Disabling of Host Learning on L2 Overlay Networks
Starting with NetVisor version 7.1.0, NetVisor allows you to disable host learning when the VLANs and/or VXLANs are used for Layer 2 switching. This helps in ensuring that the Layer 3 table entries are not getting bloated and cross the 1.2M entries threshold. That is, you can disable the address resolution protocol (ARP) and neighbor discover (ND) learning for specified VLANs when the traffic is L2 switched. Additionally, configuring this feature avoids unnecessary CPU processing and activating of L3 entries.
You can configure the VLANs and IP address types for which you want to disable the host learning. Subsequently, when nvOSd gets ARP/ND packets matching the configured VLANs, then, those packets do not get processed.
The following four CLI commands are introduced to configure and verify the disable host learning feature in NetVisor version 7.1.0:
CLI (network-admin@switch) > host-learning-disable-settings-
|
host-learning-disable-settings-add-vlans |
Use this command to add VLANs to host learning disabled vlan-list. |
|
host-learning-disable-settings-modify |
Use this command to modify host learning disable settings for the previously configured VLANs. When you use this command, the previously configured VLANs are overwritten with the new VLAN list. |
|
host-learning-disable-settings-remove-vlans |
Use this command to remove all or some of the previously configured VLANs from host learning disabled vlan-list. |
|
host-learning-disable-settings-show |
Use this command to display host learning disable settings for the configured VLANs. |
Below is an example configuration to disable the host learning on VLANs. To disable the host learning for a specified VLAN (here vlan 10 and 120) and IP address type, use the command:
CLI (network-admin@switch) > host-learning-disable-settings-add-vlans vlans 10,120
To view the details, use the command:
CLI (network-admin@switch) > host-learning-disable-settings-show
switch: switch
vlans: 10,120
address-type: IPv4-IPv6
To modify the VLAN list or IP address type, use the command:
CLI (network-admin@switch) > host-learning-disable-settings-modify
|
host-learning-disable-settings-modify |
Use this command to modify host learning disable settings for the previously configured VLANs. When you use this command, the previously configured VLANs are overwritten with the new VLAN list. |
|
vlans vlan-list |
Specify the VLAN IDs or range for which host learning is disabled. |
|
address-type IPv4|IPv6|IPv4-IPv6 (optional) |
Specify the IP address type for which host learning is disabled. The default type is IPv4-IPv6. |
For example, to modify the VLAN to 200 and 240, use the command:
CLI (network-admin@switch) > host-learning-disable-settings-modify vlans 200,240 address-type IPv4-IPv6
CLI (network-admin@switch) > host-learning-disable-settings-show
switch: switch
vlans: 200,240
address-type: IPv4-IPv6
To remove the configured VLAN (s), use the command:
CLI (network-admin@swiitch) > host-learning-disable-settings-remove-vlans vlans 240
CLI (network-admin@switch) > host-learning-disable-settings-show
switch: switch
vlans: 200
address-type: IPv4-IPv6