Overview
By default, data connections between client devices and VAST Cluster use Layer 2. Layer 2 (Data Link Layer) handles communication within the same network segment using MAC addresses, focusing on local data transfer between devices, such as on a switch.
Alternatively, you can enable Layer 3 for these communications. Layer 3 facilitates communication between different networks using IP addresses. It determines the best path for data across multiple networks, typically through routers. Border Gateway Protocol (BGP), a key Layer 3 protocol, is used for routing between different autonomous systems (ASes) on the internet, helping manage data paths based on network policies and availability. To use this option, switches must be L3 enabled.
Layer 2 should be used if clients connect to the cluster locally using simple networks. Layer 3, with BGP, should be used if clients are connecting across complex networks and customer switches support BGP.
Numbered and Unnumbered BGP Configurations
You can configure BGP to be numbered or unnumbered. In numbered BGP, CNodes and routers (also referred to as peers) in the network use assigned IP addresses for BGP communication. These are configured on the cluster manager.
Limitations
Review these architectural and operational limitations before deploying L3 networking across your virtual IP pools:
After enabling L3 access for a virtual IP pool, it cannot be disabled.
L3 access is not supported on virtual IP pools for which CNode port affinity is configured.
L3 access is not supported on virtual IP pools that include more than one range of virtual IPs.
L3 networking is not supported on IB clusters.
L3 networking is not supported for VAST on Cloud.
MD5 authentication is not supported.
When using numbered BGP, each CNode can only be involved in one BGP configuration. To learn which CNodes are currently used in specific BGP configurations, navigate to the Network Access -> Virtual IP Pools page to view the active mapping metrics.
You cannot revert an L3-configured cluster to L2 through VMS. If you need to revert, contact VAST Support.
Configuring BGP for Layer 3 Connectivity
Follow these steps to configure BGP for Layer 3 connectivity. A single BGP configuration applies to the entire cluster environment.
Navigate to the Network Access page and select the BGP Configurations tab.
Click Create BGP.
In the General tab, enter the following parameters:
Name
The name of the BGP configuration as it appears in the configuration grid table.
VAST ASN
The ASN presented by cluster CNodes to upstream routing devices.
Method
Select whether numbered or unnumbered BGP is used.
External ASN
The ASN expected to be presented to CNodes by upstream routers. Select one of these options:
Use any: Permits any value to be parsed dynamically.
Set manually: Allows input of a specific static ASN value.
If Numbered BGP is specified for the configuration method, open the VIPs tab to enter address ranges for your peer-to-peer connections.
For each address range, do the following:
Rack
Select the target rack structure configuration from the list.
IP Range
Enter an even-numbered range of contiguous IP addresses. The range must be exactly twice the number of target CNodes, allocating one address to each internal port and one to each switch port.
The range can be entered as individual addresses (example:
10.10.0.1, 10.10.0.2), an absolute range (example:10.10.0.1-40), or a standard CIDR block mask (example:10.10.0.1/28).BGP Peer
Enter the interface IP address of the upstream BGP peer L3 switch. This address is shared by all CNodes in the rack.
Click Add rack and IP range to list.
Select how the address range is divided between the CNodes and the switch ports:
Even - Even-numbered addresses map to CNode interfaces; odd addresses map to switch ports.
Odd - Odd-numbered addresses map to CNode interfaces; even addresses map to switch ports.
Click Create.
In the Network Access navigation page, choose Virtual IP Pools.
Click Create Virtual IP Pool and complete configuration steps outlined inside Managing Virtual IP Pools.
In the Advanced settings grouping, toggle the Enable L3 configuration control to an active state.
Select the newly defined BGP configuration block item from the drop-down menu selection list.
Click Create or click Update to commit your modifications.
From the primary Network Access page menu context layout, select DNS.
Right-click your existing active DNS configuration element profile, and then click Edit.
Within the context panel of the L3 configuration section, toggle Enable L3 to its active state position.
Select your corresponding active BGP configuration option routing rule from the list.
Click Update to apply modifications globally.