How to establish host-to-host (H2H) network connections for remote migration?

How to establish host-to-host (H2H) network connections for remote migration?

What is H2H Connection

Host-to-Host (H2H) connections are optimized one-way TCP-based network connections that cirrus-migrate-cloud uses to facilitate remote-migration, which features always-on compression and encryption.

By design, NO PRODUCTION DATA / I/O leaves the production network during the entire migration phase. As a result, direct connectivity between the source and destination host is required.

Network Requirement

Unless specifically specified, H2H connection uses port 4996 for communication.

H2H Connection is a one-way connection only and can be established in either direction. Ports and firewall rules only have to be opened on one of the servers (source or target).

For example, for cloud migration back to on-premises, it might be easier to open up the inbound rule at the cloud, as it often takes a lengthy approval cycle for on-premises datacenters to change inbound firewall rules.

How to setup

To create a H2H connection, go to Host --> H2H Connections --> Create.
Specify the "from host" and "to host."
Enter a connection IP / Hostname. Most of the time, this will be the receiver host's IP address, unless more complex network configuration is involved.

H2H connectivity can be established to/from any direction and is NOT tied to migration direction.

Regardless of which host is source / destination, connectivity can be established for:

Source --> Destination
Destination --> Source

While the network connectivity direction is usually the same as the migration direction, "Destination --> Source" may be used in cases where it is more convenient to configure the network security / firewall on the source side.

For example, when migrating from public cloud to on-premises, it is easier for the Cloud side to simply add an Inbound rule to the Security Group that allows TCP port 4996 inbound from the On-prem datacenter. Make sure to also check that the built-in firewall of the host itself is also changed to open TCP port 4996 inbound. For instructions on how to configure the host-side firewall settings, please read How to open up TCP ports in Linux/Windows OS-level Firewall?


Updated on: 11/07/2022

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