Limitations and usage guidelines

The following are the limitations and some usage guidelines related to Citrix ADC BLX appliances.

  • The following are the limitations related to LA/LACP channels:
    • LA/LACP channels are not supported for shared mode NIC interfaces.
    • LA/LACP channels are supported only between dedicated NIC interfaces or only between DPDK NIC interfaces.
    • LA/LACP channels are not supported for blx1 and ns1 virtual interfaces.
  • High availability is supported for Citrix ADC BLX appliances only in dedicated mode.

  • High availability for ADC BLX appliances is not supported if the nsinternal user login is disabled.

  • Web application firewall (WAF) is supported only for ADC BLX in dedicated mode.

  • In a Citrix ADC BLX appliance deployed in dedicated mode, management HTTP or HTTPS port (mgmt-http-port or mgmt-https-port) settings specified in the BLX configuration file do not apply. By default, 9080 and 9443 port numbers are dedicated for HTTP and HTTPS management access.

    To change these ports for ADC BLX appliances in dedicated mode, you must use the Citrix ADC command:

    set ns param (-mgmthttpport <value> | -mgmthttpsport <value>).

    Example:

    set ns param -mgmthttpport 2080"

  • If firewall is enabled on the Linux host, then you might have to add exceptions for the Citrix ADC BLX management ports in addition to the SYSLOG ports.

  • A stable start for a Citrix ADC BLX appliance might take around 45 seconds.

  • Citrix ADC BLX configurations are stored in the /nsconfig/ns.conf file. For configurations to be available across sessions, you must save the configuration after every configuration change.

    To view the running configuration by using the Citrix ADC BLX CLI

    At the Citrix ADC BLX CLI prompt, type:

    show ns runningConfig

    To save configurations by using the Citrix ADC BLX CLI

    At the command prompt, type:

    save ns config

  • The Citrix ADC BLX configurations in /nsconfig/ns.conf take precedence over /etc/blx/blx.conf file.

  • A Citrix ADC BLX appliance does not start if the memory allocated is less than 1 GB per ADC BLX worker-processes.

  • The following system settings are changed on installing a Citrix ADC BLX appliance in Linux environment: ip_forward is set to 1.

  • After a Citrix ADC BLX appliance is uninstalled, BLX configuration file blx.conf is retained and backed up as blx.conf.rpmsave.

    To apply this backup configuration file to a newly installed Citrix ADC BLX appliance on the same Linux host, you must manually rename the file back to blx.conf

Limitations specific to a Citrix ADC BLX appliance with DPDK support

  • A Citrix ADC BLX appliance with DPDK support might fail to start on Linux hosts running on some older CPU models.

    Examples:

    • Intel(R) Xeon(R) CPU E5-2690 v4 @ 2.60 GHz

    • Intel(R) Xeon(R) CPU E5504 @ 2.00 GHz

  • The Linux host might crash if you unbind NICs bound to the DPDK module when the Citrix ADC BLX appliance is running.

  • A Citrix ADC BLX appliance with DPDK support takes a little more time to restart as compared to a Citrix ADC BLX appliance without DPDK support.

  • DPDK configurations (DPDK IGB UIO insertion, DPDK bound ports, and huge pages) on the Linux host are lost whenever the host is restarted. Because of this reason, the Citrix ADC BLX appliance will fail to start after the Linux host is restarted. You must reconfigure DPDK for the Citrix ADC BLX appliance on the Linux host every time the host is restarted.

    For more information on configuring DPDK on the Linux host, see Configure DPDK on the Linux host.

  • All DPDK bound Linux NIC ports are automatically dedicated for the Citrix ADC BLX appliance and cannot be used for other DPDK Linux applications.

Limitations of Mellanox NICs in a Citrix ADC BLX appliance with DPDK support

  • A Citrix ADC BLX appliance supports only one type of DPDK NICs at a time. For example, either all Mellanox NICs or all Intel NICs.

  • A Citrix ADC BLX appliance supports only the MLX5 DPDK driver for Mellanox NICs.

  • For more information about the MLX5 DPDK driver and its limitations, see the official MLX5 DPDK documentation.

  • For more information about Mellanox NICs and its limitations, see the official Mellanox documentation.

Limitations and usage guidelines