket fails to connect or there is no response to the INVITE in a given amount of time, the edge gateway...