Citrix NetScaler (Update)

Almost 3 years ago I evaluated and implemented for my ex company F5 BIG-IP 8950 load balancer; now for my new company I start implementing Citrix NetScaler VPX for our Windows infrastructre (Lync, Exchange and Citrix). Here a short overview how it is integrate in the two data centre’s:

From the first look I like the NetScaler, the CLI is a bit easier to understand from what I think but will see how it goes over the next weeks regarding balancing compare to F5 😉

I like the policy based routing implementation on the Netscaler, here a short example:

add ns pbr mgmt-access ALLOW -srcIP = -destIP = -nextHop -priority 10

Access to the will be routed to the gateway even you have a default gateway configured what shows to another direction.

In my set-up you need to configure policy based routing if server in the Windows backend network try to access virtual server IPs in the LB-Transfer network otherwise you have asymetric routing.

add ns pbr VIP-WIND-DC02 ALLOW -srcIP = -destIP = -nextHop -priority 11

Configure syslog server on F5 BIG-IP

Syslog servers are a great idea they centralise all your logs from your Servers and networking devices.

I used for the syslog server the following command

bigpipe syslog remote server '' host add

After that everything looked fine and I saw syslog messages but I got lots of informational messages and the following debug message.

debug snmpd[PID]: error on subcontainer 'ia_addr' insert (-1)

For the debug message I found a solution on AskF5:

There is saw that I went the wrong way of configuring syslog on my load balancer, I also needed to set the log level for remote syslog server. Here the solution from F5:

1. Log in to the command line of the BIP-IP

2. Create in /tmp/ file with the syslog configuration.

syslog include "
filter f_remote_loghost {
destination d_loghost {
udp(\"\" port(514));
log {

3. To remove the currently configured remote syslog servers, type the following command:
Important: This step disables all remote logging.

[[email protected]:Active] tmp # b syslog remote server none

4. Copy the changes into the configuration

[[email protected]:Active] tmp # bpsh < /tmp/

5. Refresh and start syslog deamon

[[email protected]:Active] tmp # syslog-ng -s

6. Save the configuration

[[email protected]:Active] tmp # b save all
/config/bigip_base.conf was renamed to /config/bigip_base.conf.bak (86 lines).
/config/bigip_sys.conf was renamed to /config/bigip_sys.conf.bak (66 lines).
/config/bigip.conf was renamed to /config/bigip.conf.bak (894 lines).
/config/bigip_local.conf was renamed to /config/bigip_local.conf.bak (1 lines).
[[email protected]:Active] tmp #

If the new logging configuration is not working as expected, make the desired changes to the /tmp/ file and return to Step 2.

When the syslog-ng -s command reports the following error message:

# syslog-ng -s syntax error at 751

Remove the syslog include entries by typing the following command:

bigpipe syslog include none

Review the import configuration for syntax errors before attempting to re-import by typing the command listed in Step 2.

F5 BIGIP Software upgrade procedure

Here is a procedure on how to upgrade the software on an F5 BIGIP cluster tier.

  1. Download last ISO version for F5 BIGIP LTM
  2. Upload the ISO to the standby unit
  3. Install the ISO to a free partition on the standby unit
  4. Change boot location to the new partition and device automatically reboots.

After 6 to 7 minutes the device booted with the new software version. From now on you won’t be able to sync your configs between the devices anymore because of the different software versions it’s only possible within the same release. F5 doesn’t recommend to run cluster with different software versions.

Now initiate the failover on the active unit! Do that maybe at low traffic period! Normally there should be no side effect and the failover is not visible to clients because of the mirroring the sessions.

In case of problems with the new software version you should be able to switch back to the other cluster member with the old software version at any time.

  1. When you verify that everything is working after the failover you can start the other device now
  2. Upload ISO file
  3. Install ISO file
  4. Change boot location

The same procedure you use to install hotfixes on the BigIP.

F5 Load Balancer

My company decided to buy two F5 Big IP Local Traffic Manager 8950 for our web cluster systems with a maximum balanced capacity of 20 gigabit. We also got the F5 Local Traffic Manager as Virtual Edition for our test enviroment and to integrate it into the test network.

In the beginning the F5 looked very complicated but after some time now playing around with it and setting up things, it got easier and easier. I only need to have a deeper look at the iRules because this feature allows you can to really do everything with the F5 load balancer.

So for now I can’t really write more about it but I will soon  post some updates.

Next week I have the integration of the F5 Big-IP into the production network of my company and will start setting up the first new linux web cluster but only with a layer 4 balancing.


Here a nice picture of the new F5 BigIP boxes in the data center from my company:

For the new web cluster for my company we set-up layer 4 balanced web server pools and layer 7 balanced pools.

The layer 7 balancing was necessary because there where different server pools with applications that needed to run under the same domain and where routed on the expected http/https request. I will post the iRule for everybody soon.

Here two interesting ressources to get information:

Ask F5

F5 Devcentral