Configure Scylla Networking with Multiple NIC/IP Combinations

There are many ways to configure IP addresses in scylla.yaml. Setting the IP addresses incorrectly, can yield less than optimal results. This article focuses on confguring the addresses which are vital to network communication.

This article contains examples of the different ways to configure networking in scylla.yaml. The entire scope for address configuration is in the Admin guide.

As these values depend on a particular network configuration in your setup there are a few ways to configure the above these four address parameters. In the examples below, we will provide instructions for the most common use cases (all in the resolution of a single Scylla node).

1 NIC, 1 IP

This is the case where a Scylla cluster is meant to operate in a single subnet with a single address space (no “public/internal IP”s).

In this case:

  • IP = node’s IP address
listen_address: IP
rpc_address: IP
broadcast_address: not set
broadcast_rpc_address: not set
endpoint_snitch: no restrictions

1 NIC, 2 IPs

This is the case where you are using Public and Internal IP addresses. AWS instances with public IP addresses is a classic example of this configuration.

In this case:

  • IPp = the node’s public IP address
  • IPi = the node’s internal IP address

IPi is the IP configured to the same IP as the NIC (from the OS perspective) and when running the command ifconfig <iface> the output displays this IP address.

listen_address: IPi
rpc_address: IPi
broadcast_address: IPp
broadcast_rpc_address: IPp
endpoint_snitch: GossipintPropertyFileSnitch with prefer_local=true | any of Ec2xxxSnitch snitches.

2 NICs, 2 IPs

This is the case where a user wants CQL requests or responses to be sent via one subnet (net1) and inter-node communication to go over another subnet (net2).

In this case:

  • IP1 = node’s IP in net1 subnet
  • IP2 = node’s IP in net2 subnet
listen_address: IP2
rpc_address: IP1
broadcast_address: not set
broadcast_rpc_address: not set
endpoint_snitch: no restrictions

Additional References

Administration Guide - User guide for Scylla Administration