How to configure LLT over Ethernet with tagged VLAN interfaces or NIC Teaming that have the same MAC Addresses in a Microsoft Windows environment

Problem

In tagged VLAN network configurations or NIC teaming environments, there are multiple independent logical network interfaces that are created within a physical network interface or a teamed network interface. Each of these logical network interfaces may have the same MAC address.

When configuring a VCS cluster, the Veritas Cluster Configuration Wizard enables you to select the interfaces/MAC address for each heartbeat. While selecting the interface, if the logical interfaces that share the same MAC address is chosen with other logical interfaces, the LLT may use an interface other than the one selected. This issue occurs because the LLT Heartbeat uses the MAC address of the interface to monitor and determine the status of the heartbeat. Since the MAC address of all the logical interfaces are the same, the LLT may fail to identify the specifically selected virtual interface.

Issue 1
When using InfoScale for Windows with tagged vLan interfaces or NIC teaming configurations, the cluster configuration Wizard will not complete if all the NICs share the same MAC address.

Issue 2
When using InfoScale for Windows with tagged vLan interfaces or NIC Teaming software, all of the virtual NICs have the same MAC address. Traditionally, InfoScale for Windows uses the unique MAC addresses to identify each physical NIC. Another identifier is needed to distinguish each virtual NIC for use as the cluster heartbeats. Manual configuration of the LLT over Ethernet (cluster heartbeats) is required.

Solution

Step 1

Option A :  Create a Microsoft Loopback adapter to generate an additional NIC\MAC address for the cluster configuration wizard to complete on each node in the cluster.

Option B : If additional NICs exist on each node that is not in a team with a unique MAC address, use these NICs to configure the cluster.

Option C: If the Teamed NICs need to be used, this is possible, but Option A or Option B will need to be done temporarily.

1. Run and complete the cluster configuration Wizard using the NIC from Step 1 (Option A) or additional NICs not part of NIC team (Option B).

2. Manually modify the cluster configuration file llttab.txt. Modify this file with the Unique GUID for each interface card that will be used as part of cluster heartbeat. Please follow the steps below to manually edit the llttab.txt file

3. Run the following from a command prompt (Run as Administrator)

haconf -dump -makero
hastop  -local -force

4. On all nodes in the cluster, run the following command from a command prompt (Run as Administrator)

net stop llt /y

5. Step 4. Manually Configure LLT over Ethernet using the NIC "Interface GUID" in the llttab.txt file on all nodes in the cluster:

Location of the llttab.txt file: <drive_letter>\Program Files\Veritas\comms\llt\llttab.txt

Example of the llttab.txt file before any changes are made:
=============================================================================
LLTtab file Example Before:
# This is a program generated file. Please do not edit.
set-node SERVER1
set-cluster 1
link Adapter0 00:50:56:05:11:AC - ether - -
link Adapter1 00:50:56:05:11:AB - ether - -
#disable LLT broadcasts
set-bcasthb 0
set-arp 1
=============================================================================

5. In order to get the unique GUI for each interface, please run the following command from a command prompt (Run as Administrator)

    netsh trace show interfaces

Note: This command will give you the Unique Interface GUID for each NIC card on the server.

Example of output:

=============================================================================
C:\Users\administrator>netsh trace show interfaces

Ethernet adapter Public:
    Description:     Intel(R) PRO/1000 MT Network Connection
    Interface GUID:  {FC8FE5B0-0BF0-41F2-AFB8-40CF932CAE4B}
    Interface Index: 10
    Interface Luid:  0x6000005000000
Ethernet adapter HB1:
    Description:     Intel(R) PRO/1000 MT Network Connection #
    Interface GUID:  {0D45572B-AD5F-4298-800A-901DB17F5381}
    Interface Index: 15
    Interface Luid:  0x6000019000000
Ethernet adapter HB2:
    Description:     Intel(R) PRO/1000 MT Network Connection #
    Interface GUID:  {CD18F66E-ADD3-4B58-AD52-B88B0CE2C773}
    Interface Index: 14
    Interface Luid:  0x6000015000000
 
=============================================================================

6. Identify the Network Interfaces you would like to use as the cluster heartbeat by using the "description" field

7. Copy the "Interface GUID" including the brackets for each network interface you would like to use as the cluster heartbeat into the LLTtab file.

Example of the LLTtab file after the changes have been made correctly:

# This is a program generated file. Please do not edit.
set-node SERVER1
set-cluster 1
link Adapter0 {CD18F66E-ADD3-4B58-AD52-B88B0CE2C773} - ether - -
link Adapter1 {0D45572B-AD5F-4298-800A-901DB17F5381} - ether - -
#disable LLT broadcasts
set-bcasthb 0
set-arp 1

Note: If a Microsoft Loop Back Adapter was used to configure the cluster, this adapter must be taken out of the LLTtab file.
   
8. Repeat steps 4-7 on each node in the cluster. Each cluster node will have a unique GUID for the NICs on the server, so this file will need to be modified accordingly. The file is different on each node of the cluster and all nodes will need to have this file edited manually.

9. Save the LLTtab files on each node. Delete the Microsoft loop back adapter that is no longer in use on each node if necessary.

10. On one of the nodes in the cluster, open a command prompt (Run as Administrator) and run the following command:

hastart -all

11. Run the following command until it returns RUNNING for all nodes in the cluster. This can take up to 30 seconds.

hasys -state

Note: After modifying the LLT tab with the unique identifiers for the interfaces, the VCW wizard will no longer function. You will not be able to use VCW wizard to modify/edit the existing cluster configuration.