Power over Ethernet - PoE
Cumulus Linux supports Power over Ethernet (PoE) and PoE+, so certain Cumulus Linux switches can supply power from Ethernet switch ports to enabled devices over the Ethernet cables that connect them. PoE is capable of powering devices up to 15W, while PoE+ can power devices up to 30W. Configuration for power negotiation is done over LLDP.
The currently supported platforms include:
- Cumulus Express CX-1048-P
- EdgeCore AS4610-54P
PoE Basics
PoE functionality is provided by the cumulus-poe package. When a powered device is connected to the switch via an Ethernet cable:
- If the available power is greater than the power required by the connected device, power is supplied to the switch port, and the device powers on
- If available power is less than the power required by the connected device and the switch port’s priority is less than the port priority set on all powered ports, power is not supplied to the port
- If available power is less than the power required by the connected device and the switch port’s priority is greater than the priority of a currently powered port, power is removed from lower priority port(s) and power is supplied to the port
- If the total consumed power exceeds the configured power limit of the power source, low priority ports are turned off. In the case of a tie, the port with the lower port number gets priority
Power is available as follows:
| PSU 1 | PSU 2 | PoE Power Budget |
|---|---|---|
| 920W | x | 750W |
| x | 920W | 750W |
| 920W | 920W | 1650W |
The AS4610-54P has an LED on the front panel to indicate PoE status:
- Green: The
poeddaemon is running and no errors are detected - Yellow: One or more errors are detected or the
poeddaemon is not running
Link state and PoE state are completely independent of each other. When a link is brought down on a particular port using ip link <port> down, power on that port is not turned off; however, LLDP negotiation is not possible.
Configure PoE
You use the poectl command utility to configure PoE on a switch that supports the feature. You can:
- Enable or disable PoE for a given switch port
- Set a switch port’s PoE priority to one of three values: low, high or critical
The PoE configuration resides in /etc/cumulus/poe.conf. The file lists all the switch ports, whether PoE is enabled for those ports and the priority for each port.
By default, PoE and PoE+ are enabled on all Ethernet/1G switch ports, and these ports are set with a low priority. Switch ports can have low, high or critical priority.
There is no additional configuration for PoE+.
To change the priority for one or more switch ports, run poectl -p swp# [low|high|critical]. For example:
cumulus@switch:~$ sudo poectl -p swp1-swp5,swp7 high
To disable PoE for one or more ports, run poectl -d [port_numbers]:
cumulus@switch:~$ sudo poectl -d swp1-swp5,swp7
To display PoE information for a set of switch ports, run poectl -i [port_numbers]:
cumulus@switch:~$ sudo poectl -i swp10-swp13
Port Status Allocated Priority PD type PD class Voltage Current Power
----- -------------------- ----------- -------- ----------- -------- ------- ------- ---------
swp10 connected negotiating low IEEE802.3at 4 53.5 V 25 mA 3.9 W
swp11 searching n/a low IEEE802.3at none 0.0 V 0 mA 0.0 W
swp12 connected n/a low IEEE802.3at 2 53.5 V 25 mA 1.4 W
swp13 connected 51.0 W low IEEE802.3at 4 53.6 V 72 mA 3.8 W
The Status can be one of the following:
- searching: PoE is enabled but no device has been detected.
- disabled: The PoE port has been configured as disabled.
- connected: A powered device is connected and receiving power.
- power-denied: There is insufficient PoE power available to enable the connected device.
The Allocated column displays how much PoE power has been allocated to the port, which can be one of the following:
- n/a: No device is connected or the connected device does not support LLDP negotiation.
- negotiating: An LLDP-capable device is connected and is negotiating for PoE power.
- XX.X W: An LLDP-capable device has negotiated for XX.X watts of power (for example, 51.0 watts for swp13 above).
To see all the PoE information for a switch, run poectl -s:
cumulus@switch:~$ poectl -s
System power:
Total: 730.0 W
Used: 11.0 W
Available: 719.0 W
Connected ports:
swp11, swp24, swp27, swp48
The set commands (priority, enable, disable) either succeed silently or display an error message if the command fails.
The poectl command takes the following arguments:
| Argument |
Description |
|---|---|
-h, --help |
Show this help message and exit |
-i, --port-info<port-list> |
Returns detailed information for the specified ports. You can specify a range of ports. For example: -i swp1-swp5,swp10.Note: On an Edge-Core AS4610-54P switch, the voltage reported by the poectl -i command and measured through a power meter connected to the device varies by 5V. The current and power readings are correct and no difference is seen for them. |
-a, --all |
Returns PoE status and detailed information for all ports. |
-p, --priority<port-list> <priority> |
Sets priority for the specified ports: low, high, critical. |
-d, --disable-ports <port-list> |
Disables PoE operation on the specified ports. |
-e, --enable-ports <port-list> |
Enables PoE operation on the specified ports. |
-s, --system |
Returns PoE status for the entire switch. |
-r, --reset <port-list> |
Performs a hardware reset on the specified ports. Use this if one or more ports are stuck in an error state. This does not reset any configuration settings for the specified ports. |
-v, --version |
Displays version information. |
-j, --json |
Displays output in JSON format. |
--save |
Saves the current configuration. The saved configuration is automatically loaded on system boot. |
--load |
Loads and applies the saved configuration. |
Troubleshooting
You can troubleshoot PoE and PoE+ using the following utilities and files:
poectl -s, as described above.- The Cumulus Linux
cl-supportscript, which includes PoE-related output frompoed.conf,syslog,poectl --diag-infoandlldpctl. lldpcli show neighbors ports <swp> protocol lldp hidden detailstcpdump -v -v -i <swp> ether proto 0x88cc- The contents of the PoE/PoE+
/etc/lldpd.d/poed.confconfiguration file, as described above.
Verify the Link Is Up
LLDP requires network connectivity, so verify that the link is up.
cumulus@switch:~$ net show interface swp20
Name MAC Speed MTU Mode
-- ------ ----------------- ------- ----- ---------
UP swp20 44:38:39:00:00:04 1G 1500 Access/L2
View LLDP Information Using lldpcli
You can run lldpcli to view the LLDP information that has been received on a switch port. For example:
cumulus@switch:~$ sudo lldpcli show neighbors ports swp20 protocol lldp hidden details
-------------------------------------------------------------------------------
LLDP neighbors:
-------------------------------------------------------------------------------
Interface: swp20, via: LLDP, RID: 2, Time: 0 day, 00:03:34
Chassis:
ChassisID: mac 68:c9:0b:25:54:7c
SysName: ihm-ubuntu
SysDescr: Ubuntu 14.04.2 LTS Linux 3.14.4+ #1 SMP Thu Jun 26 00:54:44 UTC 2014 armv7l
MgmtIP: fe80::6ac9:bff:fe25:547c
Capability: Bridge, off
Capability: Router, off
Capability: Wlan, off
Capability: Station, on
Port:
PortID: mac 68:c9:0b:25:54:7c
PortDescr: eth0
PMD autoneg: supported: yes, enabled: yes
Adv: 10Base-T, HD: yes, FD: yes
Adv: 100Base-TX, HD: yes, FD: yes
MAU oper type: 100BaseTXFD - 2 pair category 5 UTP, full duplex mode
MDI Power: supported: yes, enabled: yes, pair control: no
Device type: PD
Power pairs: spare
Class: class 4
Power type: 2
Power Source: Primary power source
Power Priority: low
PD requested power Value: 51000
PSE allocated power Value: 51000
UnknownTLVs:
TLV: OUI: 00,01,42, SubType: 1, Len: 1 05
TLV: OUI: 00,01,42, SubType: 1, Len: 1 0D
-------------------------------------------------------------------------------
View LLDP Information Using tcpdump
You can use tcpdump to view the LLDP frames being transmitted and received. For example:
cumulus@switch:~$ sudo tcpdump -v -v -i swp20 ether proto 0x88cc
tcpdump: listening on swp20, link-type EN10MB (Ethernet), capture size 262144 bytes
18:41:47.559022 LLDP, length 211
Chassis ID TLV (1), length 7
Subtype MAC address (4): 00:30:ab:f2:d7:a5 (oui Unknown)
0x0000: 0400 30ab f2d7 a5
Port ID TLV (2), length 6
Subtype Interface Name (5): swp20
0x0000: 0573 7770 3230
Time to Live TLV (3), length 2: TTL 120s
0x0000: 0078
System Name TLV (5), length 13: dni-3048up-09
0x0000: 646e 692d 3330 3438 7570 2d30 39
System Description TLV (6), length 68
Cumulus Linux version 3.0.1~1466303042.2265c10 running on dni 3048up
0x0000: 4375 6d75 6c75 7320 4c69 6e75 7820 7665
0x0010: 7273 696f 6e20 332e 302e 317e 3134 3636
0x0020: 3330 3330 3432 2e32 3236 3563 3130 2072
0x0030: 756e 6e69 6e67 206f 6e20 646e 6920 3330
0x0040: 3438 7570
System Capabilities TLV (7), length 4
System Capabilities [Bridge, Router] (0x0014)
Enabled Capabilities [Router] (0x0010)
0x0000: 0014 0010
Management Address TLV (8), length 12
Management Address length 5, AFI IPv4 (1): 10.0.3.190
Interface Index Interface Numbering (2): 2
0x0000: 0501 0a00 03be 0200 0000 0200
Management Address TLV (8), length 24
Management Address length 17, AFI IPv6 (2): fe80::230:abff:fef2:d7a5
Interface Index Interface Numbering (2): 2
0x0000: 1102 fe80 0000 0000 0000 0230 abff fef2
0x0010: d7a5 0200 0000 0200
Port Description TLV (4), length 5: swp20
0x0000: 7377 7032 30
Organization specific TLV (127), length 9: OUI IEEE 802.3 Private (0x00120f)
Link aggregation Subtype (3)
aggregation status [supported], aggregation port ID 0
0x0000: 0012 0f03 0100 0000 00
Organization specific TLV (127), length 9: OUI IEEE 802.3 Private (0x00120f)
MAC/PHY configuration/status Subtype (1)
autonegotiation [supported, enabled] (0x03)
PMD autoneg capability [10BASE-T fdx, 100BASE-TX fdx, 1000BASE-T fdx] (0x2401)
MAU type 100BASEFX fdx (0x0012)
0x0000: 0012 0f01 0324 0100 12
Organization specific TLV (127), length 12: OUI IEEE 802.3 Private (0x00120f)
Power via MDI Subtype (2)
MDI power support [PSE, supported, enabled], power pair spare, power class class4
0x0000: 0012 0f02 0702 0513 01fe 01fe
Organization specific TLV (127), length 5: OUI Unknown (0x000142)
0x0000: 0001 4201 0d
Organization specific TLV (127), length 5: OUI Unknown (0x000142)
0x0000: 0001 4201 01
End TLV (0), length 0
Log poed Events in syslog
The poed service logs the following events to syslog when:
- A switch provides power to a powered device.
- A device that was receiving power is removed.
- The power available to the switch changes.
- Errors are detected.