Cisco Cisco Packet Data Gateway (PDG)
ECS Changes in Release 17
▀ ECS Enhancements for 17.1
▄ Release Change Reference, StarOS Release 17
132
CSCuo68909 - TCP flows modification (RFC 1122, Section 4.2.2.13)
Applicable Products: eHRPD, GGSN, HA, HSGW, PDSN, P-GW, S-GW
Feature Changes
Modification of TCP Flows
In some scenarios, UE initiates a new TCP connection request (SYN) reusing the existing source port number, received
within the 2MSL time frame of the exisiting flow. The data flow pertaining to this old connection gets deleted after
2MSL timeout, if configured and till then the new TCP connection traffic goes on the same data flow. The TCP analyzer
is not able to reopen existing TCP flow, in response to UE's new behavior.
within the 2MSL time frame of the exisiting flow. The data flow pertaining to this old connection gets deleted after
2MSL timeout, if configured and till then the new TCP connection traffic goes on the same data flow. The TCP analyzer
is not able to reopen existing TCP flow, in response to UE's new behavior.
The TCP analyzer has been enhanced to support the optional behavoir in RFC 1122, section 4.2.2.13. ECSv2 now clears
the old data flow before 2msl timeout and creates a new data flow, for UE's new connection using same port number. It
will also generate and send last ack packet if not already sent. New CLI command has also been introduced to control
this feature at rulebase level. You can enable or diable this feature using the CLI command. The stats counters have also
been modified to indicate the number of port reuse flows.
the old data flow before 2msl timeout and creates a new data flow, for UE's new connection using same port number. It
will also generate and send last ack packet if not already sent. New CLI command has also been introduced to control
this feature at rulebase level. You can enable or diable this feature using the CLI command. The stats counters have also
been modified to indicate the number of port reuse flows.
Command Changes
tcp 2msl-timeout
A new keyword
port-reuse
has been added to the command
tcp 2msl-timeout
at rulebase level to support the
source port reuse.
configure
active-charging service service_name
rulebase rulebase_name
[ default | no ] tcp 2msl-timeout time_in_sec [ port-reuse ]
end
Notes:
port-reuse: Allows the source port reuse to reopen the tcp flow in 2msl timeout.
When
port-reuse
keyword is configured along with
tcp 2msl-timeout
, reuse of the same source port
number within 2msl timeout of previous flow, is permitted (supported in code).
When
port-reuse
keyword is not configured along with the
tcp 2msl-timeout
, reuse of the same source
port number within 2msl timeout of the previous flow, is not supported and such a packet will be dropped.
Performance Indicator Changes
show active-charging rulebase
This command has been modified to include the following in the output:
Port Reuse: [Yes/No]