You can use the Policy Enforcement Manager™ to create service chains to route traffic to one or more value-added services on the way to its final destination. The service chains define the path and order that you want traffic to take. There are several value-added services involved and after each endpoint the traffic comes back to the BIG-IP system. An endpoint specifies each place you want to send the traffic, so the service chain is essentially between the value-added services endpoints for traffic to stop at on its way to the server it is headed to. For example, you can forward traffic sequentially for virus scanning, parental control, and caching.
You set up service chains by creating an enforcement policy that defines the traffic that you want to route to the service chain. Rules in the enforcement policy specify conditions that the traffic must match, and actions for what to do with that traffic. One of the actions you can take is to send the traffic to a service chain.
While a static service chain defines fixed value-added services, a dynamic service chain provides service chain action that can dynamically change depending on the flow of parameters and you can attach a steering policy that can override the decision of the next session. You can use dynamic service chain to insert or name header and steer different service. Internet Content Adaptation Protocol (ICAP) is one of the services possible to use in a service chain. Dynamic service chain makes the service chain intelligent and flexible by providing the following support:
You can create listeners to set up virtual servers and associate enforcement policies with the traffic that is sent to them. The system also creates a Policy Enforcement profile that specifies the enforcement policy that the system uses for the service chain.
You can configure the Internet Content Adaptation Protocol (ICAP) profile, request adaptation profile, and response adaptation profile for using the dynamic service chain feature in Policy Enforcement Manager™.
The internal virtual server references the pool of content adaptation servers. The internal virtual server also references an ICAP profile, which includes specific instructions for how the BIG-IP® system should modify each request or response. Once the request and response adapt profiles have been created, you can attach the profiles to the HTTP virtual server. The adapt profiles use multiple internal virtual servers for various content types.
The HTTP listener must have adapt profile set. The adapt profiles need to be configured as disabled and are enabled by PEM based on the policy action applied.
The service chain endpoints that have steering policy attached, define the service chain. The dynamic service chain follows these processing strategies:
The steering policy changes the service chain in many ways:
You create this ICAP profile when you want to use an ICAP server to wrap an HTTP request in an ICAP message before the BIG-IP® system sends the request to a pool of web servers. The profile specifies the HTTP request-header values that the ICAP server uses for the ICAP message.
When you configure a new forwarding endpoint (Address Translation and Port Translation as Disabled.), set
|Route to Network||The traffic flow is forwarded to the default destination.|
|Forwarding to Endpoint||The flow is steered to a different destination and you can select one of the endpoints.|
|Forward to ICAP virtual Server||The flow is forwarded to the ICAP virtual server.|