Detecting Reuse of TCP Ports

Feature Summary and Revision History

Summary Data

Applicable Product(s) or Functional Area

P-GW

Applicable Platform(s)

  • ASR 5500

  • VPC-DI

  • VPC-SI

Feature Default

Disabled - Configuration Required

Related Changes in This Release

Not Applicable

Related Documentation

  • Command Line Interface Reference

Revision History

Revision Details

Release

P-GW supports TCP port reuse through CLI configuration.

21.28.m15

Feature Changes

Previous Behavior: In P-GW, the non-detection of TCP source port reuse lead to Out-of-order (OOO) packet and retransmission packet which inturn resulted in bypassing the charging module and traffic allowed to the server.

New Behavior: In P-GW, the tcp-detect-port-reuse CLI is introduced to control the specific flow matching the charging action to detect the source port reuse by TCP SYN packet. The tcp-detect-port-reuse CLI also clears the flow in which port is reused and creates new credentials.

Command Changes

This command allows you to detect the source port reuse by TCP packets. When a packet matches to the rule that includes charging action that is enabled with tcp-detect-port-reuse, TCP SYN packet checks for the port reuse. When port reuse is detected the respective flow is cleared and a new flow is created with the new credentials. 


configure 
   context context-name 
      active-charging service service_name 
         charging-action charging_action_name 
           [ no ] tcp-detect-port-reuse

NOTES

  • tcp-detect-port-reuse : Detects the source port reuse by TCP packets. By default this CLI is disabled.

  • no : Removes the tcp-detect-port-reuse configuration from the charging action.

Monitoring and Troubleshooting

This section provides information about the CLI commands available to monitor and/or troubleshoot TCP port reuse feature.

Show Command(s) and/or Outputs

show active-charging rulebase statistics name

This command displays the following specific flow information matching the charging action to detect the source port reuse. Following is a sample output: 


show active-charging rulebase statistics name RB_IITC_DAIMLER
      Detect TCP Port Reuse and Flow Cleared:                1
[local]laas-setup# show active-charging charging-action statistics name CA_RG1_NORMAL
 Service Name: ecs-svc1
  Charging Action Name: CA_RG1_NORMAL
    Uplink Pkts Retrans:             32   Downlink Pkts Retrans:             7
    Uplink Bytes Retrans:         13567   Downlink Bytes Retrans:         3558
    Flows Readdressed:                0   PP Flows Readdressed:              0
    Bytes Charged Yet Packet Dropped:                 0
    Predef-Rules Deactivated:         0
    Outer IP header dscp marked Pkts:                0
Detect TCP Port Reuse and Flow Cleared:                 1