Cisco ASR 5000 Series Administration Manual page 15

Enhanced Charging Service Overview
CSS uses Access Control Lists (ACLs) to redirect selective subscriber traffic flows. ACLs control the flow of packets
into and out of the system. ACLs consist of "rules" (ACL rules) or filters that control the action taken on packets
matching the filter criteria.
ACLs are configurable on a per-context basis and applies to a subscriber through either a subscriber profile (for PDSN)
or an APN profile (for GGSN) in the destination context.
Important:
Administration Guide. For more information on ACLs, refer to the IP Access Control Lists chapter of the System
Administration Guide.
Protocol Analyzer
The Protocol Analyzer is the software stack responsible for analyzing the individual protocol fields and states during
packet inspection.
The Protocol Analyzer performs two types of packet inspection:
 Shallow Packet Inspection—Inspection of the layer 3 (IP header) and layer 4 (for example, UDP or TCP
header) information.
 Deep Packet Inspection—Inspection of layer 7 and 7+ information. DPI functionality includes:
 Detection of Uniform Resource Identifier (URI) information at level 7 (for example, HTTP, WTP, and
 Identification of true destination in the case of terminating proxies, where shallow packet inspection
 De-encapsulation of upper layer protocol headers, such as MMS-over-WTP, WSP-over-UDP, and IP-
 Verification that traffic actually conforms to the protocol the layer 4 port number suggests
The Protocol Analyzer performs a stateful packet inspection of complex protocols, such as FTP, RTSP, and SIP, which
dynamically open ports for the data path, so the payload can be classified according to content.
The Protocol Analyzer is also capable of determining which layer 3 packets belong (either directly or indirectly) to a
trigger condition (for example, URL). In cases where the trigger condition cannot be uniquely defined at layers 3 and 4,
then the trigger condition must be defined at layer 7 (that is, a specific URL must be matched).
Protocol Analyzer Software Stack
Every packet that enters the ECS subsystem must first go through the Protocol Analyzer software stack, which
comprises of individual protocol analyzers for each of the supported protocols.
For more information on CSS, refer to the Content Service Steering chapter of the System
RTSP URLs)
would only reveal the destination IP address/port number of a terminating proxy
over GPRS
Cisco ASR 5x00 Enhanced Charging Services Administration Guide ▄
Basic Features and Functionality ▀
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