Configuring Link Scan Mode

The link scan feature in NetVisor OS detects physical link state changes. NetVisor OS version 6.0.0 (and later) supports interrupt-based link state change detection, in addition to the software-based link scan mode available in the previous versions. The software-based link scan mode performs state polling to detect changes at regular configurable intervals. When the link scan mode is set to hardware, on the other hand, the software uses the interrupt infrastructure to provide an improved detection mechanism for link state changes.

You can configure the link scan mode and interval by using the system-settings-modify command:


Use this command to modify system settings.

linkscan-interval 10000..1000000

Specify the linkscan interval as a value between 10000 μs and 1000000 μs. The default value is 150000 μs.

Note: This parameter is not applicable when the link scan mode is hardware.

linkscan-mode software|hardware

Specify the linkscan mode as hardware or software. Software linkscan mode is enabled by default.

Note: Arista recommends software linkscan mode.

For example, to enable interrupt-based link state change detection, use the command:

CLI (network-admin@switch) > system-settings-modify linkscan-mode hardware

To view the current configuration, use the command:

CLI (network-admin@switch) > system-settings-show format linkscan-mode

linkscan-mode: hardware

To modify the link scan interval used in software-based mode to 100,000  μs, enter the command:

CLI (network-admin@switch) > system-settings-modify linkscan-interval 100000

To view the details, enter the command:

CLI (network-admin@switch) > system-settings-show

switch:                          Leaf1

optimize-arps:                   off

lldp:                            on

policy-based-routing:            off

optimize-nd:                     off

reactivate-mac:                  on

reactivate-vxlan-tunnel-mac:     on

manage-unknown-unicast:          off

manage-broadcast:                off

auto-trunk:                      on

auto-host-bundle:                off

cluster-active-active-routing:   on

fast-route-download:             off

fast-interface-lookup:           on

routing-over-vlags:              off

source-mac-miss:                 copy-to-cpu

igmp-snoop:                      use-l3

vle-tracking-timeout:            3

pfc-buffer-limit:                40%

cosq-weight-auto:                off

port-cos-drop-stats-interval(s): disable

lossless-mode:                   off

snoop-query-stagger:             no-stagger-queries

host-refresh:                    off

proxy-conn-retry:                on

proxy-conn-max-retry:            3

proxy-conn-retry-interval:       500

manage-l2-uuc-drop:              on

xcvr-link-debug:                 disable

fastpath-bfd:                    off

linkscan-interval:               100000

linkscan-mode:                   hardware

single-pass-flood:               off

Note: To avoid flaps, the link scan mode must match on both the switch ports connected by a link.