As an example:
If you have one ICAP server (ICAP max connections max 4000), then if you use one client (Proxy) for sending the traffic then the max supported should be 4000. If you share the ICAP server among many devices you need to divide it by the number of devices as ex. ICAP server (4000) / 2x Proxies = 2000 ICAP connections per device.
ICAP MAXIMUM CONNECTIONS FOR CONTENT ANALYSIS (CAS) INSTANCE
If you’re using our Content Analysis as an ICAP server, there is a table that describes the number of ICAP concurrent connections supported and recommended setting for proxy (table shows settings 1CAS per 1Proxy) - Recommended ICAP connections on ProxySG and Maximum ICAP connections supported on Content Analysis models.
AUTOMATIC CONFIGURATION FOR ICAP SERVER (SENSE SETTINGS)
When setting a new ICAP server on the Proxy (Proxy>Configuration>Content Analysis>ICAP) you have an option at the bottom of the configuration screen called “Sense settings” that negotiates the preferred settings with the ICAP server automatically.
ICAP SCAN LOAD-BALANCING BETWEEN SEVERAL ICAP SERVERS
To load-balance multiple ICAP servers configured within same product (CAS, Fireeye, Symantec DLP) it is recommended to create ICAP service group for same type of ICAP servers. Service group will help to load-balance the ICAP requests among same type of the ICAP servers:
When Proxy group service is used in the Web Content Layer rule, Proxy chooses one of the ICAP servers from the group based on the weight set or by using an intelligent load balancing algorithm which chooses the best server from the list by checking the loads and availability on ICAP servers from the list.
When deciding which service in the service group to send a scanning request, the intelligent load balancing algorithm takes into consideration the following factors:
If you’d like to combine two different ICAP services (Fireeye, CAS or DLP scanner) you should create two separate rules specifying which service group of devices should be used for scanning. See more https://knowledge.broadcom.com/external/article/263508