Log Insight: External Load Balancer Configurations

I have heard many requests from people looking for how to configure an external load balancer (LB) to balance the traffic for a Log Insight cluster. This post provides directions for some popular LBs.


Here are a few important terms that will be used throughout this post:

  • VIP = Virtual IP (where events should be sent)
  • Pool = Log Insight cluster
  • Node = Log Insight instance
  • LB = Load Balancer
  • SNAT = Source Network Address Translation


I covered high-level LB information during the Log Insight 2.0 beta here, but would like to reiterate the considerations as they are critical for LB configuration:

  • UDP – assuming you are sending events over UDP (the standard for most systems today), you need a load balancer that supports UDP traffic.
  • TCP – syslog TCP connections are often, what are referred to as, “long-lived” TCP sessions. This means unless the syslog process on the client is restarted or there is a network interruption between the client and the server, the client will establish and keep open a connection with the server (or in the case of a Log Insight cluster, a single node in the cluster). This can lead to cluster imbalances overtime (more on this in a future post).
  • Algorithm – the default load balancer algorithm is typically round robin. To address potential load imbalance in the base of Log Insight node maintenance, using the least connections algorithm is recommended.
  • Connections – it is important that the load balancer used is capable of supporting the number of connections required for your environment. For a full-scale cluster, some load balancers are not capable of handling the combination of the number of connections with the number of events sent per connection resulting in dropped messages.
  • Throughput – syslog traffic is light and traffic for a full-scale cluster only pushes about 200MB/s. This rules out developer licenses for many load balancers.
  • SNAT – while not specific to syslog traffic, it is important to note that unless the load balancer is also acting as a router that you will need to configure SNAT (Source NAT) for the traffic to be passed properly.

In regards to the configuration information listed below, I will be skipping information that is not about configuring the cluster. It will be important that you configure these as appropriate for your environment:

  • High Availability (HA) – one of the reasons why you might choose to use a Log Insight cluster is for ingestion HA. I will not be covering how to configure HA on the load balancers listed in this post.
  • Firewall rules (security) – for security reasons, you may wish to restrict which systems can talk to Log Insight. I will not be covering how to configure firewall rules on the load balancers listed in this post, but reference the Log Insight security guide for port/protocol requirements.

For each LB defined below the following sections may be used:

  • Terms – specific to the LB being defined
  • Manage – how to mange the LB being defined
  • Deploy – how to stand-up a new instance of the LB being defined
  • Change pool – you may need to make changes to the pool over time for things such as expanding/reducing the cluster size and handling cluster maintenance.
  • Troubleshooting – tips and tricks on how to resolve issues

Finally, in terms of LB configuration it is important to understand the steps required:

  1. Deploy the LB
  2. Manage (log in) to the LB
  3. Perform initial configuration – as appropriate for your environment
  4. Define nodes – needs to be repeated for each node in a cluster
  5. Define pool – only one per cluster
  6. Add nodes to pool
  7. Define VIP – only one per cluster, but multiple protocols per VIP depending on environment requirements
  8. Add pool to VIP
  9. Verifications – ensure everything is green on the LB and ensure when sending traffic to VIP, Log Insight receives it
  10. Usage – point all devices to the VIP via FQDN



  • vCNS = vCloud Network and Security (aka vShield and soon to be NSX)
  • vSM = vShield Manager
  • vSE = vShield Edge
  • VDS = Virtual Distributed Switch

Manage vSE

  • Log into vShield Manager
  • Expand Datacenters
  • Select Datacenter for vSE
  • Select Network Virtualization tab in right pane

Deploy vSE

  • While on the Network Virtualization tab in right pane, select the green plus icon
  • Give the vSE a name and enable/configure HA (outside the scope of this post)
  • Select Next
  • Configure CLI credentials as appropriate and select Enable SSH access if desired
  • Select Next
  • Under Edge Appliances leave Appliance Size unless running large Log Insight instance in which case select Quad Large
  • Under Edge Appliances select the green plus
  • Select Cluster/Resource Pool
  • Select the Datastore
  • Select Add
  • Select Next
  • Select the green plus for Interfaces
    • For name enter Uplink
  • Under Configure Subnets select the green plus
    • Under Add Subnet select the green plus
    • In the IP address dialog box, enter a static IP
    • Select OK
    • Enter the Subnet Mask
    • Select Save
    • Select Add
    • Select checkbox to configure default gateway
    • Enter gateway IP
    • Select Next
  • (Optional) Select Configure Firewall default policy
  • For Logging select Enable
  • Select Next
  • Select Finish
  • Double click VSE
  • Under Details select Change
  • In Syslog Server 1 enter the FQDN of the Log Insight instance to collect vSE logs
  • Select Save
  • Select the Configure tab
  • Select the pencil
  • Select Select
  • Select Distributed Portgroup
  • Select radio button
  • Select Select
  • Select Save
  • Select the Load Balancer tab
    • Select the green plus
    • Enter a name for the pool
    • Select Next
    • Select the checkbox next to TCP and change the port to 514
    • Select Next
    • Change monitor port to 514 for TCP
    • Select Next
    • Select the green plus
    • Enter IP address of a node and change monitor port to 514
    • Select Add
    • Select Next
    • Select Finish
    • Repeat above steps for all nodes
    • Repeat above steps for TCP 9000, TCP 1514, and TCP 6514
  • Select Publish Changes
  • Select Virtual Servers
  • Select the green plus
  • Give the VIP a name
  • Enter an IP address for the VIP (use the same as the interface you manually configured)
  • From the Existing Pool drop-down select the pool to add to the VIP
  • Under Services
    • Select the checkbox box next to TCP and change the port to 514
    • Add one for TCP port 9000, TCP 1514, and TCP 6514
  • Scroll down and select the Enable logging checkbox
  • Select Add
  • Select Publish Changes
  • Select Pools
  • Select Enable
  • Select Publish Changes

Change pool

  • Access the Network Virtualization tab
  • Double click VSE for which you want to update the LI Nodes
  • Select the Load Balancer tab
  • Select the pool and select the pencil icon
    • Select Next
    • Select Next
    • Select Next
    • Modify members as desired (add/remove/change master/workers)
    • Select Next
    • Select Finish
  • Select Publish Changes


  • From the Log Insight instance you are forwarding logs to, query for source contains <FQDN_or_IP> of vSM and/or vSE


Manage F5

  • Log into F5 (https://<FQDN_or_IP>) (admin/<password>)
  • Local Traffic – where all VIP/Pool/Node/Monitors are configured
  • Statistics – helpful for monitoring status and checking LB health

Create/Change nodes

  • Follow the directions in the Manage F5 section above
  • Under Local Traffic select Nodes
  • Select Create
    • Enter name of LI instance
    • Enter IP address of LI instance
    • Select Repeat if you need to add more nodes else select Finished


Create/Change pool

  • Under Local Traffic select Pools
  • Select Create
    • Enter a name for the pool
    • Under Health Monitors focus on Available, scroll down and select TCP
    • Select the left arrow to move to Active
    • Select Finished
  • Under Members for the Pool select 0
  • Select Add
    • Under Address select Node List
    • Select the node to add to the pool
    • Under service port enter 514
    • Select Repeat to add more nodes else Finished

Create VIP (Virtual Servers)

  • Follow the directions in the Create/Change pool section above
  • Under Local Traffic select Virtual Servers
  • Select Create
    • Enter a name for the VIP – recommended format: <clusterName>-<tcp|udp|api> (e.g. li1-tcp, li1-udp, li1-api…)
    • Enter Destination Address – should be unique per Log Insight cluster configured on LB
    • Under Service Port enter: tcp=514, udp=514, tcp=1514, tcp=6514, tcp=9000
    • Under Protocol, select the protocol desired (all TCP except UDP)
    • If another protocol is needed select Repeat else select Finished (note: changing to UDP seems to fail so select Finished and then select Create for UDP)
  • For each VIP, select Edit under Resources
    • For Default Pool select the cluster Pool you created earlier (e.g. li1)
  • Select Update


Manage Riverbed

  • Log into Riverbed (https://<FQDN_or_IP>:9090) (admin/<password>)
  • Validate that all clusters to be tested are green on the Home tab

Create/Change virtual servers

  • Select Services
  • Select Pools tab
    • Scroll down to Create a new Pool
    • Pool Name: <clusterName>-<protocol> (e.g. li1-udp)
    • Nodes: Enter the IP address of each node for the protocol (api/tcp/udp all 6 nodes)
    • Monitor: Connect
    • Select Create Pool
    • When you are done you should have 5 pools per cluster (api/tcp/udp) and each should have a green check mark


  • Select Virtual Servers
    • Scroll down to Create a new Virtual Server
    • Virtual Server Name: <clusterName>-<protocol> (e.g. li1-udp)
    • Protocol: api/tcp daemon/query = generic client first, udp = udp-streaming
    • Port: api = 9000, tcp = 514, udp = 514, tcp = 1514, tcp = 6514
    • Default Traffic Pool: <clusterName>-<protocol> (e.g. li1-udp)
    • Select Create Virtual Server
    • Under Basic Settings > Listening on: Select Traffic IP Groups and select the checkbox next to <clusterName> (e.g. li1)
    • Under Basic Setting > Enabled: Select Yes
    • Select Update
    • When you are done you should have 5 virtual servers per cluster (api/tcp/udp/tcp[ssl-esxi]/tcp[ssl]) and each should have a green check mark

  • Select Home
    • Verify the virtual server is shown in green

Create/Change traffic managers (VIP)

  • Select Services
  • Select Traffic IP Groups
    • Scroll down to Create a new Traffic IP Group
    • Name: <clusterName> (e.g. li1)
    • IP Addresses: enter a static IP address
    • Select Create Traffic IP Group


  • How can I tell what clients are sending traffic to the LB – the issue is when using a LB the source field in LI becomes the LB
    • Select Activity
    • Select Connection tab
    • Add a filter for what you are looking for (e.g. Virtual Server equal li1-tcp)
    • Select Update filters
    • Look at the From column
  • How can I check the LB load?
    • Select Activity
    • From Current Activity under Settings, select a Chart data option
    • If you do not like the Chart data options select Change data
    • Select the fields you care about and give it a name



Note: Kemp is the best choice of external load balancer for Log Insight 2.0 because it offers message rebalancing of events through a Log Insight specific add-on pack. No other external load balancer provider offers this functionality out of the box!
I could list all the steps here, but Kemp has done a great job putting together a document that covers all the steps here.


This post demonstrates how to configure some common LBs to work with a Log Insight cluster. Other LBs, including HAproxy, NGINX, and Cisco ASA could be used as long as the Log Insight considerations are followed.
Note: if you need UDP load balancing and you are looking for an open-source/free alternative to HAproxy/NGINX since neither have UDP load balancing, check out Zen.

© 2014 – 2021, Steve Flanders. All rights reserved.

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