Network Load Balancing

Video tutorials on NLB (WLBS)

2007-03-21T05:58:00.000-07:00

Don't you think having few training videos on NLB i.e. WLBS would just increase your overall understanding of WLBS. I am providing you a couple of links to Videos (CBT) on NLB. I hope it will help you immensely.

Happy learning!!!

Support WebCast: Network Load Balancing in Microsoft Windows 2000
This webcast is not available any more. To know about the contents of this webcast please download the PPT. Go to the page by clicking on the above url and then download the PPT. Click on this link to go to the transcript which describes each slide.

All about NLB (WLBS) click on me to get the microsoft document.

TechNet Webcast: Clustering Windows Server 2003 and SQL Server 2000 and 2005 (Level 200)

TechNet Webcast: Using Network Load Balancing on Windows Server 2003 and IIS 6.0 - Level 200

Support WebCast: Microsoft Windows Terminal Services: How to Configure Network Load Balancing

Clustering Windows Server 2003 and SQL Server 2000/2005 using NLB at front end.

How to troubleshoot common NLB problems.

2007-03-17T07:31:00.000-07:00

Following are the general steps that one may want to try while troubleshooting commong NLB (WLBS) issues like:

1) Nodes not converging.
2) Adding a node to the NLB cluster stops the cluster from working.
3) Unable to access NLB from another VLAN.
4) NLB not working properly.

1) First collect the "WLBS Display" logs from all the nodes. Compare them for any mismatching rule or Parameter. Try to find if you see frequent convergence happening. If you see lot of convergence happening but nodes never getting converged then you might want to check the heart beat communication.
If you find an error message like "cluster Mode Stopped" then again youmight want to check the heart beat communication as well as for any misconfiguration in the NICs. Also make sure that your NICs drivers are updated and you don't have teaming enabled on the nodes. Teaming causes lot of such issue. Moreover NLB cluster is not recommended with teaming enabled on the nodes.

2) Try to ping the VIP from the same V/LAN. Are you able to ping it? If yes then try to ping the VIP from different VLAN. If you are not able to ping the VIP from there then check the ARP table entry cached i the router/switch between the two VLANs. If you find that you are not able to ping the VIPs from either of the VLAN then go ahead and connect the Nodes to a hub. Now try to ping the VIPs. Are you able to do so? If yes you know where the problem is and if no then also you know where the problem is.

3) Try to ping the DIP of the nodes you should be able to do so. If not then you know where the problem is.

Make sure that you always use the layer two switches while using WLBS. Also recheck the configuration to find out if there is any mismatch. Make sure you break the teaming before you do any troubleshooting. Never use cross cable to connect the nodes for private (heart beat) communication. Make sure you NIC drivers are updated to the latest version.

If these steps doesn't prove helpful in identifying the issue then you may want to contact Microsoft support to resolve your issue.

Hope this helps.

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Best practices

To summarize, best practices for NLB cluster administrators:

Cluster administrators should establish a common administrative account on all NLB hosts that have Administrator privileges. To simplify cluster management, it is preferable that a single domain or global group account be used for this purpose.

The NLB subnet must be physically protected from intrusion by unauthorized computers and devices to avoid interference from unauthorized heartbeat packets.

NLBs remote control mechanism is disabled by default. It should remain disabled unless the administrator can ensure that the NLB subnet has been physically protected from intrusion and that UDP control ports 1717 and 2504 have been firewalled to prevent unauthorized remote control.

If remote control has been enabled, remote control operations using the NLB control program wlbs.exe must only be performed from a trusted computer within the firewall.

NLB Manager provides a secure method for remote cluster management and should be used instead of wlbs.exe whenever possible. NLB Managers optional host list file should only be saved to a file that is accessible by user accounts (such as the NLB cluster administrators account) that have local Administrator privileges.

NLB (WLBS) Resources

2006-12-28T01:33:00.000-08:00

NLB and IGMP

26) Limit switch port flooding

27) Selecting the Unicast or Multicast Method of Distributing Incoming Requests

28) Look for "Cluster Operation Mode on the Cluster Parameters tab" under "Network Load Balancing parameters"

29) Load balancing the VPN

30) Network Load Balancing vs. Hardware Load Balancing (CISCO Arrowpoint)

31) Integrating Microsoft's Network Load Balancing (Windows 2003 NLB) with ColdFusion MX 6.1

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Some Resources For Cluster NIC Configuration

1) Cluster Networking Requirements:

2) Procedures for Implementing Cluster Networking Best Practices:

3) Cluster Networking Best Practices:

4) Recommended Private “Heartbeat” Configuration on a Cluster Server

5) The effects of using Autodetect setting on cluster network interface card

6) MSCS FAQ

7) Windows 2000 Advanced Server supports two-node clustering

8) Microsoft Windows 2000 Datacenter Server supports four-node clustering.
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Network Load Balancing (NLB) and virtual machines

There is a fair amount of confusion about the state of using Windows network load balancing (NLB) when it comes to Microsoft virtual machines. Today I am (hopefully) going to set the record straight. When using NLB with Microsoft virtual machines you need to be aware of the following issues:Virtual Server / Virtual PC will not utilize any NLB capabilities on the host operating system. This is because Virtual Server / Virtual PC perform their network operations at a lower layer on the host network stack than NLB. Note - Virtual Server and Virtual PC will function correctly when NLB is present on the host - they will just not benefit from it.Virtual Server / Virtual PC have some network optimizations that actually cause problems when running NLB systems inside of virtual machines. These optimizations are simply that if we see a network packet that is going from the host to a virtual machine, or from a virtual machine to another virtual machine, we will send the packet directly to that virtual machine - without sending a copy of it on to the physical network connection. Similarly if we see a network packet coming into the physical computer that is destined for the host operating system - we will not send it on to any of the virtual machines.Now - these optimizations cause problems with NLB because NLB creates its own virtual MAC address that is shared amongst all the NLB servers - which means that we cannot tell when a packet should go just to the host, a virtual machine or everyone. Because of this we see the following results:NLB works with virtual machines - if everything (client and NLB servers) is on separate host systems. It also works if some systems are physical computers, and some virtual machines - as long as each server / client is on a separate computer.NLB works when all the NLB servers are virtualized and placed on the same physical computer. Obviously this is only useful for non-production environments.Any other configuration will fail (e.g. having a virtualized client hosted on a physical NLB server node, having a virtualized client and virtualized NLB server node on one box, with other NLB server nodes on remote systems) ==========================================================================

IIS and MSCS
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Web Server Clustering

Installing IIS on MSCS

How to Install the NTOP on Cluster Server

How to Install the NTOP on MSCS 1.0 with SQL Server 6.5 or 7.0

Installing NTOP on Cluster Server with SP4 Causes Event IDs 1009

Event Log Error 3221229574 from Service Control Manager

INFO: Stand Alone Distributed Transaction Coordinator Setup

Deciphering IISSYNC Status Codes

IISSYNC Returns a Status of 214598801

How to Install IIS 4.0 onto a Single Node of MSCS 1.0

Resolving MSDTC Conflicts During NTOP Installation on Cluster Server

NT 4.0 Option Pack Installation Errors on MSCS Running MSDTC

Computer Stops Responding When Creating IIS Server Instance

How to Enable Cluster Logging in Microsoft Cluster Server

Using IISSYNC to Synchronize Clustered Web Sites on Windows 2000