Post Processing Feature - Cisco ASR 5000 series Product Overview

▀ Enhanced Services in ECS

Post Processing Feature

The Post Processing feature enables processing of packets even if the rule matching for them has been disabled. This
enables all the IP/TCP packets including TCP handshaking to be accounted and charged for in the same bucket as the
application flow. For example, delay-charged packets for IP Readdressing and Next-hop features.
Readdressing of delay-charged initial hand-shaking packets.
Sending the delay-charged initial packets to the correct next-hop address.
DCCA: Taking appropriate action on retransmitted packets in case the quota was exhausted for the previous
packet and a redirect request was sent.
Content ID based ruledefs: On rule match, if content ID based ruledef and charging action are present, the rule is
matched, and the new charging action will decide the action
A ruledef can be configured as a post-processing rule in the ruledef itself using rule-application of the ruledef. A rule
can be charging, routing, or a post-processing rule. If the same ruledef is required to be a charging rule in one rulebase
and a post-processing rule in another one, then two separate identical ruledefs must be defined.
How the Post-processing Feature Works
The following steps describe how the Post-processing feature works:
Step 1
Charging rule-matching is done on packets and the associated charging-action is obtained.
Step 2
Using this charging-action the disposition-action is obtained.
Step 3
If the disposition action is to either buffer or discard the packets, or if it is set by the ACF, or if there are no post-
processing rules, the packets are not post processed. The disposition action is applied directly on the packets. Only if
none of the above conditions is true, post processing is initiated.
Step 4 Post-processing rules are matched and the associated charging-action and then the disposition-action obtained through
control-charge.
Step 5
If both match-rule and control-charge for post processing succeed, the disposition-action obtained from post-processing
is applied. Otherwise, the disposition-action obtained from charging rule-matching is used.
If no disposition action is obtained by matching post-processing rules, the one obtained by matching
charging-rules will be applied.
Irrespective of whether post processing is required or not, even if a single post-processing rule is configured
in the rulebase, post processing will be done.
The following points should be considered while configuring post-processing rules for next-hop/readdressing.
▄ Cisco ASR 5000 Series Product Overview
DCCA with buffering enabled: Match CCA rules, charging-action will decide action—terminate
flow/redirect
DCCA with buffering disabled: Match post-processing rules, and take action
The rules will be L3/L4 based.
They should be configured in post-processing rules' charging actions.
Enhanced Charging Service Overview
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