Cisco Cisco Unified SIP Proxy Guia De Resolução De Problemas

    in−network Net−CUCM

    method INVITE

    end sequence

  sequence 2

   in−network Net−PSTN

   local−port 5060

   end sequence

end trigger condition

This section describes the routing lookup policy for the CUSP call processing flow. 

Each routing policy is expressed as a sequence of steps and each is specified in order to perform a
lookup in a table.

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CUSP executes each step in order:

Each step has a selectable key.

♦ 

If the step produces a route, that route is used.

♦ 

If the step results in a "no−match," the next step is attempted.

♦ 

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An SIP request can be routed to a single destination or to a Route Group (RG).

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The policy has Multi−layer Route Advance within a RG, and has configurable failover SIP response
codes.

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Policy−based request rejection is incorporated (4xx responses and above).

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Nested policies are allowed.

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Table−based routing is used, which has these properties:

It supports a large number of routes in a table (10,000+).

♦ 

Routes in a table are populated via CLI or a route file.

♦ 

Lookup keys are used, such as calling and called party number, carrier codes, and location
routing numbers.

♦ 

Flexible rule matching is used, such as "longest prefix matching."

♦ 

• 

This section describes the CUSP call processing flow normalization policy. 

SIP headers are normalized based on a configured policy.

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Normalization involves the addition, modification, and removal of SIP headers.

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It is applicable to both SIP requests and responses.

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It is used in order to solve incompatibilities or interoperation issues between different SIP servers.

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It can be performed before or after routing logic is executed (Pre−Normalization and
Post−Normalization).

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Normalization logic:

Normalization Policy − Defines what changes must be made to the SIP message.

♦ 

Normalization Triggers − Define how a normalization policy is chosen.

♦ 

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The policy consists of steps, and each step specifies a single change to the SIP message. For example:

Number normalization

♦ 

TEL/SIP conversions

♦ 

Domain conversions

♦ 

Regular−expression processing

♦ 

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Here is a flow chart that shows the process: