Load Balancing

Ratio Load Balancing

Go to Local Traffic > Pools and select www_pool and then Members from the top bar or you could click on the Members link in the Pool List screen.

Hint

When we created the pool, we performed all our configuration on one page, but when we modify a pool the Resource information is under the Members tab

Under Load Balancing section change the Load Balancing Method to Ratio (Member)

In drop-down menu, notice most load balancing methods have two options, (Node) or (Member).

Q1. What is the difference between Node and Member?

Select the first member in the pool 10.1.20.11:80 and change the Ratio of the member to 3

Open the pool statistics and reset the statistics for www_pool.

Browse to http://10.1.10.100 and refresh the browser screen several times.

Q2. How many Total connections has each member taken? Is the ratio of connections correct?

Now go back and put the pool back to Round Robin Load Balancing Method

Reset the pool statistics and refresh the virtual server page several times.

Q3. Does the ratio setting have any impact now?

Priority Groups Lab

Let’s look at priority groups. In this scenario we will treat the 10.1.20.13 server as if it was is in a disaster recovery site that can be reached over a backhaul. You want to maintain at least two members in the pool for redundancy and load. You would traffic to be distributed t0 10.1.20.13 only during maintenance of one on the two primary servers or if one to the two other pool members fails.

Note

Remove any caching profiles from the www_vs virtual server (10.1.10.100).

Go to the www_pool Members section. Make sure the load balancing method is Round Robin.

Set the Priority Group Activation to less than 2 Available Members.

Select the pool members 10.1.20.11 and 10.1.20.12 and set their Priority Group to 10.

Review your settings and let’s see how load balancing reacts now.

Select the Statistics tab, reset the pool statistics, browse to http://10.1.10.100 and refresh several times.

Q1. Are all members taking connections? Which member isn’t taking connections?

Let’s simulate a maintenance window or an outage by disabling a pool member 10.1.20.11:80 in the highest priority group. This should cause low priority group to be activated, since number of active members in our high priority group has dropped below 2.

Q2. Is the lower priority group activated and taking connections?

Select a member in the Priority Group 10 and Disable that pool member.

Once again, select Statistics, reset the pool statistics, browse to the virtual server and see which pool members are taking hits now.

Important

Once you are done testing re-enable your disabled pool member.

Simple (Source Address) Persistence

You have already seen cookie persistence at work, but if the client or application (ie. ftp) does not support cookies you must use and alternate method. The most common is Simple Persistence which is based on the source IP address/network.

Verify your www_pool is using Round Robin load balancing and the priority groups are disabled.

Browse to http://10.1.10.100 and refresh several times. You should see all 3 servers respond.

Go to Local Traffic > Profiles and select the Persistence tab and from the Persistence Profiles screen select the Create button.

Create a new persistence profile named my-src-persist with a Persistence Type of Source Address Affinity and set the Timeout to 120 seconds and leave Mask: None

Note

The Mask: None defaults to 255.255.255.255 which means each new IP address will create a new persistence record.

Now let’s attach the new persistence profile to the www_vs virtual server.

Hint

When you create a Virtual Server everything is on a single page, when you return to modified the Virtual Server the Properties and Resources are on different pages.

Set the Default Persistence Profile to my-src-persist.

Test your Source Address Affinity persistence profile.

At this point you may want to open a second browser window to the BIG-IP GUI.

Go to Statistics > Module Statistic > Local Traffic and select Persistence Records from the Statistics Type menu.

In this window, you can watch you persistence records. You may want to set Auto Refresh to 20 seconds.

In another BIG-IP GUI window go to www_pool and clear the member statistics.

Browser to http://10.1.10.100 and refresh several times.

Q1. How many members are taking traffic?

Q2. Check you Persists Records window, are the any persistence records?

Q3. Refresh you web page prior to the Age column reaching 120. What happens?

While the persistence recorded is still active Disable the member you are persisted too and refresh the browser page.

Q4. Could you access the web site? Why?

While the persistence recorded is still active, go the member specific menu of the member you are persisted too and do a Force Offline and refresh the browser page.

Q5. Could you access the web site? Why?

Important

Re-enable the pool members before continuing.