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1. SIP traffic from Skype for Bussiness Front-End and\or Edge servers (depending on the configuration) is being inspected if a cached policy is already applied to it.

2. Check if there is a preexisting calculation

   the traffic is being redirected to the Maintenance service on the Admin Portal If there is no pre-existing cache.

   The Maintenance Service calculates and caches the rules for future calculations and returns the policy back to the SIP Filter

   pre-existing calculation in the database cache.

   1. If not, the SIP Filter itself will calculate the policy and store it in the database cache.

   2. If the calculation requires access to internal resources (UCMA or LDAP) and the SIP Filter is running on the Edge, the SIP Filter will query the Access Portal API to get the policies.

3. SIP filter cache the policy locally and enforce the calculated policy.

4. The maintenance service keeps refreshing the database cache to verify validity.

Examples:

1. In case the communication is allowed and precalculatedpre-calculated:

   1. Alice@external.com sends a message "Hello!" to bob@internal.com

   2. This reaches the Edge/Front End, Edge/Front End forwards this to the SIP Filter

   3. Sip SIP Filter checks in the Policy Cache and sees this already has been calculated by the Maintenance serviceSip .

   4. SIP Filter returns the found policy cache, which allows the traffic to bob.

2. In case the communication is blocked and not precalculatedpre-calculated:

   1. Eve@external.com sends a message "Hey!" to Bob@internal.com

   2. This reaches the Edge/Front End, Edge/Front End forwards this to the SIP Filter

   3. SIP Filter checks in the policy cache and doesn't find add, thus calculates and adds the calculation result as a record in the Policy policy cache

   4. SIP Filter returns the calculated policy, which blocks the traffic to bob.

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Learning Mode

This mode applies calculation and caching for the configured policies however only the Default is designed to build a large cache in the database. While in learning more, only default policies are being enforced by the SIP filter.

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This is due to the introduced load of calculating policies without preexisting pre-existing cache that can hinder the normal Skype for Bussiness operation and generate instabilities.

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1.  Alice@external.com sends a message "Hello!" to Bob@internal.com

2. This reached the Edge/Front End, Edge/Front End forwards this to the SIP Filter

3. Sip SIP Filter checks & returns the corresponding Default policy for this Traffic (Default external).

4. Sip SIP Filter inputs a new record to the Ethical wall Policy Cache

5. Maintenace service checks the new Policy cache entry

6. Maintenance .

7. The maintenance service finds the corresponding policy for this cacherecord.

8. Maintenance The maintenance service updates this cache in the database.

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