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Switch Port Configuration

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Esti Lederer edited this page Aug 25, 2021 · 49 revisions

In most cases, the configuration of a port’s parameters can be done using ip, ifconfig, ifup2, ifdown2, ifquery or ethtool linux commands. The detailed command description and usage examples are provided in the following sections.

The following ethtool commands are not supported:

  • –m command to read SFP module information.
  • –p command to test LEDs on a port.

Port Configuration

Port Identification

In order to specify the corresponding switch port name in Linux, use the following udev rule. It sets the interface name in the kernel driver, based on kernel port properties, such as switch ID and port ID.
SUBSYSTEM=="net", ACTION=="add", ATTR{phys_switch_id}=="00", ATTR{phys_port_name}!="", NAME="sw0p$attr{phys_port_name}"

Port State

Use one of the following commands to set the port administrative status:

ip link set sw1p1 [up | down]
ifconfig sw1p1 [up | down]
ifup2 sw1p1
ifdown2 sw1p1

Port Maximum Transmission Unit (MTU)

The port Maximum Transmission Unit (MTU) can be set using the following command:
ip link set dev sw1p1 mtu 1500

NOTES:

  • The driver supports up to three different MTU settings.
  • Only odd numbers are supported for Maximum Receive Unit (MRU) configuration on the port. This is in keeping with the requirement that MTU is changed together with MRU.

Port MAC Address

The port MAC address can be set using the following command:
ip link set dev sw1p1 address 00:00:00:00:00:02

NOTE: Only the least significant byte of MAC address can be configured on the port. The rest of the MAC address is a common base for all ports.

Port Speed

The port speed can be set using the following command (the speed value is in Mb/s.):
ethtool -s sw1p1 speed 1000

NOTES:

  • Before setting the speed, make sure to configure the port media type.
  • The speed can only be set if auto-negotiation is disabled. If you pass a speed parameter when auto-neogtiation is enabled, it is ignored.

Port Duplex Mode

The port duplex mode can be set using the following command: ethtool -s sw1p1 duplex [half|full]

NOTE: duplex can only be set if auto-neogtiation is disabled. If you pass duplex parameter when auto-neogtiation is enabled, it is ignored.

Port Information

To view the port status and configuration, use the ifconfig, ip link show and ethtool commands.

ip link show sw1pX

The ifconfig and ip link show commands provide information about administrative and operational status, MTU and MAC address. ifconfig also provides some basic port counters.

amzgo-host# ip link show sw1p1
7: sw1p1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP mode DEFAULT group default qlen 1000
    link/ether 00:00:00:00:00:01 brd ff:ff:ff:ff:ff:ff

ethtool sw1pX

The ethtool command provides information about current speed and duplex, auto-negotiation status, supported and advertised link modes, connector type and statistics.

The following are examples of output.

Output Example: Low Speed Port

amzgo-host# ethtool sw1p1
Settings for sw1p1:
# Supported media type, link modes and FEC taken from PHY/MPD
        Supported ports: [ TP ] 
        Supported link modes:   10baseT/Half 10baseT/Full 
                                100baseT/Half 100baseT/Full 
                                1000baseT/Full 
        Supported pause frame use: No
        Supports auto-negotiation: Yes
        Supported FEC modes: None
# Advertised link modes and FEC, section should display actual modes if the port is administratively UP and autoneg is ON, ‘not reported’ otherwise
        Advertised link modes:  10baseT/Half 10baseT/Full 
                                100baseT/Half 100baseT/Full 
                                1000baseT/Full 
        Advertised pause frame use: No
# section always displays “Yes” as PHY is advertising at least one mode
        Advertised auto-negotiation: Yes
        Advertised FEC modes: None
# link partner capability, section should be displayed with actual capability if the link is established, hidden otherwise
        Link partner advertised link modes:  10baseT/Half 10baseT/Full 
                                             100baseT/Half 100baseT/Full 
                                             1000baseT/Full 
        Link partner advertised pause frame use: No
        Link partner advertised auto-negotiation: Yes
        Link partner advertised FEC modes: Not reported
# section should display actual speed and duplex if the link is established, “Unknown” otherwise
        Speed: 1000Mb/s
        Duplex: Full
# section should display the actual port media type
        Port: Twisted Pair
# PHYAD and Transceiver sections are not supported, default values from Linux are displayed
        PHYAD: 0
        Transceiver: internal
# section should display the actual status of auto negotiation 
        Auto-negotiation: on
# section should display the actual MDI/MDI-X mode
        MDI-X: off
# section should display the actual port operational status
        Link detected: yes

Output Example: High Speed Port

# Supported media type
        Supported ports: [ TP FIBRE ]  
# Section is dynamically changing and displays the supported link modes for current port media type
        Supported link modes:   1000baseT/Full 
                                1000baseKX/Full 
                                10000baseKR/Full 
        Supported pause frame use: No
# Supported auto negotiation should be “Yes” only for TP port, “No” for Fiber 
        Supports auto-negotiation: Yes
# Section is dynamically changing and displays the supported FEC modes for current port media type
        Supported FEC modes: None BaseR
# Section should display actual advertising link modes for TP port type, “Not reported” for Fiber
        Advertised link modes:  Not reported
        Advertised pause frame use: No
        Advertised auto-negotiation: No
        Advertised FEC modes: Not reported
# link partner capability section should not be displayed for SFP ports
# Section should display actual speed and duplex if the link is established, “Unknown” otherwise
        Speed: 10000Mb/s
        Duplex: Full
# section should display the actual port media type
        Port: Twisted Pair
# PHYAD and Transceiver sections are not supported, default values from Linux are displayed
        PHYAD: 0
        Transceiver: internal
# section should display the actual status of auto negotiation for TP port type, always “off” for Fiber
        Auto-negotiation: off
# section is always displayed as Unknown, not supported for SFP ports
        MDI-X: Unknown
# section should display the actual port operational status
     Link detected: yes

Port Auto Negotiation

Port auto-negotiation can be enabled/disabled using following command:
ethtool -s sw1p1 autoneg [on | off]

NOTE: The ethtool -r command to restart the auto negotiation is supported only for 1G low speed copper ports.

Linux defines following interface modes for advertising to the remote side:

Mask Mode
0x001 10baseT Half
0x001 10baseT Half
0x002 10baseT Full
0x004 100baseT Half
0x008 100baseT Full
0x80000000000000000 100baseT1 Full
0x010 1000baseT Half
0x020 1000baseT Full
0x100000000000000000 1000baseT1 Full
0x20000 1000baseKX Full
0x20000000000 1000baseX Full
0x800000000000 2500baseT Full
0x8000 2500baseX Full
0x1000000000000 5000baseT Full
0x1000 10000baseT Full
0x40000 10000baseKX4 Full
0x80000 10000baseKR Full
0x100000 10000baseR_FEC
0x40000000000 10000baseCR Full
0x80000000000 10000baseSR Full
0x100000000000 10000baseLR Full
0x200000000000 10000baseLRM Full
0x400000000000 10000baseER Full
0x200000 20000baseMLD2 Full
0x400000 20000baseKR2 Full
0x80000000 25000baseCR Full
0x100000000 25000baseKR Full
0x200000000 25000baseSR Full
0x800000 40000baseKR4 Full
0x1000000 40000baseCR4 Full
0x2000000 40000baseSR4 Full
0x4000000 40000baseLR4 Full
0x400000000 50000baseCR2 Full
0x800000000 50000baseKR2 Full
0x10000000000 50000baseSR2 Full
0x10000000000000 50000baseKR Full
0x20000000000000 50000baseSR Full
0x40000000000000 50000baseCR Full
0x80000000000000 50000baseLR_ER_FR Full
0x100000000000000 50000baseDR Full
0x8000000 56000baseKR4 Full
0x10000000 56000baseCR4 Full
0x20000000 56000baseSR4 Full
0x40000000 56000baseLR4 Full
0x1000000000 100000baseKR4 Full
0x2000000000 100000baseSR4 Full
0x4000000000 100000baseCR4 Full
0x8000000000 100000baseLR4_ER4 Full
0x200000000000000 100000baseKR2 Full
0x400000000000000 100000baseSR2 Full
0x800000000000000 100000baseCR2 Full
0x1000000000000000 100000baseLR2_ER2_FR2 Full
0x2000000000000000 100000baseDR2 Full
0x4000000000000000 200000baseKR4 Full
0x8000000000000000 200000baseSR4 Full
0x10000000000000000 200000baseLR4_ER4_FR4 Full
0x20000000000000000 200000baseDR4 Full
0x40000000000000000 200000baseCR4 Full

In order to advertise some modes, you need to prepare the mask using “OR” operation for target modes and pass it to the ethtool command.
For example:
ethtool -s sw1p1 advertise 0x80000

If auto negotiation is enabled, the Prestera driver should verify inbound advertising modes and print an error message whether some unsupported mode has occurred. If auto-negotiation is disabled, the driver ignores the advertising mode setting.

The configuration of auto-negotiation mechanism is different for low and high speed ports:

  • For low-speed ports, the auto-negotiation parameters should be taken (or applied) from (to) PHY directly. The user has a full control of auto-negotiation configuration on the port.
  • For high-speed SFP ports, only 802.3ap auto-negotiation is supported. The user can enable/disable 802.3ap auto-negotiation on a port and configure the advertised modes. The 802.3ap mode is supported only for TP port type.

NOTE: Auto-negotiation on Copper SFP with RJ-45 module using a Prestera driver is not supported.

Port Statistics

These are the types of port statistics:

  • Software Statistics account for packets trapped to the CPU or packets sent from the CPU.
  • Hardware Statistics account for all packets going through the port, including those not trapped to or originating from the CPU.

Software Statistics

The ifstat tool can be used to query the port's software statistics.

Hardware Statistics

Use one of the following commands to review port hardware statistics:

ip –s link show sw1pX
Ifconfig sw1pX
ethtool –S sw1pX

The ip –s link show and ifconfig commands display basic hardware statistics in rtnl_link_stats64 linux format.

7: sw1p1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP mode DEFAULT group default qlen 1000
    link/ether 00:00:00:00:00:01 brd ff:ff:ff:ff:ff:ff
    RX: bytes  packets  errors  dropped overrun mcast   
    3150       41       0       0       0       41      
    TX: bytes  packets  errors  dropped carrier collsns 
    3056       40       0       0       0       0

The ethtool command displays detailed port hardware counters.

amzgo-host# ethtool -S sw1p1
NIC statistics:
     good_octets_received: 3150
     bad_octets_received: 0
     mac_trans_error: 0
     broadcast_frames_received: 0
     multicast_frames_received: 41
     frames_64_octets: 0
     frames_65_to_127_octets: 81
     frames_128_to_255_octets: 0
     frames_256_to_511_octets: 0
     frames_512_to_1023_octets: 0
     frames_1024_to_max_octets: 0
     excessive_collision: 0
     multicast_frames_sent: 40
     broadcast_frames_sent: 0
     fc_sent: 0
     fc_received: 0
     buffer_overrun: 0
     undersize: 0
     fragments: 0
     oversize: 0
     jabber: 0
     rx_error_frame_received: 0
     bad_crc: 0
     collisions: 0
     late_collision: 0
     unicast_frames_received: 0
     unicast_frames_sent: 0
     sent_multiple: 0
     sent_deferred: 0
     frames_1024_to_1518_octets: 0
     frames_1519_to_max_octets: 0
     good_octets_sent: 3056

NOTES

  • FEC is supported only on SFP ports of 10G speed and higher.

Network Configurations

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