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• Reserved Range: Two configurable reserved ranges in DHCP are at the upper and lower extremities of the subnet. These reserved ranges are special IP addresses for routers, network devices, etc., and are used for any servers that require direct participation in the Swarm cluster (Elasticsearch nodes, Content Gateway instances, etc.). None of these ranges has any default size., and at least one MUST must be specified during DHCP initialization.One of the reserved ranges is set aside when the site needs a static IP allocation for Swarm nodes.

• Transient Pool: The dynamic Storage Pool: IP addresses that are used during the early stages of booting Swarm for Swarm storage nodes. This is configured as a percentage of the overall DHCP-managed range.Storage Pool: IP addresses that are used for Swarm storage nodes. If the number of storage nodes exceeds this pool, the transient pool is also used for the excess nodes. This is a remainder of the DHCP-managed range, which is not allocated to the transient poolpool is used to provide temporary IP addresses when storage nodes are first booting, and any static IP addresses are also within this range.
  See Configuring Swarm for Static IPs with Swarm Cluster Services (SCS) for details about static IP address configuration.

The DCHP server utilizes the following breakdown of the subnet:

Subnet Layout:

  |                     |                    |                      |                     |
  | <- reserve lower -> | <--- DHCP/storage pool -> | <- transient pool -> | <- reserve upper -> |
  |                     |                             |                     |
subnet   |                     | subnet                  | <--------- DHCP Managed Range ----------> |                 broadcast
address  

Range Sizing

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The Swarm-facing network interface on the SCS server acts as a contact point for all SCS services for the cluster (logging, PXE booting, NTP, etc.) and as a default network gateway. Choose Select an appropriate static IP address cautiously for this interface. The IP address is often at the bottom of the lower range (but it is not required).

However, the IP address must be within either the upper or lower range but ; placing it outside of these ranges conflicts may conflict with the IP allocation.

Other Swarm Services

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If the Swarm deployment requires storage nodes to be given static IP addresses, then one of the reserved ranges is set aside for these IP addressessee Configuring Swarm for Static IPs with Swarm Cluster Services (SCS).

Other IP Addresses

Sometimes, the organizational policy represents that other services have access to the network while the Swarm network is private. The static IP addresses are provided to these services in either the lower or upper reserved ranges.

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If the MTU needs to be configured for the internal Swarm network, see https://perifery.atlassian.net/wiki/spaces/public/pages/1223491667/SCS+Administration#Swarm-(Internal)-Network-MTU.

Examples

Following two scenarios of the Network Planning assume the default transient pool allocation is 50%. The pool size and the size of the upper and lower reserved ranges are configurable.

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Small Network (/24)

Implications

• 222 Storage nodes (sum size of transient and storage pool) on the network

• Up to 111 222 chassis can PXE boot simultaneously (determined by the transient pool size)

Large Network (/16)

Implications

• 65,000 Storage nodes (sum size of transient pool and storage pool) on the network

• Up to 3265,500 000 chassis can PXE boot simultaneously (determined by the transient pool size)

Podman Network Ranges

Podman sets up an internal network for containers to talk to each other. The range 10.88.0.0/16 is used internally for the podman network on SCS nodes and is reserved for container communication. If this IP range (or an overlapping IP address range) is used for normal network communications, conflicts occur and network traffic becomes unpredictable. Verify the IP range is not used outside of Swarm.

External Network Connectivity

Storage Cluster Connectivity

When the storage cluster needs to communicate outside of its network (replication feeds, for example), the SCS machine provides network address translation (NAT) to keep the internal network better shielded from external access.

HTTP Proxying

SCS does not support use of environment variables that govern the use of HTTP proxies (HTTP_PROXY, HTTPS_PROXY, etc.). If these variables are set on SCS, network communication will be disrupted.