Breakout ports

Breakout functionality is supported on several platforms that run SR Linux. On SR Linux, breakout ports are named using the following format:

ethernet-slot/port/breakout-port

For example, if interface ethernet-1/3 is enabled for breakout mode, its breakout ports are named as follows:

  • ethernet-1/3/1

  • ethernet-1/3/2

  • ethernet-1/3/3

  • ethernet-1/3/4

The following table lists breakout support for SR Linux platforms.

Table 1. Breakout support for SR Linux platforms
Platform Port type Breakout support Notes
7215 IXS-A1 Not supported on any ports
7220 IXR-D1 Not supported on any ports
7220 IXR-D2 Not supported on any ports
7220 IXR-D3

4x10G and 4x25G

 Supported on ports 3-33
7220 IXR-D3L

2x50G, 4x10G, and 4x25G

 Supported on ports 1-31
7220 IXR-H2 Not supported on any ports
7220 IXR-H3

4x10G, 2x100G, 4x100G, and 2x200G

 Supported on ports 3-34
7220 IXR-H4 4x100G and 2x200G Supported on ports 1-64
7220 IXR-D4 4x100G, 4x25G, and 4x10G Supported on ports 29-32
4x10G and 4x25G Supported on ports 9, 23-27
7220 IXR-D5 4x10G, 4x25G, 2x100G, 4x100G, and 2x200G Supported on ports 1-32
7250 IXR-6/10 Not supported on any ports
7250 IXR-6e/10e 60p QSFP28 IMM 4x25G and 4x10G Supported but with port group restriction See Port group restriction for 7250 IXR-6e/10e
7250 IXR-6e/10e 36p QSFPDD IMM 4x100G, 2x100G, 4x25G, and 4x10G Supported on all ports
7250 IXR-X1b 4x25G and 4x10G Supported on ports 1-24 with port group restriction See Port group restriction for 7250 IXR-X1b
4x100G, 4x25G, and 4x10G Supported on ports 25-36
7250 IXR-X3b 4x100G, 4x25G, and 4x10G Supported on all ports
7730 SXR-1d-32D QSFP28 4x10G and 4x25G Supported but with port group restriction See Port group restriction for 7730 SXR-1d-32D QSFP28
7730 SXR-1d-32D QSFPDD 4x100G, 4x25G, and 4x10G Supported on ports 17-20
7730 SXR-1x-44S SFPDD Not supported on any ports
7730 SXR-1x-44S QSFPDD 4x100G, 4x25G, and 4x10G Supported on ports 21, 22, 43, 44

Port group restriction for 7250 IXR-6e/10e

On the 7250 IXR-6e/10e platform, with 60 QSFP28 IMM, breakout as 4x25G or 4x10G is supported on ports 9, 12, 15, 18, 21, 24, 26, 27, 29, 30, 32, 35, 38, 39, 41, 42, 45, and 48. For the port groupings in the following table, only the higher-numbered port supports breakout mode. If the higher numbered port is to be configured for breakout mode, then the lower numbered port should not be configured. If both ports are configured, then the lower-numbered port takes precedence and the higher number port shall be operationally down with reason unsupported-breakout-port.

Table 2. Restricted 4x25G and 4x10G port pairs on 7250 IXR-6e/10e

8, 9

20, 21

11, 12

23, 24

14, 15

44, 45

17, 18

47, 48

Port group restriction for 7250 IXR-X1b

For the QSFP28 ports on the 7250 IXR-X1b platform, the following port groups exist: [n, n+1, n+2, n+3] where n = 1, 5, 9, 13, 17, 21. Breakout for 4x25G or 4x10G is only supported on ports n+1 and n+3.

When initially configuring a port with a breakout configuration or port speed that does not already exist on another configured port within the same group, then a link flap and traffic hit may occur on other ports within the same group.

When the breakout configuration or port speed is changed for a port in a group, then a link flap and traffic hit may occur on other ports within the same group.

If port n+1 within the group is configured for breakout, then port n cannot be configured. In addition, if port n+1 is configured for breakout and port n+3 is configured without breakout, then port n+2 may only be configured with the same speed as port n+3. If port n+3 within the group is configured for breakout, then port n+2 cannot be configured. If port n+3 is configured for breakout and port n+1 is configured without breakout, then port n may only be configured with the same speed as port n+1.

Port group restriction for 7730 SXR-1d-32D QSFP28

On the 7730 SXR-1d-32D QSFP28 platform, breakout and 40G are only supported on odd-numbered ports.

Ports 5-16 and 29-32 have a pairing between an odd numbered port n and the next higher even-numbered port (n+1). If the odd numbered port is enabled and configured for 40G, 4x10G or 4x25G, the even-numbered port cannot be enabled.

For the 4-port groupings [1-4], [21-24], and [25-28]: if either of the odd-numbered ports within a group is enabled and configured for 40G, 4x10G, or 4x25G, then the other odd-numbered port in the same group may only be enabled if it is configured for one of 40G, 4x10G, or 4x25G (can differ between the odd ports) and neither of the two even-numbered ports within the same group can be enabled.

Feature considerations for breakout connectors

When an interface is configured for breakout mode, it operates as a component of a breakout connector, not an Ethernet port. Some features that are configurable on an Ethernet port do not apply to a breakout connector or breakout port.

The following table lists considerations that apply to breakout connectors and component breakout ports.

Table 3. Considerations for breakout connectors and ports
Configuration or state Breakout connector considerations Breakout port considerations
admin-state

Allowed

admin-state disable causes all breakout ports to be shut down. In this case:

  • The connector shows oper down with reason: port-admin-disabled.
  • The connector's transceiver shows oper down with reason: port-disabled.
  • The individual breakout ports show oper down with reason: connector-down (if the breakout port is not disabled as well).
  • The transceiver of the individual breakout ports show oper-down with reason: connector-transceiver-down. Reading tx-laser from state returns false even if configured true.

Allowed

admin-state disable causes the individual breakout port to be shut down. In this case:

  • The connector oper-state is not impacted.
  • The connector's transceiver oper state is not impacted.
  • The individual breakout port shows oper-down with reason: port-admin-disabled
  • The transceiver of the individual breakout port shows oper-down with reason: port-disabled. (In this case reading tx-laser from state returns false.)
description Allowed Allowed
mtu Not allowed Allowed
loopback-mode Not allowed Allowed
vlan-tagging Not allowed Allowed
ifindex Allocated
interface/oper-state Populated Populated
interface/oper-down-reason

Populated

Populated

  • connector-down is shown when the breakout port is down because the parent connector has been administratively disabled.
last-change Follows changes in oper-state Follows changes in oper-state
subinterface Not allowed Allowed
lag Not allowed Not allowed
qos Not allowed Allowed
sflow Not allowed Allowed
queue-stats Not populated Populated
statistics Not populated Populated
traffic-rate Not populated Populated
transceiver

transceiver oper-down-reason can be any of the following:

  • not-present (nothing reported by device manager)
  • read-failure
  • checksum-failure
  • unknown-transceiver
  • unsupported-breakout (if num-channels x channel-speed is not compatible with the overall speed)
  • port-disabled

The following are not configurable:

  • tx-laser
  • ddm-events
  • forward-error-correction

Only transceiver oper-state and transceiver oper-down-reason are displayed. The transceiver oper-down-reason can be any of the following:

  • not-present (nothing reported by device manager)
  • tx-laser-disabled (the tx-laser has been configured to false by the user)
  • port-disabled (the associated port has been disabled; for example, admin-disabled)
  • connector-transceiver-down (the transceiver associated with the connector is operationally down)

Configuration is allowed, with effects as described below:

  • tx-laser affects only the individual breakout port. If the installed transceiver supports per-channel disabling of the TX laser then tx-laser = false causes the breakout port to be oper down. If the installed transceiver does not support per-channel disabling of the TX laser, then the breakout port remains oper up and info from state displays tx-laser=true.
  • If ddm-events = true for any breakout port, then the system generates warning logs for temperature and voltage of the overall transceiver/connector.
  • if ddm-events = false for any breakout port, then the system suppresses warning logs for input-power, output-power and laser-bias-current for that specific port/laser.
  • The forward-error-correction algorithm applies only to the individual breakout port.
ethernet/aggregate-id Not allowed Allowed
ethernet/auto-negotiate Not allowed Allowed
ethernet/duplex-mode Not allowed Allowed
ethernet/flow-control Not allowed Allowed
ethernet/lacp-port-priority Not allowed Allowed
ethernet/port-speed Not allowed Not allowed.

The speed of the breakout port is determined by the channel-speed setting configured for the breakout connector.
ethernet/reload-delay Not allowed Allowed
ethernet/hold-time Not allowed Allowed
ethernet/hw-mac-address Not populated Allocated and displayed
ethernet/standby-signaling Not allowed Allowed
ethernet/storm-control Not allowed Allowed
ethernet/statistics Not populated Populated

Configuring breakout mode for an interface

To enable breakout ports, you enable breakout mode for an interface and configure breakout ports for the interface.

The following is an example of configuring an interface for breakout-mode and enabling breakout ports on the interface.

--{ candidate shared default }--[  ]--
# info interface ethernet-1/3*
    interface ethernet-1/3 {
        admin-state enable
        description "Breakout connector"
        breakout-mode {
            num-breakout-ports 4
            breakout-port-speed 25G
        }
    }
    interface ethernet-1/3/1 {
        admin-state enable
        description "Breakout port 1"
        subinterface 1 {
            admin-state enable
            ipv4 {
                admin-state enable
                address 192.168.12.1/30 {
                }
            }
        }
    }
    interface ethernet-1/3/2 {
        admin-state enable
        description "Breakout port 2"
        subinterface 1 {
            admin-state enable
            ipv4 {
                admin-state enable
                address 192.168.12.5/30 {
                }
            }
        }
    }
    interface ethernet-1/3/3 {
        admin-state enable
        description "Breakout port 3"
        subinterface 1 {
            admin-state enable
            ipv4 {
                admin-state enable
                address 192.168.12.9/30 {
                }
            }
        }
    }
    interface ethernet-1/3/4 {
        admin-state enable
        description "Breakout port 4"
        subinterface 1 {
            admin-state enable
            ipv4 {
                admin-state enable
                address 192.168.12.13/30 {
                }
            }
        }
    }