Cisco ASR 5000 Series Administration Manual page 41

Enhanced Charging Service Overview
Step Description
No.
5 The Policy Manager and AAA generate and send an Access Accept message including all policy and other attributes to
establish the session to ECS.
The Policy Manager and/or AAA include following attributes in the Access Accept message:

Filter ID or Access Control List Name: Applied to subscriber session. It typically contains the name of the
Content Service Steering (CSS) ACL. The CSS ACL establishes the particular service treatments such as Content
Filtering, ECS, Stateful Firewall, VPN, etc. to apply to a subscriber session, and the service order sequence to use
in the inbound or outbound directions. Real-time or delay sensitive flows are directly transmitted to the Internet
with no further processing required. In this case, no CSS ACL or Filter ID is included in the Access Response.

SN1-Rulebase Name: This custom attribute contains information such as consumer, business name,
child/adult/teen, etc. The rulebase name identifies the particular rule definitions to apply. Rulebase definitions are
used in ECS as the basis for deriving charging actions such as prepaid/postpaid volume/duration/destination
billing and charging data files (EDRs/UDRs). Rulebase configuration is defined in the ACS Configuration Mode
and can be applied to individual subscribers, domains, or on per-context basis.
6 ECS creates a new session for UE, and sends the rulebase to ACS subsystem if required.
7 ECS sends Accounting-Start messages to the AAA server.
8 The AAA server sends Accounting-Start response message to ECS.
9 ECS establishes data flow with UE.
10 UE requests for data with URL name (DNS query).
11 ECS analyzes the query-name from the subscriber's DNS query, and if it matches the entry in the "DNS URLs to be
snooped" list (created when ip server-domain-name rules were defined in rulebase), it marks this request for its response to
be snooped.
12 DNS query is sent to the Internet.
13 DNS response is received from the Internet.
14 Based on the various answer records in the response the IP addresses are snooped and included in the "list of learnt IP
addresses".
15 DNS response is sent to the UE.
16 Actual URL request comes from the UE.
17 Looking at the server-ip-address of the packet, rule matching will be done based on the "list of learnt IP addresses" and the
rules already configured. An action is taken based on the ruledef matched and the charging action configured.
18 If the packet is to be forwarded, it is forwarded to the Internet.
19 A response is received from the Internet.
20 The response is sent to the UE.
21 UE requests for session termination.
22 System sends Accounting-Stop Request to AAA server.
23 AAA server stops accounting for subscriber and sends Accounting-Stop-Response to the system.
Cisco ASR 5x00 Enhanced Charging Services Administration Guide ▄
Enhanced Features and Functionality ▀
41