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Scenario

The 

Background Information

• The Integrated Access Device (IAD) is registered with an Application Server (AS).
• The AS is protected by an

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  . The IAD discovers the

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  via DNS resolution and the

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  discovers the AS by pre-configured routing or external DB dip (e.g. ENUM).
• Once registered, the IAD communicates with a specific

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  , and the

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  forwards requests to the specific AS (address was stored during registration).
• For calls terminating to the IAD, the IADs register their AORs.
• IAD has been registered by two paths and can afford for one path to fail and still receive service on the other, when it supports outbound. In a normal scenario where the IAD registers through one path and is unable to refresh the register, it moves on to an alternate

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  from DNS.

Description

Figure 1: Basic Service Availability- DNS

1. The IAD is configured with a FQDN identifying a set of

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   s.
2. The DNS supplies multiple

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   IP addresses (local, remote or a combination of both).
3. Basic geo-redundancy and load balancing between the

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   s are enabled. With geo-redundancy, if an

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   fails, the IAD re-registers through a different path.