How does nlb multicast work

SafeKit is a shared-nothing cluster: easy to deploy even in remote sites. A shared disk cluster is complex to deploy. Application HA supports hardware failure and software failure with a quick recovery time RTO around 1 mn or less. Full virtual machines HA supports only hardware failure with a VM reboot and a recovery time depending on the OS reboot. Smooth upgrade not possible. No dedicated server with SafeKit.

Each server can be the failover server of the other one. Software failure with restart in another OS environment. Secondary server dedicated to the execution of the same application synchronized at the instruction level.

Software exception on both servers at the same time. SafeKit implements real-time synchronous replication with no data loss in case of failure. With asynchronous replication, there is data loss on failure. SafeKit implements real-time byte-level file replication and is simply configured with application directories to replicate even in the system disk. Block-level disk replication is complex to configure and requires to put application data in a special disk. To avoid 2 masters, SafeKit proposes a simple split brain checker configured on a router.

To avoid 2 masters, other clusters require a complex configuration with a third machine, a special quorum disk, a special interconnect. No dedicated proxy servers and no special network configuration are required in a SafeKit cluster for virtual IP addresses. Special network configuration is required in other clusters for virtual IP addresses. Note that SafeKit offers a health check adapted to load balancers. This video shows a mirror module configuration with synchronous real-time replication and failover.

The file replication and the failover are configured for Microsoft SQL Server but it works in the same manner for other databases. The load balancing and the failover are configured for Apache but it works in the same manner for other web services. Microsoft NLB multicast mode As explained in the knowledge base of VMware , in the case of Microsoft NLB multicast mode , you need to manually configure static ARP resolution at the switch or router for each port that connects to the cluster.

Other differentatiors to consider when choosing a load balancing cluster. This choice instructs the cluster members to respond to the ARPs for their virtual address with the use of a multicast MAC address, such as A static MAC address is required in order to reach the cluster outside of the local subnet. The virtual IP address is Enter this command in order to populate the ARP table statically: arp In order to avoid this flooding, insert a static mac-address-table entry in order to switch the cluster-bound packets in the hardware: mac address-table static This removes the need to manually program the MAC address to the port maps that are required in Multicast mode in order to prevent flooding to the VLAN.

Since the virtual IP address uses a multicast MAC address, it is unreachable outside of the local subnet. Complete this in the same fashion as with Multicast mode.

For example, if the virtual IP address is View the bug details for the code releases that address this issue or use the IGMP snooping querier feature. View the bug details for the affected code versions. The port-channel must be cabled so that all of the member links are on the same forwarding engine. It is important that you configure the default gateway of the Microsoft Server to this address. The arp The mac address-table static The ip igmp snooping querier address It is important that you configure the default gateway of the Microsoft Server to this address ip address Verify Use this section to confirm that your configuration works properly.

Microsoft could have easily not included it with the OS, leaving the only option as an expensive hardware load balancer. MS NLB does work, and providing you are aware of and can address its limitations, you may find it to be an effective low cost load balancing solution in your environment. On the flip-side, if you find that the management and overhead is too much and you need a hardware LB device, there are a number of powerful and relatively inexpensive possibilities.

The ones from Barracuda Networks are a good choice. There are also other factors not covered here that need to be taken into account; session support, affinity, and redundant network topologies to name a few. So make sure to do adequate research, up to and including packet captures to prove intended operation. Install Terraform on Windows Create a. NET Core 3. Tags: multicast , nlb , unicast , wlbs. All Rights Reserved. Oct