Configuring Host-Managed Networking in Qumulo Core

This section explains the difference between host-managed networking and Qumulo-managed networking, gives an overview of how host-managed networking works, and provides examples of networking interfaces with and without alternative names.

Prerequisites

When using the Product Package to install Qumulo Core, it is possible to install Qumulo Core by using host-managed networking, where the user configures and maintains the network, or Qumulo-managed networking, where Qumulo configures and maintains the network.

Because the Qumulo Core Product Package uses host-managed networking by default, no additional action is necessary to enable it. For Qumulo-managed networking, you must run the export QUMULO_MANAGED_NETWORK=true command before beginning the installation.

Note
You can use host-managed networking with or without the Qumulo REST API. However, using floating IP addresses requires tagging with alternative names and REST API access.

Configuring Interface Tagging with Alternative Names

In Linux, the alternative name (altname) is an optional, user-defined alias for a network interface. For more information see ip link in Linux documentation.

In Qumulo Core, alternative names let you use the Qumulo REST API to configure floating IP addresses for your Qumulo cluster and to assign the roles of front end (for client traffic) or back end (for inter-node traffic) to network interfaces. Without alternative names, Qumulo Core uses all valid and connected network interfaces.

To Enable Alternative Names

You can configure alternative names to be always enabled while systemd-networkd is operating.

To your /etc/systemd/network/ directory, add the file 10-altname.link.
Add the PCI address and altertative name for the network interface to the 10-altname.link file. For example:
```
[Match]
Path=pci-0000:01:00.0
[Link]
AlternativeNames=qumulo-backend
```
To enable the changes, restart systemd-networkd.

Note
If you use another networking manager, consult its documentation for information about enabling alternative names permanently.
To put your alternative names into effect, restart QFSD.

Assigning a Front-End of Back-End Role to a Network Interface

To assign the front-end role to a network interface, for serving client traffic, run the ip link command and specify the network interface name and the alternative name (which includes the network ID).

In the following example, the network interface name is eth0 and the alternative name is qumulo-frontend1 (the network ID is 1).
```
sudo ip link \
  property add \
  dev eth0 \
  altname qumulo-frontend1
```
To assign the back-end role to a network interface, for inter-node communication, run the ip link command and specify the network interface name and the alternative name.

In the following example, the network interface name is eth1 and the alternative name is qumulo-backend.
```
sudo ip link \
  property add \
  dev eth1 \
  altname qumulo-backend
```
Note
Qumulo Core permits only one interface to be tagged as qumulo-backend.

Example Configurations

This section gives examples of network configurations with and without alternative names for front-end client traffic, back-end inter-node traffic, and combined QFSD traffic.

Click to expand

Example Configurations with Alternative Names

Two Network Interfaces with a Link (Front-End and Back-End): In the following example, Qumulo Core labels interface eth0 as USE_FOR_FRONTEND and eth1 (the interface with a higher PCIe address) as USE_FOR_BACKEND.
```
sudo ip link \
  property add \
  dev eth0 \
  altname qumulo-frontend1
```
```
sudo ip link \
  property add \
  dev eth1 \
  altname qumulo-backend
```
Two Network Interfaces with a Link (Front-End and Back-End on the Same Link): In the following example, Qumulo Core labels interface eth0 with USE_FOR_FRONTEND_AND_BACKEND, and uses only eth0 for QFSD traffic.
```
sudo ip link \
  property add \
  dev eth0 \
  altname qumulo-frontend1
```
```
sudo ip link \
  property add \
  dev eth0 \
  altname qumulo-backend
```

Three Network Intefaces with a Link (Three Front-End and One Back-End on the Same Link): In the following example, Qumulo Core labels interfaces eth0 and eth1 as USE_FOR_FRONTEND and eth2 as USE_FOR_FRONTEND_AND_BACKEND.

sudo ip link \
  property add \
  dev eth0 \
  altname qumulo-frontend1

sudo ip link \
  property add \
  dev eth1 \
  altname qumulo-frontend2

sudo ip link \
  property add \
  dev eth2 \
  altname qumulo-frontend3

sudo ip link \
  property add \
  dev eth2 \
  altname qumulo-backend

Example Network Interface Labels without Alternative Names

One Network Interface with a Link: Qumulo Core labels the interface with USE_FOR_FRONTEND_AND_BACKEND.
Two Network Interfaces with a Link: Qumulo Core labels the interface with the lower PCIe address as USE_FOR_FRONTEND_AND_BACKEND and the interface with the higher PCIe address as USE_FOR_FRONTEND.
Three Network Interfaces with a Link: Qumulo Core labels the inteface with the lowest PCIe address as USE_FOR_FRONTEND_AND_BACKEND and the interfaces with the next highest an the highest PCIe addresses as USE_FOR_FRONTEND.

Note
Although the interface with the lowest PCIe address is labelled for both front-end and back-end connections, only front-end traffic flows through this interface.