Configuring switchd

switchd is the daemon at the heart of Cumulus Linux. It communicates between the switch and Cumulus Linux, and all the applications running on Cumulus Linux.

The switchd configuration is stored in /etc/cumulus/switchd.conf.

The switchd File System

switchd also exports a file system, mounted on /cumulus/switchd, that presents all the switchd configuration options as a series of files arranged in a tree structure. You can see the contents by parsing the switchd tree; run tree /cumulus/switchd. The output below is for a switch with one switch port configured:

cumulus@switch:~$ sudo tree /cumulus/switchd/
/cumulus/switchd/
|-- config
|   |-- acl
|   |   |-- non_atomic_update_mode
|   |   `-- optimize_hw
|   |-- arp
|   |   `-- next_hops
|   |-- buf_util
|   |   |-- measure_interval
|   |   `-- poll_interval
|   |-- coalesce
|   |   |-- reducer
|   |   `-- timeout
|   |-- disable_internal_restart
|   |-- ignore_non_swps
|   |-- interface
|   |   |-- swp1
|   |   |   `-- storm_control
|   |   |       |-- broadcast
|   |   |       |-- multicast
|   |   |       `-- unknown_unicast
|   |-- logging
|   |-- route
|   |   |-- host_max_percent
|   |   `-- table
|   `-- stats
|       `-- poll_interval
|-- ctrl
|   |-- acl
|   |-- hal
|   |   `-- resync
|   |-- logger
|   |-- netlink
|   |   `-- resync
|   |-- resync
|   `-- sample
|       `-- ulog_channel
|-- run
|   `-- route_info
|       |-- ecmp_nh
|       |   |-- count
|       |   |-- max
|       |   `-- max_per_route
|       |-- host
|       |   |-- count
|       |   |-- count_v4
|       |   |-- count_v6
|       |   `-- max
|       |-- mac
|       |   |-- count
|       |   `-- max
|       `-- route
|           |-- count_0
|           |-- count_1
|           |-- count_total
|           |-- count_v4
|           |-- count_v6
|           |-- mask_limit
|           |-- max_0
|           |-- max_1
|           `-- max_total
`-- version

Configure switchd Parameters

You can use cl-cfg to configure many switchd parameters at runtime (like ACLs, interfaces, and route table utilization), which minimizes disruption to your running switch. However, some options are read only and cannot be configured at runtime.

For example, to see data related to routes, run:

cumulus@switch:~$ sudo cl-cfg -a switchd | grep route
route.table = 254
route.host_max_percent = 50
cumulus@cumulus:~$

To modify the configuration, run cl-cfg -w. For example, to set the buffer utilization measurement interval to 1 minute, run:

cumulus@switch:~$ sudo cl-cfg -w switchd buf_util.measure_interval=1

To verify that the value changed, use grep:

cumulus@switch:~$ cl-cfg -a switchd | grep buf
buf_util.poll_interval = 0
buf_util.measure_interval = 1

Restart switchd

Whenever you modify any switchd hardware configuration file (typically changing any *.conf file that requires making a change to the switching hardware, like /etc/cumulus/datapath/traffic.conf), you must restart switchd for the change to take effect:

cumulus@switch:~$ sudo systemctl restart switchd.service