Next-Hop Address Configuration - Cisco ASR 5000 Series Administration Manual

▀ Enhanced Features and Functionality
Table 3. URL HTTP Request Re-addressing
Step Description
1— UE sets up a TCP connection with the Origin Server (OS) by sending SYN. The TCP three-way handshake takes place
3 between UE and the Origin Server.
4 UE sends a HTTP request to the OS which passes through the ASR5x00 L7 DPI rule-matching. The URL of the request
contains a known token, domain name, or a token configured at ASR5x00 (in a ruledef).
5— ASR5x00 using L7 DPI recognizes that the request is for New Server. ASR5x00 breaks/closes the existing TCP connection
8 with OS and establishes a new connection with the New Server. TCP proxy is used to maintain TCP connection between
UE and ASR5x00.
9 ASR5x00 sends the HTTP Request destined for Origin Server to New Server.
10 New Server sends back the content in HTTP Response.
11 ASR5x00 proxies the content back to the UE.
12 UE closes the TCP connection.
13 ASR5x00 closes the connection with the New Server.

Next-hop Address Configuration

ECS supports the ability to set the next-hop default gateway IP address as a charging action associated with any ruledef
in a rulebase. This functionality provides more flexibility for service based routing allowing the next-hop default
gateway to be set after initial ACL processing. This removes need for AAA to send the next-hop default gateway IP
address for CC opted in subscribers.
In 15.0 and later releases, ECS behaves such that rule matching is not done for partial HTTP request if HTTP analysis is
enabled.
Assume ECS has received partial HTTP GET packet where URL is not complete, and there are a few URL based rules
configured. At this point of time, ECS will not be in a position to match proper rule as complete URL information is not
available. When packet where request is completed, is received by ECS, proper rule matching is possible. Earlier partial
packets and bytes of this request will be charged accordingly.
Also, this does not apply to post-processing rules. Post-processing rules are matched for all the packets, irrespective of
the packet is partial or not. If the customer wants to configure actions like next-hop forwarding or ip-readdressing, then
that can be configured in post-processing rules.
In releases prior to 15.0, partial packets do not go for post processing rule match. Whereas in 15.0 and later releases, the
partial packets go for required rule match. This behavior change is introduced to obtain the correct statistics about the
packets.
How it works:
Step 1
The next-hop address is configured in the charging action.
Step 2
Uplink packet sent to ECS is sent for analysis.
Step 3
When the packet matches a rule and the appropriate charging action is applied, the next-hop address is picked from the
charging action and is copied to the packet before sending the packet to Session Manager.
▄ Cisco ASR 5x00 Enhanced Charging Services Administration Guide
44
Enhanced Charging Service Overview