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ClusterXL association between cluster Virtual IP addresses and MAC Addresses
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  1. ClusterXL offers two separate High Availability modes - New and Legacy (Traditional).

    • ClusterXL uses the New High Availability mode to associate cluster Virtual IP addresses with physical MAC addresses of the Active cluster member.

      By binding Virtual IP addresses to Unicast MAC addresses, ClusterXL ensures that all packets sent to the cluster acting as a Default Gateway will reach the Active cluster member.

      Active cluster member then processes all packets by itself (traffic load is not shared).

      In case of a failure on the current Active member, failover takes places, and Standby member becomes the new Active member. The cluster Virtual IP addresses become associated with physical MAC addresses of the new Active cluster member.

      Note: Additional feature was developed to associate cluster Virtual IP addresses with Virtual MAC addresses. Refer to sk50840 (How to enable ClusterXL Virtual MAC (VMAC) mode). In case of a failure on the current Active member, failover takes places, and Standby member becomes the new Active member. The cluster Virtual IP addresses are still associated with the same Virtual MAC addresses.

    • In Legacy High Availability mode there are no Virtual IP addresses - the cluster members share identical IP and MAC addresses, so that the Active cluster member receives from a hub or switch all the packets that were sent to the cluster IP address.


  2. ClusterXL offers two separate Load Sharing modes - Unicast and Multicast.

    The two modes differ by which MAC address is associated with the cluster Virtual IP address and how the traffic load is shared.

    • ClusterXL uses the Load Sharing Unicast mode to associate cluster Virtual IP addresses with physical MAC addresses of the Pivot cluster member.

      By binding Virtual IP addresses to Unicast MAC addresses, ClusterXL ensures that all packets sent to the cluster acting as a Default Gateway will reach the Pivot cluster member.

      Pivot cluster member then decides whether or not it should process the packets by itself, or forward the packet to other non-Pivot memebers by applying a special algorithm described in sk34668 (How to modify the assigned load between the members of ClusterXL in Load Sharing Unicast mode).

      In case of a failure on the current Pivot member, failover takes places, and non-Pivot member becomes the new Pivot member. The cluster Virtual IP addresses become associated with physical MAC addresses of the new Pivot cluster member. Traffic load is shared amongst the remaining cluster members based on the same algorithm.

      Note: Additional feature was developed to associate cluster Virtual IP addresses with Virtual MAC addresses. Refer to sk50840 (How to enable ClusterXL Virtual MAC (VMAC) mode). In case of a failure on the current Pivot member, failover takes places, and non-Pivot member becomes the new Pivot member. The cluster Virtual IP addresses are still associated with the same Virtual MAC addresses.

    • ClusterXL uses the Load Sharing Multicast mode to associate cluster Virtual IP addresses with all cluster members.

      By binding Virtual IP addresses to Multicast MAC addresses, ClusterXL ensures that all packets sent to the cluster acting as a Default Gateway will reach all cluster members.

      Each member then decides whether or not it should process the packets by applying the Decision Function.

      Traffic load is shared based on formula: 100% / (number of members in the cluster)

      In case of a failure on one of the members, the cluster Virtual IP addresses are still associated with the same multicast MAC addresses. Traffic load is shared amongst the remaining cluster members.

      In Load Sharing Multicast mode, the Multicast MAC address that is associated with Virtual IP address is calculated automatically (and can be changed manually).

      In order to see / change this Multicast MAC address:

      1. Open SmartDashboard.
      2. Open cluster object.
      3. Go to 'Topology' pane - click on 'Edit...'.
      4. Select the relevant VIP interface - click on 'Edit...'.
      5. On 'General' tab, click on 'Advanced...'.
      6. If you need to change this address, then select 'User defined:' and enter new Multicast MAC address.
      7. Click 'OK' in all windows to apply the changes.
      8. Save the changes: go to 'File' menu - click on 'Save'.
      9. Install policy.

      Automatic algorithm for generating a Multicast MAC address to be associated with cluster Virtual IP address of a format "A"."B"."C"."D":

      • If 2nd octet "B" < 127, then
        Final MAC = 01:00:5E:("B"hex):("C"hex):("D"hex)
        Example: VIP = 192.50.204.20
        Final MAC = 01:00:5E:("50"hex):("204"hex):("20"hex) = 01:00:5E:32:CC:14
      • If 2nd octet "B" > 127, then
        Final MAC = 01:00:5E:("B-128"hex):("C"hex):("D"hex)
        Example:
        VIP = 192.168.204.20
        Final MAC = 01:00:5E:("168-128"hex):("204"hex):("20"hex) = 01:00:5E:28:CC:14

 


 

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