Interface Configuration and Management
This section discusses how to configure the interfaces on the switch.
Cumulus Linux (including NVUE) uses ifupdown2 to manage network interfaces, which is a new implementation of the Debian network interface manager ifupdown.
Bring an Interface Up or Down
An interface status can be in an:
- Administrative state, where you configure the interface to be up or down. The administrative state reflects the intended configuration set by an administrator or management system. It indicates whether the interface is meant to be enabled or disabled.
- Operational state, which reflects the current operational status of an interface. The operational state reflects the actual current status of the interface, taking into account physical and logical conditions.
The carrier state is the lower layer state of an interface. For a switch port, the carrier state represents if the switch port is enabled at the ASIC level and a cable connects successfully. For a virtual interface, the carrier state involves the operational state of lower-level interfaces. For example, for a VLAN interface, the carrier state depends on the underlying bridge device operational state.
The operational state always depends on administrative state and carrier state; the operational state is a function of the administrative state, carrier state and other link states.
To configure and bring an interface up administratively, use the nv set interface command:
cumulus@switch:~$ nv set interface swp1
cumulus@switch:~$ nv config apply
After you bring up an interface, you can bring it down administratively by changing the link state to down:
cumulus@switch:~$ nv set interface swp1 link state down
cumulus@switch:~$ nv config apply
To bring the interface back up, change the link state back to up:
cumulus@switch:~$ nv set interface swp1 link state up
cumulus@switch:~$ nv config apply
To remove an interface from the configuration entirely, use the nv unset interface command:
cumulus@switch:~$ nv unset interface swp1
cumulus@switch:~$ nv config apply
NVUE applies only current configuration changes instead of processing the entire /etc/network/interfaces file.
To configure and bring an interface up administratively, edit the /etc/network/interfaces file to add the interface stanza, then run the ifreload -a command:
cumulus@switch:~$ sudo nano /etc/network/interfaces
auto lo
iface lo inet loopback
address 10.10.10.1/32
auto mgmt
iface mgmt
address 127.0.0.1/8
address ::1/128
vrf-table auto
auto eth0
iface eth0 inet dhcp
ip-forward off
ip6-forward off
vrf mgmt
auto swp1
iface swp1
...
To bring an interface down administratively after you configure it, add link-down yes to the interface stanza in the /etc/network/interfaces file, then run ifreload -a:
auto swp1
iface swp1
link-down yes
If you configure an interface in the /etc/network/interfaces file, you can bring it down administratively with the ifdown swp1 command, then bring the interface back up with the ifup swp1 command. These changes do not persist after a reboot. After a reboot, the configuration present in /etc/network/interfaces takes effect.
- By default, the
ifupdownandifupcommands are quiet. Use the verbose option (-v) to show commands as they execute when you bring an interface down or up. - For configurations at scale, you can run the
ifreload -a --diffcommand to apply only current configuration changes instead of processing the entire/etc/network/interfacesfile.
To remove an interface from the configuration entirely, remove the interface stanza from the /etc/network/interfaces file, then run the ifreload -a command.
For additional information on interface administrative state and physical state, refer to this knowledge base article.
Loopback Interface
Cumulus Linux has a preconfigured loopback interface. When the switch boots up, the loopback interface called lo is up and assigned an IP address of 127.0.0.1.
The loopback interface lo must always exist on the switch and must always be up.
To configure an IP address for the loopback interface:
cumulus@switch:~$ nv set interface lo ip address 10.10.10.1/32
cumulus@switch:~$ nv config apply
Edit the /etc/network/interfaces file to add an address line:
auto lo
iface lo inet loopback
address 10.10.10.1/32
You can configure multiple IP addresses for the loopback interface.
Subinterfaces
On Linux, an interface is a network device that can be either physical, (for example, swp1) or virtual (for example, vlan100). A VLAN subinterface is a VLAN device on an interface, and the VLAN ID appends to the parent interface using dot (.) VLAN notation. For example, a VLAN with ID 100 that is a subinterface of swp1 is swp1.100. The dot VLAN notation for a VLAN device name is a standard way to specify a VLAN device on Linux.
A VLAN subinterface only receives traffic tagged for that VLAN; therefore, swp1.100 only receives packets that have a VLAN 100 tag on switch port swp1. Any packets that transmit from swp1.100 have a VLAN 100 tag.
The following example configures a routed subinterface on swp1 in VLAN 100:
cumulus@switch:~$ nv set interface swp1.100 ip address 192.168.100.1/24
cumulus@switch:~$ nv config apply
Edit the /etc/network/interfaces file, then run ifreload -a:
cumulus@switch:~$ sudo nano /etc/network/interfaces
...
auto swp1.100
iface swp1.100
address 192.168.100.1/24
cumulus@switch:~$ sudo ifreload -a
- If you are using a VLAN subinterface, do not add that VLAN under the bridge stanza.
- You cannot use NVUE commands to create a routed subinterface for VLAN 1.
Interface IP Addresses
You can specify both IPv4 and IPv6 addresses for the same interface.
For IPv6 addresses:
- You can create or modify the IP address for an interface using either
::or0:0:0notation. For example, both 2620:149:43:c109:0:0:0:5 and 2001:DB8::1/126 are valid. - Cumulus Linux assigns the IPv6 address with all zeroes in the interface identifier (2001:DB8::/126) for each subnet; connected hosts cannot use this address.
- You can use Stateless Address Auto-Configuration (SLAAC) to configure an IPv6 address for an interface automatically.
The following example commands configure three IP addresses for swp1; two IPv4 addresses and one IPv6 address.
cumulus@switch:~$ nv set interface swp1 ip address 10.0.0.1/30
cumulus@switch:~$ nv set interface swp1 ip address 10.0.0.2/30
cumulus@switch:~$ nv set interface swp1 ip address 2001:DB8::1/126
cumulus@switch:~$ nv config apply
To show the MAC address for an interface, run the nv show interface <interface-id> link command.
In the /etc/network/interfaces file, list all IP addresses under the iface section.
auto swp1
iface swp1
address 10.0.0.1/30
address 10.0.0.2/30
address 2001:DB8::1/126
The address method and address family are not mandatory; they default to inet/inet6 and static. However, you must specify inet/inet6 when you are creating DHCP or loopback interfaces.
auto lo
iface lo inet loopback
To make non-persistent changes to interfaces at runtime, use ip addr add:
cumulus@switch:~$ sudo ip addr add 10.0.0.1/30 dev swp1
cumulus@switch:~$ sudo ip addr add 2001:DB8::1/126 dev swp1
To remove an address from an interface, use ip addr del:
cumulus@switch:~$ sudo ip addr del 10.0.0.1/30 dev swp1
cumulus@switch:~$ sudo ip addr del 2001:DB8::1/126 dev swp1
Interface MAC Addresses
You can configure a MAC address for an interface with the nv set interface <interface-id> link mac-address <mac-address> command.
The following command configures swp1 with MAC address 00:02:00:00:00:05:
cumulus@switch:~$ nv set interface swp1 link mac-address 00:02:00:00:00:05
cumulus@switch:~$ nv config apply
The following command configures vlan10 with MAC address 00:00:5E:00:01:00:
cumulus@switch:~$ nv set interface vlan10 link mac-address 00:00:5E:00:01:00
cumulus@switch:~$ nv config apply
To unset the MAC address for an interface, run the nv unset interface <interface-id> link mac-address command. This command resets the MAC address to the system assigned address.
cumulus@switch:~$ nv unset interface swp1 link mac-address
cumulus@switch:~$ nv config apply
In the /etc/network/interfaces file, add a MAC address for the interface in the interface stanza, then run ifreload -a.
The following example configures swp1 with MAC address 00:02:00:00:00:05:
cumulus@switch:~$ sudo nano /etc/network/interfaces
...
auto swp1
iface swp1
address 10.0.0.2/24
hwaddress 00:02:00:00:00:05
...
cumulus@switch:~$ sudo ifreload -a
The following example configures vlan10 with MAC address 00:00:5E:00:01:00:
cumulus@switch:~$ sudo nano /etc/network/interfaces
...
auto vlan10
iface vlan10
address 10.1.10.5/24
hwaddress 00:00:5E:00:01:00
cumulus@switch:~$ sudo ifreload -a
To unset the MAC address for an interface, remove the mac address from the interface stanza, then run the sudo ifreload -a command.
Interface Descriptions
You can add a description (alias) to an interface.
Interface descriptions also appear in the SNMP OID IF-MIB::ifAlias
- Interface descriptions can have a maximum of 255 characters.
- Avoid using apostrophes or non-ASCII characters. Cumulus Linux does not parse these characters.
The following example commands create the description hypervisor_port_1 for swp1:
cumulus@switch:~$ nv set interface swp1 description hypervisor_port_1
cumulus@switch:~$ nv config apply
In the /etc/network/interfaces file, add a description using the alias keyword:
cumulus@switch:~$ sudo nano /etc/network/interfaces
auto swp1
iface swp1
alias swp1 hypervisor_port_1
Interface Commands
You can specify user commands for an interface that run at pre-up, up, post-up, pre-down, down, and post-down.
You can add any valid command in the sequence to bring an interface up or down; however, limit the scope to network-related commands associated with the particular interface. For example, it does not make sense to install a Debian package on ifup of swp1, even though it is technically possible. See man interfaces for more details.
The following examples adds a command to an interface to enable proxy ARP:
cumulus@switch:~$ sudo nano /etc/network/interfaces
auto swp1
iface swp1
address 12.0.0.1/30
post-up echo 1 > /proc/sys/net/ipv4/conf/swp1/proxy_arp
If your post-up command also starts, restarts, or reloads any systemd service, you must use the --no-block option with systemctl. Otherwise, that service or even the switch itself might hang after starting or restarting. For example, to restart the dhcrelay service after bringing up a VLAN, the /etc network/interfaces configuration looks like this:
auto bridge.100
iface bridge.100
post-up systemctl --no-block restart dhcrelay.service
Port Ranges
To specify port ranges in commands:
Use commas to separate different port ranges.
The following example configures the default bridge br_default with swp1 through swp46 and swp10 through swp12:
cumulus@switch:~$ nv set interface swp1-4,6,10-12 bridge domain br_default
cumulus@switch:~$ nv config apply
The following example sets all subinterfaces of swp1s within the range 1-4:
cumulus@switch:~$ nv set interface swp1s1-4
cumulus@switch:~$ nv config apply
The following example sets all interfaces within the swp range 1 through 64 and their subinterface range 1 through 3:
cumulus@switch:~$ nv set interface swp1-64s1-3
cumulus@switch:~$ nv config apply
Use the glob keyword to specify bridge ports and bond slaves:
auto br0
iface br0
bridge-ports glob swp1-6.100
auto br1
iface br1
bridge-ports glob swp7-9.100 swp11.100 glob swp15-18.100
Fast Linkup
Cumulus Linux supports fast linkup on interfaces on NVIDIA Spectrum1 switches. Fast linkup enables you to bring up ports with cards that require links to come up fast, such as certain 100G optical network interface cards.
You must configure both sides of the connection with the same speed and FEC settings.
cumulus@switch:~$ nv set interface swp1 link fast-linkup enabled
cumulus@switch:~$ nv config apply
Edit the /etc/cumulus/switchd.conf file and add the interface.<interface-id>.enable_media_depended_linkup_flow=TRUE and interface.<interface-id>.enable_port_short_tuning=TRUE settings for the interfaces on which you want to enable fast linkup. The following example enables fast linkup on swp1:
cumulus@switch:~$ sudo nano /etc/cumulus/switchd.conf
...
interface.swp1.enable_media_depended_linkup_flow=TRUE
interface.swp1.enable_short_tuning=TRUE
Reload switchd with the sudo systemctl reload switchd.service command.
Link Flap Protection
Cumulus Linux enables link flap detection by default. Link flap detection triggers when there are five link flaps within ten seconds, at which point the interface goes into a protodown state and shows linkflap as the reason. The switchd service also shows a log message similar to the following:
2023-02-10T17:53:21.264621+00:00 cumulus switchd[10109]: sync_port.c:2263 ERR swp2 link flapped more than 3 times in the last 60 seconds, setting protodown
To show interfaces with the protodown flag, run the NVUE nv show interface status command or the Linux ip link command. To check a specific interface, run the nv show interface <interface-id> link command.
cumulus@switch:~$ nv show interface status
Interface Admin Status Oper Status Protodown Protodown Reason
-------------- ------------ ----------- --------- ----------------
BLUE up up disabled
RED up up disabled
bond1 up up disabled
bond2 up up disabled
bond3 up up disabled
br_default up up disabled
eth0 up up disabled
lo up unknown disabled
mgmt up up disabled
peerlink up up disabled
peerlink.4094 up up disabled
swp1 up up disabled
swp2 up up disabled
swp3 up down enabled linkflap
swp4 down down disabled
swp5 down down disabled
swp6 down down disabled
swp7 down down disabled
swp8 down down disabled
swp9 down down disabled
swp10 down down disabled
...
cumulus@switch:~$ ip link
...
37: swp3: <NO-CARRIER,BROADCAST,MULTICAST,SLAVE,UP> mtu 9178 qdisc pfifo_fast master bond131 state DOWN mode DEFAULT group default qlen 1000
link/ether 1c:34:da:ba:bb:2a brd ff:ff:ff:ff:ff:ff protodown on protodown_reason <linkflap>
...
cumulus@switch:~$ nv show interface swp3 link
operational applied
----------------------- ----------------- -------
admin-status up
oper-status up
oper-status-last-change Unknown
protodown enabled
auto-negotiate disabled enabled
duplex full full
speed 1G auto
mac-address 48:b0:2d:63:34:55
fec auto
mtu 9000 9216
fast-linkup disabled
[breakout]
state up up
flap-protection
enable on
stats
in-bytes 52.86 MB
in-pkts 440743
in-drops 0
in-errors 0
out-bytes 53.00 MB
out-pkts 444066
out-drops 0
out-errors 0
carrier-transitions 4
carrier-up-count 2
carrier-down-count 2
cumulus@switch:~$ nv show interface swp3 link protodown-reason
operational
-----------
linkflap
Clear the Interface Protodown State and Reason
To clear the protodown state and the reason:
cumulus@switch:~$ nv action clear interface swp1 link flap-protection violation
After a few seconds the port state returns to up. Run the nv show <interface-id> link state command to verify that the interface is no longer in a protodown state and that the reason clears:
cumulus@switch:~$ nv show interface swp1 link state
operational applied
----------- -------
up up
To clear all the interfaces from a protodown state, run the nv action clear system link flap-protection violation.
The ifdown and ifup commands do not clear the protodown state. You must clear the protodown state and the reason manually using the sudo ip link set <interface-id> protodown_reason linkflap off and sudo ip link set <interface-id> protodown off commands.
cumulus@switch:~$ sudo ip link set swp2 protodown_reason linkflap off
cumulus@switch:~$ sudo ip link set swp2 protodown off
After a few seconds, the port state returns to UP. To verify that the interface is no longer in a protodown state and that the reason clears, run the ip link show <interface-id> command:
cumulus@switch:~$ ip link show swp2
37: swp2: <NO-CARRIER,BROADCAST,MULTICAST,SLAVE,UP> mtu 9178 qdisc pfifo_fast master bond131 state UP mode DEFAULT group default qlen 1000
link/ether 1c:34:da:ba:bb:2a brd ff:ff:ff:ff:ff:ff
Change Link Flap Protection Settings
You can change the following link flap protection settings:
- The duration in seconds during which a link must flap the number of times set in the link flap threshold before link flap protection triggers. You can specify a value between 0 (disabled) and 300. The default setting is 10.
- The number of times the link can flap within the link flap window before link flap protection triggers. You can specify a value between 0 (disabled) and 30. The default setting is 5.
The following example configures the link flap duration to 30 and the number of times the link must flap to 8.
cumulus@switch:~$ nv set system link flap-protection interval 30
cumulus@switch:~$ nv set system link flap-protection threshold 8
cumulus@switch:~$ nv config apply
Edit the /etc/cumulus/switchd.conf file to change the link_flap_window and link_flap_threshold settings.
cumulus@switch:~$ sudo nano /etc/cumulus/switchd.conf
...
link_flap_window = 30
link_flap_threshold = 8
...
After you change the link flap settings, you must restart switchd with the sudo systemctl restart switchd.service command.
Disable Link Flap Protection
To disable link flap protection:
cumulus@switch:~$ nv set interface swp1 link flap-protection state disabled
cumulus@switch:~$ nv config apply
Edit the /etc/cumulus/switchd.conf file, and set the link_flap_window and link_flap_threshold parameters to 0 (zero).
cumulus@switch:~$ sudo nano /etc/cumulus/switchd.conf
...
link_flap_window = 0
link_flap_threshold = 0
Show Link Flap Protection Configuration
To show the link flap protection time interval and threshold settings:
cumulus@switch:~$ nv show system link flap-protection
operational applied
--------- ----------- -------
threshold 5
interval 10
To show if link flap protection is on an interface, run the nv show interface <interface-id> link flap-protection command:
cumulus@switch:~$ nv show interface swp1 link flap-protection
applied
------ -------
state disabled
Link Debounce Timers
A flapping port can cause network instability and disruption as layer 2 and layer 3 protocols are constantly forced to reconverge and rebuild the topology with every port status change. If flapping occurs at short intervals, it can also cause a spike in CPU utilization. To enhance the stability of Ethernet port link state transitions and mitigate network disruptions resulting from port flapping, Cumulus Linux provides link debounce hold timers for link state transitions. The switch waits until the port status is stable for a configured period before notifying layer 2 and layer 3 protocols about the status change (up or down).
When a link transitions up or down, the debounce timer starts. The switch reports the link change only after the timer expires, and the link remains in that state. If the link toggles back before the timer expires, the switch ignores the event and does not report any state change.
- You can configure link debounce timers on physical switch ports only.
- The maximum debounce timer values are limited by SDK capabilities (5000ms).
- NVIDIA recommends that you use identical or similar debounce timer values on both ends of the link.
- Link debounce and link flap protection are complementary features that work at different time scales. Link debounce filters transient noise and micro-interruptions whereas link flap protection detects excessive legitimate state transitions and protects the system by placing the interface into a protodown state. If you configure both features, set the link flap protection interval to be significantly larger than the debounce timers to ensure proper coordination.
To configure the link debounce timers, run the commands below. The hold timers allow a value between 0 and 5000. The default value is 10 milliseconds. A value of 0 disables the timer.
Run the nv set interface <interface> link debounce up and nv set interface <interface> link debounce down commands.
If you configure one direction only, the other direction uses the default value of 10 milliseconds.
cumulus@switch:~$ nv set interface swp1 link debounce up 2000
cumulus@switch:~$ nv set interface swp1 link debounce down 1000
cumulus@switch:~$ nv config apply
To unset the link debounce hold timers, run the nv unset interface <interface> link debounce command.
Edit the /etc/cumulus/switchd.d/link.conf file to edit the interface.swp61s0.link_debounce.up_delay and interface.swp61s0.link_debounce.down_delay options, then reload switchd:
cumulus@switch:~$ sudo nano /etc/cumulus/switchd.d/link.conf
interface.swp1.link_debounce.up_delay = 2000
interface.swp1.link_debounce.down_delay = 1000
cumulus@switch:~$ sudo systemctl reload switchd.service
To show the link transitions for an interface, run the nv show interface <interface-id> link debounce command.
cumulus@switch:~$ nv show interface swp1 link debounce
operational applied
---- ----------- -------
up 200 200
down 150 150
To show link debounce statistics for an interface, run the nv show interface <interface-id> counters link debounce command.
cumulus@switch:~$ nv show interface swp1 counters link debounce
operational
-------------------- -----------
ignored-down-events 0
ignored-up-events 0
received-up-events 2
received-down-events 1
timer-cancellations 0
timer-expirations 3
To show the link debounce statistics for all interfaces, run the nv show interface debounce-counters command:
cumulus@switch:~$ nv show interface debounce-counters
Interface ignored-up ignored-down received-up received-down timer-cancel timer-expire
--------- ---------- ------------ ----------- ------------- ------------ ------------
swp1 10 8 23 22 18 45
swp2 5 3 15 14 8 22
swp3 0 0 2 2 0 4
To clear link debounce statistics for an interface, run the nv action clear interface <interface-id> counters link debounce command:
cumulus@switch:~$ nv action clear interface swp1 counters link debounce
To clear link debounce statistics for all interfaces, run the nv action clear interface debounce-counters command:
cumulus@switch:~$ nv action clear interface debounce-counters
Tx Squelch Control
Tx squelch control is a Beta feature.
Tx squelch control is a PHY‑level feature that controls if the local port continues transmitting when the remote side is logically down (for example, when the remote side is in a fault state or needs to restart auto-negotiation).
- Switches with Spectrum-4 and later support Tx squelch control.
- Cumulus Linux supports Tx squelch control on physical ports only (including breakout ports).
- Enabling or disabling Tx squelch control is disruptive on admin UP ports. The switch performs a port admin‑status down, then port admin‑status up for the changes to take effect.
- Enabling or disabling Tx squelch control is not disruptive on admin DOWN ports. When you enable or disable Tx squelch control on an admin DOWN port, the new setting becomes effective the next time the port is admin UP.
To enable Tx squelch control, run the nv set interface <interface> link tx-squelch enabled command. The default setting is auto, which enables the switch to decide the correct configuration.
cumulus@switch:~$ nv set interface swp1 link tx-squelch enabled
cumulus@switch:~$ nv config apply
To disable Tx squelch control, run the nv set interface <interface> link tx-squelch disabled command.
To show if Tx squelch control is enabled, run the nv show interface <interface> link command:
cumulus@switch:~$ nv show interface swp1 link
operational applied
----------------------- ----------------------- -------
admin-status up
oper-status up
oper-status-last-change 2024/10/11 19:12:16.339
protodown disabled
auto-negotiate disabled enabled
duplex full full
speed 1G auto
mac-address 48:b0:2d:fa:a1:14
fec auto
mtu 9000 9216
fast-linkup disabled
tx-squelch enabled auto
To enable Tx squelch control, edit the /etc/cumulus/switchd.conf file to set the interface.<interface-id>.tx_squelch parameter to enabled, then reload switchd.
cumulus@switch:~$ sudo nano /etc/cumulus/switchd.conf
...
interface.swp1.tx_squelch = enabled
cumulus@switch:~$ sudo systemctl reload switchd.service
To disable Tx squelch control, set the interface.<interface-id>.tx_squelch parameter to disabled.
Link Tracking
Link tracking enables you to monitor interfaces automatically and ensure traffic is steered through available redundant paths. This feature prevents traffic blackholing by dynamically managing downlink behavior based on the health of uplinks, ensuring predictable network operations, and improving overall resiliency.
Configure and Enable Link Tracking
To configure and enable link tracking:
- Set link tracking to
enabled. - Create a link tracking group with the set of links (watch interfaces) that you want to monitor.
- You can only configure switch port (swp) interfaces that already exist.
- A group name must be between 1 and 16 characters long. You can use alphanumeric characters, hyphens (-), and underscores (_).
- Set the minimum number of watch interfaces for each group that must be operationally up to keep the associated target interfaces active.
- The minimum number of links must not exceed the number of interfaces configured in the group.
- The default value is 1 when the group has at least one watch interface.
- Associate target interfaces with the link tracking group. These are the interfaces that depend on the health of the watch interfaces in the group.
- The interface must be a switch port (swp).
- You cannot configure an interface as both a watch interface and a target interface.
- Specify the action each group takes when the number of operationally up watch interfaces drops below the minimum threshold. When the number of operationally up watch interfaces meets or exceeds the threshold again, the switch clears the action and restores the target interfaces. You can set the following actions:
protodown-target-interfacemarks the target interfaces as protodown so that the switch does not forward traffic to downstream devices over those links. This is the default action.control-plane-actionnotifies the control plane to reroute traffic away from the affected plane.
When you configure and enable link tracking, the ifplugd service starts. The ifplugd-resync-config-change service restarts and synchronizes the protodown state of the target interfaces based on their link tracking group configuration. When you disable link tracking, the ifplugd service stops.
The following example configures two groups:
- GROUP1 sets the watch interfaces to swp17, swp19, and swp21, and the minimum number of watch interfaces that must be operationally up to 1. The target interfaces are swp7 and swp15, and the action is
control-plane-action. - GROUP2 sets the watch interfaces to swp17, swp24, swp25, and swp31 and the minimum number of watch interfaces that must be operationally up to 2. The target interface is swp8 and the action is
protodown-target-interface.
cumulus@switch:~$ nv set system link-tracking state enabled
cumulus@switch:~$ nv set system link-tracking group GROUP1 watch-interface swp17,19,21
cumulus@switch:~$ nv set system link-tracking group GROUP1 min-links 1
cumulus@switch:~$ nv set interface swp7,15 link-tracking group GROUP1
cumulus@switch:~$ nv set system link-tracking group GROUP1 state-change-action control-plane-action
cumulus@switch:~$ nv set system link-tracking group GROUP2 watch-interface swp17,24-25,31
cumulus@switch:~$ nv set system link-tracking group GROUP2 min-links 2
cumulus@switch:~$ nv set interface swp8 link-tracking group GROUP2
cumulus@switch:~$ nv set system link-tracking group GROUP2 state-change-action protodown-target-interface
cumulus@switch:~$ nv config apply
Edit the following configuration files:
/etc/default/ifplugdsets the watch interfaces to monitor for link state changes./etc/ifplugd/link-tracking.confconfigures link tracking groups and actions.
The example configuration below configures ifplugd to bring down all uplinks when the peer bond goes down in an MLAG environment.
- Edit
/etc/default/ifplugdin a text editor to configure the watch interfaces to monitor for link state changes. The example below configures interface swp17, swp19, swp21, swp24, swp25, and swp31.
# ifplugd Configuration for Link Tracking
#
# Usage:
# Sourced by /etc/init.d/ifplugd and /lib/udev/ifplugd.agent
# to set default values.
#
# Interface Lists:
# - INTERFACES: Interfaces to be monitored by ifplugd
# - HOTPLUG_INTERFACES: Interfaces monitored on hotplug (typically empty)
# Watch interfaces to monitor for link state changes
INTERFACES="swp17 swp19 swp21 swp24 swp25 swp31"
HOTPLUG_INTERFACES=""
# ifplugd Arguments:
# -p: Don't run action script on daemon startup (we run sync once after config
# apply. ifplugd then only runs the script on link state changes)
# -q: Don't run script on daemon shutdown
# -f: Ignore detection failures (continue running if detection fails)
# -u0: Delay after link up = 0 seconds (immediate action)
# -d1: Delay after link down = 1 second (brief delay to avoid flaps)
# -w: Wait until daemon forks (synchronous startup)
# -I: Don't exit on nonzero return values from action script
#
# Note: These values balance responsiveness with flap protection.
# Adjust delays if needed for your environment.
ARGS="-p -q -f -u0 -d1 -w -I"
SUSPEND_ACTION="stop"
- Edit the
/etc/ifplugd/link-tracking.conffile in a text editor to configure link tracking groups. The following example configures GROUP1 and GROUP2.
# Link Tracking Group Configuration
#
# Purpose:
# Map watch interfaces to target interfaces for tracking.
# Read by /etc/ifplugd/ifplugd.action to manage target interfaces when
# watch interfaces fail.
#
# Format:
# GROUP_ID|WATCH_INTERFACES|TARGET_INTERFACES|MIN_LINKS|state-change-action
# GROUP_ID: Unique identifier for the tracking group
# WATCH_INTERFACES: comma-separated interfaces to monitor
# TARGET_INTERFACES: comma-separated interfaces to manage
# MIN_LINKS: minimum watch interfaces that must be up (default 1)
# state-change-action: protodown-target-interface or control-plane-action
#
# Example:
# group-1|swp1,swp2|swp10,swp11|1|protodown-target-interface
#
GROUP1|swp17,swp19,swp21|swp15,swp7|1|control-plane-action
GROUP2|swp17,swp24,swp25,swp31|swp8|2|protodown-target-interface
$ cat /etc/ifplugd/ifplugd-link-tracking.conf
# Auto-generated by NVUE!
# Any local modifications will prevent NVUE from re-generating this file.
# md5sum: 79d87d9a2553351580a38b16e1878267
# ifplugd Link Tracking Maintenance
#
# Sourced by ifplugd-resync-config-change.service on restart (triggered by NVUE).
#
# CLEAR_TARGET_INTERFACES:
# Space-separated list of target interfaces from which to clear the
# link-tracking protodown reason. Other protodown reasons are unchanged.
#
# SYNC_GROUPS:
# When "yes", sync protodown state for all link tracking groups by
# invoking /etc/ifplugd/action.d/99_link_tracking --all-groups after clear.
# When "no", skip group sync.
CLEAR_TARGET_INTERFACES=""
SYNC_GROUPS="yes"
- Restart the
ifplugddaemon to implement the changes:
cumulus@switch:~$ sudo systemctl restart ifplugd.service
Upgrade Notes
If you installed and configured ifplugd manually in Cumulus Linux 5.17 or earlier, Cumulus Linux 5.18 or later preserves the existing ifplugd configuration and behavior after optimized image upgrade. The configuration includes manual configuration in /etc/default/ifplugd and custom action scripts under /etc/ifplugd/action.d/. If the ifplugd service is running before upgrade, the service continues to run and actively manage interfaces. No additional action is required while link tracking remains disabled. Link tracking in Cumulus Linux 5.18 or later is disabled by default.
After you enable and apply link tracking in Cumulus Linux 5.18 or later, feature-managed configuration takes precedence and might overwrite existing manual configuration.
To retain custom interface lists or action logic not supported by link tracking, you can configure traditional snippets.
When you enable link tracking after upgrade, any existing ifplugd instances manually configured and started before enabling link tracking continue to run. Cumulus Linux does not stop or clean up the instances automatically. You must identify and terminate any manually configured ifplugd instances that are no longer required. Failure to do so might result in conflicts with link tracking managed interfaces.
Manage Link Tracking
- To disable link tracking, run the
nv set system link-tracking state disabledcommand. - To remove a target interface from a group, run the
nv unset interface <interface-id> link-tracking groupcommand. - To reset the action back to the default value, run the
nv unset system link-tracking group <group-id> state-change-actioncommand. - To reset the minimum number of watch interfaces to the default value of 1, run the
nv unset system link-tracking group <group-id> min-linkscommand. - To remove a link tracking group, run the
nv unset system link-tracking group <group-id>command. If the group is associated with a target interface, remove the association with thenv unset interface <interface-id> link-tracking groupcommand.
Show Link Tracking Information
To show link tracking configuration, such as the feature state (enabled or disabled) and all configured link tracking groups with their watch interfaces, minimum threshold, and state-change action, run the nv show system link-tracking command.
cumulus@switch:~$ nv show system link-tracking
operational applied
----- ----------- -------
state enabled enabled
group
========
Link Tracking Group Watch Interface Min Links State Change Action
------------------- --------------- --------- --------------------------
GROUP1 swp17 1 control-plane-action
swp19
swp21
GROUP2 swp17 2 protodown-target-interface
swp24
swp25
swp3
To show all the configured link tracking groups, run the nv show system link-tracking group command:
cumulus@switch:~$ nv show system link-tracking group
Link Tracking Group Watch Interface Min Links State Change Action
------------------- --------------- --------- --------------------------
GROUP1 swp17 1 control-plane-action
swp19
swp21
GROUP2 swp17 2 protodown-target-interface
swp24
swp25
swp31
To show details of a specific link tracking group, including its watch interfaces, minimum threshold, and state-change action, run the nv show system link-tracking group <group-id> command:
cumulus@switch:~$ nv show system link-tracking group GROUP2
operational applied
------------------- -------------------------- --------------------------
min-links 2 2
state-change-action protodown-target-interface protodown-target-interface
[watch-interface] swp17 swp17
[watch-interface] swp24 swp24
[watch-interface] swp25 swp25
[watch-interface] swp31 swp31
To show all configured watch interfaces in a specific group, run the nv show system link-tracking group <group-id> watch-interface command:
cumulus@switch:~$ nv show system link-tracking group GROUP2 watch-interface
swp17
swp24
swp25
swp31
To show the link tracking group associated with each interface, run the nv show interface link-tracking command.
cumulus@switch:~$ nv show interface link-tracking
Interface Link Tracking Group Admin Status Oper Status Protodown Protodown Reason
--------- ------------------- ------------ ----------- --------- ----------------
eth0 up up disabled
lo up unknown disabled
mgmt up up disabled
swp1 up down disabled
swp2 up down disabled
swp3 up down disabled
swp4 up down disabled
swp5 up down disabled
swp6 up down disabled
swp7 GROUP1 up down disabled
swp8 GROUP2 up down enabled link-tracking
swp9 up down disabled
swp10 up down disabled
swp11 up down disabled
swp12 up down disabled
swp13 up down disabled
swp14 up down disabled
swp15 GROUP1 up down disabled
swp16 up down disabled
swp17 up up disabled
swp18 up up disabled
swp19 up up disabled
swp20 up up disabled
swp21 up up disabled
swp22 up up disabled
swp23 up down disabled
swp24 up down disabled
swp25 up down disabled
To show the link tracking group associated with a specific interface, run the nv show interface <interface-id> link-tracking command:
cumulus@switch:~$ nv show interface swp8 link-tracking
operational applied
----- ----------- -------
group GROUP2 GROUP2
To show only the interfaces associated with a specific group, run the nv show interface link-tracking --filter "group=<group-name>" command:
cumulus@switch:~$ nv show interface link-tracking --filter "group=GROUP1"
Interface Link Tracking Group Admin Status Oper Status Protodown Protodown Reason
--------- ------------------- ------------ ----------- --------- ----------------
swp7 GROUP1 up down disabled
swp15 GROUP1 up down disabled
Troubleshooting
To verify the protodown state on a target interface, run the sudo ip -d link show <interface-id> command:
cumulus@switch:~$ sudo ip -d link show swp8
10: swp8: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 9216 qdisc pfifo_fast state DOWN mode DEFAULT group default qlen 1000
link/ether 1c:34:da:1b:cc:74 brd ff:ff:ff:ff:ff:ff protodown on protodown_reason <link-tracking> promiscuity 0 allmulti 0 minmtu 68 maxmtu 0
sx_netdev addrgenmode eui64 numtxqueues 1 numrxqueues 1 gso_max_size 65536 gso_max_segs 65535 tso_max_size 65536 tso_max_segs 65535 gro_max_size 65536 switchid ffffffffff01 last_change 1784260523674 carrier_up_count 7 carrier_down_count 8 carrier_changes 15
The following example shows the interface state of a target interface after the action is cleared:
cumulus@switch:~$ sudo ip -d link show swp8
10: swp8: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 9216 qdisc pfifo_fast state UP mode DEFAULT group default qlen 1000
link/ether 1c:34:da:1b:cc:74 brd ff:ff:ff:ff:ff:ff promiscuity 0 allmulti 0 minmtu 68 maxmtu 0
sx_netdev addrgenmode eui64 numtxqueues 1 numrxqueues 1 gso_max_size 65536 gso_max_segs 65535 tso_max_size 65536 tso_max_segs 65535 gro_max_size 65536 switchid ffffffffff01 last_change 1784260564714 carrier_up_count 9 carrier_down_count 9 carrier_changes 18
To view link tracking logs in journalctl, run the sudo journalctl -t ifplugd-link-tracking -f command:
cumulus@switch:~$ sudo journalctl -t ifplugd-link-tracking -f
Jul 17 03:34:21 cumulus ifplugd-link-tracking[859902]: Interface swp24 link state changed, checking link tracking groups
Jul 17 03:34:21 cumulus ifplugd-link-tracking[859907]: Group group-2: Watch interface swp24 is part of this group (min_links=2)
Jul 17 03:34:21 cumulus ifplugd-link-tracking[859917]: Group group-2: 1 watch interface(s) up (min_links=2), applying action to target interfaces: swp8
Jul 17 03:34:21 cumulus ifplugd-link-tracking[859926]: Group group-2: Protodown set ON for target interface swp8 (reason: link-tracking)
Jul 17 03:45:26 cumulus ifplugd-link-tracking[868112]: Interface swp24 link state changed, checking link tracking groups
Jul 17 03:45:26 cumulus ifplugd-link-tracking[868117]: Group group-2: Watch interface swp24 is part of this group (min_links=2)
Jul 17 03:45:26 cumulus ifplugd-link-tracking[868127]: Group group-2: 2 watch interface(s) up (min_links=2), clearing action on target interfaces: swp8
Jul 17 03:45:26 cumulus ifplugd-link-tracking[868131]: Group group-2: Watch interface restored, clearing link-tracking protodown reason for target interface swp8
Jul 17 03:45:26 cumulus ifplugd-link-tracking[868135]: Group group-2: link-tracking reason cleared for swp8
Jul 17 03:45:26 cumulus ifplugd-link-tracking[868140]: Group group-2: Protodown turned off for target interface swp8 (link-tracking cleared, no other reasons)
To view link tracking logs in syslog, run the sudo grep "link-tracking" /var/log/syslog command:
cumulus@switch:~$ sudo grep "link-tracking" /var/log/syslog
2026-07-17T03:20:03.549597+00:00 cumulus ifplugd-link-tracking: Interface swp24 link state changed, checking link tracking groups
2026-07-17T03:20:03.556205+00:00 cumulus ifplugd-link-tracking: Group group-2: Watch interface swp24 is part of this group (min_links=2)
2026-07-17T03:20:03.565774+00:00 cumulus ifplugd-link-tracking: Group group-2: 1 watch interface(s) up (min_links=2), applying action to target interfaces: swp8
2026-07-17T03:20:03.577761+00:00 cumulus ifplugd-link-tracking: Group group-2: Protodown set ON for target interface swp8 (reason: link-tracking)
2026-07-17T03:45:26.527768+00:00 cumulus ifplugd-link-tracking: Interface swp24 link state changed, checking link tracking groups
2026-07-17T03:45:26.534124+00:00 cumulus ifplugd-link-tracking: Group group-2: Watch interface swp24 is part of this group (min_links=2)
2026-07-17T03:45:26.543704+00:00 cumulus ifplugd-link-tracking: Group group-2: 2 watch interface(s) up (min_links=2), clearing action on target interfaces: swp8
2026-07-17T03:45:26.548576+00:00 cumulus ifplugd-link-tracking: Group group-2: Watch interface restored, clearing link-tracking protodown reason for target interface swp8
2026-07-17T03:45:26.555627+00:00 cumulus ifplugd-link-tracking: Group group-2: link-tracking reason cleared for swp8
2026-07-17T03:45:26.563410+00:00 cumulus ifplugd-link-tracking: Group group-2: Protodown turned off for target interface swp8 (link-tracking cleared, no other reasons)
To verify the ifplugd service:
cumulus@switch:~$ sudo systemctl status ifplugd.service
● ifplugd.service - LSB: Brings up/down network automatically
Loaded: loaded (/etc/init.d/ifplugd; generated)
Drop-In: /etc/systemd/system/ifplugd.service.d
└─override.conf
Active: active (running) since Fri 2026-07-17 01:56:33 UTC; 1h 54min ago
Docs: man:systemd-sysv-generator(8)
Tasks: 6 (limit: 18430)
Memory: 1.2M
CPU: 2.032s
CGroup: /system.slice/ifplugd.service
├─788534 /usr/sbin/ifplugd -i swp17 -p -q -f -u0 -d1 -w -I
├─788542 /usr/sbin/ifplugd -i swp19 -p -q -f -u0 -d1 -w -I
├─788550 /usr/sbin/ifplugd -i swp21 -p -q -f -u0 -d1 -w -I
├─788559 /usr/sbin/ifplugd -i swp24 -p -q -f -u0 -d1 -w -I
├─788567 /usr/sbin/ifplugd -i swp25 -p -q -f -u0 -d1 -w -I
└─788575 /usr/sbin/ifplugd -i swp31 -p -q -f -u0 -d1 -w -I
Jul 17 03:20:03 cumulus ifplugd(swp24)[788559]: Program executed successfully.
Jul 17 03:33:57 cumulus ifplugd(swp24)[788559]: Link beat detected.
Jul 17 03:33:57 cumulus ifplugd(swp24)[788559]: Executing '/etc/ifplugd/ifplugd.action swp24 up'.
Jul 17 03:33:57 cumulus ifplugd(swp24)[788559]: Program executed successfully.
Jul 17 03:34:20 cumulus ifplugd(swp24)[788559]: Link beat lost.
Jul 17 03:34:21 cumulus ifplugd(swp24)[788559]: Executing '/etc/ifplugd/ifplugd.action swp24 down'.
Jul 17 03:34:21 cumulus ifplugd(swp24)[788559]: Program executed successfully.
Jul 17 03:45:26 cumulus ifplugd(swp24)[788559]: Link beat detected.
Jul 17 03:45:26 cumulus ifplugd(swp24)[788559]: Executing '/etc/ifplugd/ifplugd.action swp24 up'.
Jul 17 03:45:26 cumulus ifplugd(swp24)[788559]: Program executed successfully.
cumulus@switch:~$ sudo systemctl status ifplugd-resync-config-change.service
○ ifplugd-resync-config-change.service - ifplugd Resync on Config Change
Loaded: loaded (/lib/systemd/system/ifplugd-resync-config-change.service; enabled; preset: enabled)
Active: inactive (dead) since Fri 2026-07-17 03:05:21 UTC; 45min ago
Docs: man:ifplugd(8)
Process: 838723 ExecStart=/etc/ifplugd/ifplugd-resync-config-change.sh (code=exited, status=0/SUCCESS)
Main PID: 838723 (code=exited, status=0/SUCCESS)
CPU: 37ms
Jul 17 03:05:21 cumulus systemd[1]: Starting ifplugd-resync-config-change.service - ifplugd Resync on Config Change...
Jul 17 03:05:21 cumulus systemd[1]: ifplugd-resync-config-change.service: Deactivated successfully.
Jul 17 03:05:21 cumulus systemd[1]: Finished ifplugd-resync-config-change.service - ifplugd Resync on Config Change.
Source Interface File Snippets
Sourcing interface files helps organize and manage the /etc/network/interfaces file. For example:
cumulus@switch:~$ sudo cat /etc/network/interfaces
# The loopback network interface
auto lo
iface lo inet loopback
# The primary network interface
auto eth0
iface eth0 inet dhcp
source /etc/network/interfaces.d/bond0
The contents of the sourced file used above are:
cumulus@switch:~$ sudo cat /etc/network/interfaces.d/bond0
auto bond0
iface bond0
address 14.0.0.9/30
address 2001:ded:beef:2::1/64
bond-slaves swp25 swp26
Mako Templates
ifupdown2 supports Mako-style templates. The Mako template engine processes the interfaces file before parsing.
Use the template to declare cookie-cutter bridges and to declare addresses in the interfaces file:
%for i in [1,12]:
auto swp${i}
iface swp${i}
address 10.20.${i}.3/24
- In Mako syntax, use square brackets (
[1,12]) to specify a list of individual numbers. Userange(1,12)to specify a range of interfaces. - To test your template and confirm it evaluates correctly, run
mako-render /etc/network/interfaces.
To comment out content in Mako templates, use double hash marks (##). For example:
## % for i in range(1, 4):
## auto swp${i}
## iface swp${i}
## % endfor
##
For more Mako template examples, refer to this knowledge base article.
ifupdown Scripts
Unlike the traditional ifupdown system, ifupdown2 does not run scripts installed in /etc/network/*/ automatically to configure network interfaces.
To enable or disable ifupdown2 scripting, edit the addon_scripts_support line in the /etc/network/ifupdown2/ifupdown2.conf file. 1 enables scripting and 2 disables scripting. For example:
cumulus@switch:~$ sudo nano /etc/network/ifupdown2/ifupdown2.conf
# Support executing of ifupdown style scripts.
# Note that by default python addon modules override scripts with the same name
addon_scripts_support=1
ifupdown2 sets the following environment variables when executing commands:
$IFACErepresents the physical name of the interface; for example,br0or vxlan42. The name comes from the/etc/network/interfacesfile.$LOGICALrepresents the logical name (configuration name) of the interface.$METHODrepresents the address method; for example, loopback, DHCP, DHCP6, manual, static, and so on.$ADDRFAMrepresents the address families associated with the interface in a comma-separated list; for example,"inet,inet6".
Show Interface Information
To show the administrative and physical (operational) state of all interfaces on the switch:
cumulus@switch:~$ nv show interface
Interface Admin Status Oper Status Speed MTU Type Remote Host Remote Port Summary
--------- ------------ ----------- ----- ----- -------- --------------- ----------- ----------------------------------------
eth0 up up 1G 1500 eth oob-mgmt-switch swp10 IP Address: 192.168.200.11/24
IP Address: fe80::4638:39ff:fe22:17a/64
lo up unknown 65536 loopback IP Address: 127.0.0.1/8
IP Address: ::1/128
mgmt up up 65575 vrf IP Address: 127.0.0.1/8
IP Address: ::1/128
swp1 up up 1G 9216 swp IP Address: fe80::4ab0:2dff:fe50:fecf/64
swp2 down down 1500 swp
swp3 down down 1500 swp
swp4 down down 1500 swp
swp5 down down 1500 swp
swp6 down down 1500 swp
swp7 down down 1500 swp
...
To show the administrative and physical (operational) state of an interface, and the date and time the physical state of the interface changed:
cumulus@switch:~$ nv show interface swp1
operational applied
----------------------- ----------------- -------
...
oper-status up
admin-status up
oper-status-last-change 2024/10/11 19:12:16.339
Run the ip link show dev <interface-id> command.
In the following example, swp1 is administratively UP and the physical link is UP (LOWER_UP).
cumulus@switch:~$ ip link show dev swp1
3: swp1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP mode DEFAULT qlen 500
link/ether 44:38:39:00:03:c1 brd ff:ff:ff:ff:ff:ff
To show the last time (date and time) the operational state of an interface changed and the number of carrier transitions for each interface (from the time of interface creation):
cumulus@switch:~$ nv show interface --view=carrier-stats
Interface Oper Status Up Count Down Count Total State Changes Last State Change
-------------- ----------- -------- ---------- ------------------- -----------------------
BLUE up 0 0 0 Never
RED up 0 0 0 Never
bond1 up 2 1 3 2024/10/11 19:14:59.265
bond2 up 1 0 1 2024/10/11 19:12:18.817
bond3 up 1 0 1 2024/10/11 19:12:18.833
br_default up 2 2 4 2024/10/11 19:12:15.216
eth0 up 1 1 2 2024/10/11 19:12:02.157
lo unknown 0 0 0 Never
mgmt up 0 0 0 Never
peerlink up 1 0 1 2024/10/11 19:12:06.913
peerlink.4094 up 1 0 1 2024/10/11 19:12:06.915
swp1 up 2 2 4 2024/10/11 19:12:16.339
swp2 up 2 2 4 2024/10/11 19:12:16.345
swp3 up 2 2 4 2024/10/11 19:12:16.351
swp4 down 1 1 2 2024/10/11 19:11:28.936
swp5 down 1 1 2 2024/10/11 19:11:28.936
swp6 down 1 1 2 2024/10/11 19:11:28.936
swp7 down 1 1 2 2024/10/11 19:11:28.936
...
In the example above:
Last State Changeshows the timestamp of the last operational state change.Total State Changesshows the total number of transitions in the carrier state.Up Countshows the number of times the carrier transitioned to an UP state.Down Countshows the number of times the carrier transitioned to a DOWN state.
To show the date and time the operational state of a specific interface changes (oper-status-last-change) and the number of carrier transitions (carrier-transitions, carrier-up-count, carrier-down-count):
cumulus@switch:~$ nv show interface swp1 link
operational applied pending
----------------------- ----------------------- ------- -------
admin-status up
oper-status up
oper-status-last-change 2024/10/11 19:12:16.339
protodown disabled
auto-negotiate disabled enabled
duplex full full full
speed 1G auto auto
mac-address 48:b0:2d:fa:a1:14
fec auto auto
mtu 9000 9216 9216
fast-linkup disabled
[breakout]
state up up up
flap-protection
enable on on
stats
in-bytes 1.96 MB
in-pkts 16399
in-drops 0
in-errors 0
out-bytes 2.37 MB
out-pkts 24669
out-drops 0
out-errors 0
carrier-transitions 4
carrier-up-count 2
carrier-down-count 2
To show the number of carrier transitions only (carrier-transitions, carrier-up-count, carrier-down-count) for a specific interface, run the nv show interface <interface-id> link stats command.
To show the assigned IP address on an interface:
cumulus@switch:~$ nv show interface lo ipv4 address
-------------
10.0.1.12/32
10.10.10.1/32
127.0.0.1/8
::1/128
cumulus@switch:~$ ip addr show swp1
3: swp1: <BROADCAST,MULTICAST,SLAVE,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 500
link/ether 44:38:39:00:03:c1 brd ff:ff:ff:ff:ff:ff
inet 192.0.2.1/30 scope global swp1
inet 192.0.2.2/30 scope global swp1
inet6 2001:DB8::1/126 scope global tentative
valid_lft forever preferred_lft forever
To show the description (alias) for an interface:
cumulus@switch$ nv show interface swp1
operational applied
------------------------ ---------------------------- -----------------
...
description hypervisor_port_1 hypervisor_port_1
ip
vrrp
state disabled
igmp
state disabled
neighbor-discovery
state enabled
router-advertisement
state disabled
home-agent
state disabled
[rdnss]
[dnssl]
[prefix]
ipv4
forward enabled
ipv6
state enabled
forward enabled
vrf default
[address] fe80::4ab0:2dff:feeb:db72/64
[gateway]
...
cumulus@switch$ ip link show swp1
3: swp1: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast state DOWN mode DEFAULT qlen 500
link/ether aa:aa:aa:aa:aa:bc brd ff:ff:ff:ff:ff:ff
alias hypervisor_port_1
You can monitor the traffic rate and PPS for an interface to ensure optimal network performance and reliability; refer to Commands to monitor interface traffic rate and PPS.
Interface Fault Detection
You can view interface status along with any detected local or remote fault with the nv show interface status command:
cumulus@switch:mgmt:~$ nv show interface status
Interface Admin Status Oper Status Protodown Protodown Reason Fault
--------- ------------ ----------- --------- ---------------- --------
...
swp45 up down disabled Local Fault
swp46 up down disabled Remote Fault
swp47 down down disabled No Fault
swp48 down down disabled No Fault
...
To view additional fault information for a specific interface, run the nv show interface <interface> link phy detail command:
cumulus@switch:mgmt:~$ nv show interface swp45 link phy detail
operational
-------------------------------- -------------------
...
linkdown-reason-code-local 23
linkdown-reason-status-local CABLE_WAS_UNPLUGGED
linkdown-reason-code-remote 1
linkdown-reason-status-remote UNKNOWN_REASON
...
- Interface fault detection is supported on Spectrum-4 and later.
- Fault status reported by the
nv show interface statuscommand is only supported on physical switch ports and breakout interfaces. Fault state is not applicable to logical interfaces such as VLAN sub-interfaces, SVIs, loopback interfaces, VRF interfaces, and bonds. - Fault detection data is not retained across reboots or when the
switchdservice is restarted.
Considerations
Even though ifupdown2 supports the inclusion of multiple iface stanzas for the same interface, use a single iface stanza for each interface. If you must specify more than one iface stanza; for example, if the configuration for a single interface comes from many places, like a template or a sourced file, make sure the stanzas do not specify the same interface attributes. Otherwise, you see unexpected behavior.
In the following example, swp1 is in two files: /etc/network/interfaces and /etc/network/interfaces.d/speed_settings. ifupdown2 parses this configuration because the same attributes are not in multiple iface stanzas.
cumulus@switch:~$ sudo cat /etc/network/interfaces
source /etc/network/interfaces.d/speed_settings
auto swp1
iface swp1
address 10.0.14.2/24
cumulus@switch:~$ cat /etc/network/interfaces.d/speed_settings
auto swp1
iface swp1
link-speed 1000
link-duplex full
ifupdown2 and sysctl
For sysctl commands in the pre-up, up, post-up, pre-down, down, and post-down lines that use the
$IFACE variable, if the interface name contains a dot (.), ifupdown2 does not change the name to work with sysctl. For example, the interface name bridge.1 does not convert to bridge/1.
ifupdown2 and the gateway Parameter
The default route that the gateway parameter creates in ifupdown2 does not install in FRR, therefore does not redistribute into other routing protocols. Define a static default route instead, which installs in FRR and redistributes, if needed.
The following shows an example of the /etc/network/interfaces file when you use a static route instead of a gateway parameter:
auto swp2
iface swp2
address 172.16.3.3/24
up ip route add default via 172.16.3.2
Interface Name Limitations
Interface names can be a maximum of 15 characters. You cannot use a number for the first character and you cannot include a dash (-) in the name. In addition, you cannot use any name that matches with the regular expression .{0,13}\-v.*.
If you encounter issues, remove the interface name from the /etc/network/interfaces file, then restart the networking.service.
cumulus@switch:~$ sudo nano /etc/network/interfaces
cumulus@switch:~$ sudo systemctl restart networking.service
IP Address Scope
ifupdown2 does not honor the configured IP address scope setting in the /etc/network/interfaces file and treats all addresses as global. It does not report an error. Consider this example configuration:
auto swp2
iface swp2
address 35.21.30.5/30
address 3101:21:20::31/80
scope link
When you run ifreload -a on this configuration, ifupdown2 considers all IP addresses as global.
cumulus@switch:~$ ip addr show swp2
5: swp2: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
link/ether 74:e6:e2:f5:62:82 brd ff:ff:ff:ff:ff:ff
inet 35.21.30.5/30 scope global swp2
valid_lft forever preferred_lft forever
inet6 3101:21:20::31/80 scope global
valid_lft forever preferred_lft forever
inet6 fe80::76e6:e2ff:fef5:6282/64 scope link
valid_lft forever preferred_lft forever
To work around this issue, configure the IP address scope:
In the /etc/network/interfaces file, configure the IP address scope using post-up ip address add <address> dev <interface-id> scope <scope>. For example:
auto swp6
iface swp6
post-up ip address add 71.21.21.20/32 dev swp6 scope site
Then run the ifreload -a command on this configuration.
The following configuration shows the correct scope:
cumulus@switch:~$ ip addr show swp6
9: swp6: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
link/ether 74:e6:e2:f5:62:86 brd ff:ff:ff:ff:ff:ff
inet 71.21.21.20/32 scope site swp6
valid_lft forever preferred_lft forever
inet6 fe80::76e6:e2ff:fef5:6286/64 scope link
valid_lft forever preferred_lft forever