Internode network requirements

The following table lists the internode network requirements in VSP One SDS Block.

Item	Requirement	Remarks
Basic configuration	Configure as an L2 network.
Connectivity	Communication between storage nodes should be possible.	For details about the TCP/UDP port numbers to be used, see `TCP/UDP port numbers required for communication`.
Bandwidth	At least 1-Gbps bandwidth is required.	The recommended bandwidth is 10 Gbps or more. If VeryHigh is set for AsyncProcessingResourceUsageRate in the VSSB configuration file, bandwidth of at least 25 Gbps is required. The recommended value for the MTU size (InterNodeNWMTUSize) to be set in VSP One SDS Block is 9000 bytes. When you set the MTU size on network equipment, set a size that allows packets of the MTU size (InterNodeNWMTUSize) set in VSP One SDS Block to be transferred without being divided. Note that the maximum frame size set on network switches sometimes must be larger than the MTU size set for InterNodeNWMTUSize in VSP One SDS Block in consideration of the size of the header added in Layer 2. For details, see the documentation for the network switches in use. The same bandwidth (link speed) of the internode port must be set on all storage nodes.
Delay	The average round trip time between storage nodes should be 1 millisecond or less.	You can verify this with the RTT value displayed after running the ping command.
Availability	When the network is redundant, the convergence time from a failure should be less than a second.	Make the network redundant so that it has no single point of failure (SPOF) that could disable communication in multiple storage nodes. An SPOF could cause a single network appliance failure or other link failure to stop the VSP One SDS Block cluster. If you enable STP (Spanning Tree Protocol), enable the PortFast function on the network switch port connected to the storage node. For how to set the PortFast function, see the documentation of the network switch in use. Set the link flap prevention function for the network switch connected to the storage node. For the setting procedure, see the documentation of the network switch in use.
Security	Configure as a dedicated closed network. Do not connect any other than connection between the internode network port on the storage node of the VSP One SDS Block and network monitoring systems, and temporary connection such as investigating terminal for fault isolation.	If you are temporarily connecting to the internode network, such as an investigating terminal for fault isolation, be sure to disconnect it when the fault isolation is complete.
Monitoring	Equipped with a network monitoring system independent of VSP One SDS Block to detect network failures and performance degradation (switch failures, link failures, increased delays, increased packet loss, connections at unexpected link speed operating values and duplex operating values, and others.), and configure it so that the cause can be identified.	If the internode network is not provided with a monitoring system, it might be impossible to troubleshoot network failures or performance degradation. The number of TCP retransmissions for the internode network is monitored on storage nodes and used to detect network failure and performance degradation (or to identify their causes). When TCP retransmission continues for approximately 30 to 60 minutes, event log KARS08330-W, which indicates that TCP retransmission has occurred, is output.
Expandability	Determine a network topology and allocate IP addresses in consideration of the possibility that storage nodes might be added in the future.