Citrix ADC

Monitor the free ports available on a Citrix ADC appliance for a new back-end connection

For communication with the physical servers or other peer devices, the Citrix ADC appliance uses a Citrix owned IP address as the source IP address. The Citrix ADC appliance maintains a pool of its IP addresses, and dynamically selects an IP address while connecting with a server. Depending on the subnet in which the physical server is placed, the appliance decides which IP address to use. This address pool is used for sending traffic and monitor probes.

You can display the total number of free ports available on the Citrix ADC owned IP addresses for a new back-end connection. This information helps you in deciding the need for more Citrix owned IP addresses if the free ports available are nearing exhaustion.

You can provide the following information for the Citrix ADC appliance to calculate the total number of free ports available for a new back-end connection:

  • Citrix owned IP address (optional)
  • Destination IP address
  • Destination port
  • TCP or non-TCP protocol

When you specify all the information except specifying a Citrix owned IP address:

  • The Citrix ADC appliance performs a route lookup for finding all the Citrix owned IP addresses that can connect to the destination IP address. The appliance then finds and displays the total number of free ports available on these Citrix owned IP addresses for the specified new back-end connection.

    Note:

    The Citrix ADC appliance does not perform ECMP lookup, or LLB lookup path, or PBR lookup path for finding the Citrix owned IP addresses that can connect to the destination IP address.

When you specify all the information including specifying a Citrix owned IP address:

  • The Citrix ADC appliance displays the number of free ports available on the specified IP address for the specified new back-end connection.

Before you begin

Before you display the total number of free ports available for a new back-end connection, make note of the following points:

  • The Citrix ADC appliance does not perform ECMP lookup, or LLB lookup path, or PBR lookup path for finding the Citrix owned IP addresses that can connect to the destination IP address.

  • The Citrix ADC appliance does not support displaying free ports available on a link local IP address.

Steps for displaying the number of free ports available on a Citrix ADC appliance for a new back-end connection

To display the total number of free ports available on a Citrix ADC appliance for a new back-end connection:

At the command prompt type:

  • show portallocation [-srcIP <ip_addr ipv6_addr>] -destIP <ip_addr ipv6_addr> -destPort <port> -protocol <1 for TCP, 0 for non-TCP protocol>

Example - total number of free ports available on a standalone Citrix ADC appliance:

> show portallocation -destip 198.51.100.30 -destport 80 -protocol 1

        Freeports available : 64505
 Done


> show portallocation -srcip 192.0.2.30 -destip 198.51.100.30 -destport 80 -protocol 1

        Freeports available for IPAddress 192.0.2.30 : 20505
 Done
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Example - total number of free ports available on a Cluster setup:

The following example output displays the total number of free ports available on each node of a two node cluster setup.

> show portallocation -destip 198.51.100.30 -destport 80 -protocol 1

    Node Id: 1
    Freeports available : 32321

    Node Id: 0
    Freeports available : 32184

Done
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Monitor the ports usage on a Citrix ADC appliance for back-end connections using SNMP

You can use the PORT-ALLOC-EXCEED SNMP alarm to monitor the ports usage on a Citrix ADC appliance for back-end connections.

PORT-ALLOC-EXCEED SNMP alarm includes the high-threshold and normal-threshold parameters, which specify the total allocated ports of the Citrix owned IP addresses as percentages. For example, if the high-threshold parameter is set to 90, the Citrix ADC appliance generates and sends trap messages when the following event happens:

  • when the port allocation percentage exceeds 90 percent on any of the Citrix ADC owned IP address for the back-end connections

The SNMP alerts help you in deciding the need for more Citrix owned IP addresses if the free ports available are nearing exhaustion.

To Monitor the ports usage on a Citrix ADC appliance for back-end connections using SNMP

At the command prompt type:

  • set snmp alarm PORT-ALLOC-EXCEED -logging ( ENABLED DISABLED ) -severity <severity> -state ( ENABLED DISABLED ) -thresholdValue <positive_integer> [-normalValue <positive_integer>] -time <secs>
  • sh snmp alarm PORT-ALLOC-EXCEED

Example:

> set snmp alarm PORT-ALLOC-EXCEED -logging ENABLED  -severity Major -state ENABLED -thresholdValue 90 -time 1200
Done

> sh snmp alarm port-alloc-EXCEED

Alarm                   Alarm Threshold     Normal Threshold    Time    State       Severity        Logging
-----                   ---------------     ----------------    ----    --------    -------------   --------
1) PORT-ALLOC-EXCEED    80                  80                  7200    ENABLED     Major           ENABLED
Done

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For more information on configuring SNMP alarms and SNMP trap listeners, see Configuring the Citrix ADC to generate SNMP traps.

Monitor the free ports available on a Citrix ADC appliance for a new back-end connection