Live mode
This is the regular operation mode of the Ethical wall and it goes as follow:
SIP traffic from Skype for Bussiness Front-End and\or Edge servers is being inspected if a cached policy is already applied to it.
Check if there is a pre-existing calculation in the database cache.
If not, the SIP Filter itself will calculate the policy and store it in the database cache.
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.
SIP filter cache the policy locally and enforce the calculated policy.
The maintenance service keeps refreshing the database cache to verify validity.
Examples:
In case the communication is allowed and pre-calculated:
Alice@external.com sends a message "Hello!" to bob@internal.com
This reaches the Edge/Front End, Edge/Front End forwards this to the SIP Filter
SIP Filter checks in the Policy Cache and sees this already has been calculated.
SIP Filter returns the found policy cache, which allows the traffic to bob.
In case the communication is blocked and not pre-calculated:
Eve@external.com sends a message "Hey!" to Bob@internal.com
This reaches the Edge/Front End, Edge/Front End forwards this to the SIP Filter
SIP Filter checks in the policy cache and doesn't find, thus calculates and adds the calculation result as a record in the policy cache
SIP Filter returns the calculated policy, which blocks the traffic to bob.
Learning Mode
This mode is designed to build a large cache in the database. While in learning more, only default policies are being enforced by the SIP filter.
It is recommended to maintain this mode during a fresh deployment in order to establish a comprehensive enough cache.
This is due to the introduced load of calculating policies without pre-existing cache that can hinder the normal Skype for Bussiness operation and generate instabilities.
Example of the operation during Learning Mode:
Alice@external.com sends a message "Hello!" to Bob@internal.com
This reached the Edge/Front End, Edge/Front End forwards this to the SIP Filter
SIP Filter checks & returns the corresponding Default policy for this Traffic (Default external).
SIP Filter inputs a new record to the Ethical wall Policy Cache.
The maintenance service finds the corresponding policy for this record.
The maintenance service updates this cache in the database.