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Gigabit Ethernet Interfaces

Learn about speed and autonegotiation on Gigabit Ethernet interfaces, and how to configure speed and autonegotiation.

Speed on Gigabit Ethernet Interfaces

Configure Interface Speed on Switches

On 1/10GbE-capable SFP interfaces, the duplex is always full. Also, the speed matches the inserted optic. These interfaces support either 1GbE or 10GbE SFP optics. See Configure Speed at Interfaces Level.

Configure Speed on QFX5100-48T Switches

See Configure Port Speed at Chassis Level and Interface Level to configure speed.

For information about speed support, see speed (Ethernet).

Table 1 provides QFX5100-48T details and description.

Table 1: QFX5100-48T Details and Description

Detail

Description

Duplex Mode

Full duplex

The guidelines for configuring speed on QFX5100-48T switch are as follows:

  • If the speed on the switch is set to 10-Gbps or auto, the switch advertises all the speeds.

  • If the speed on the switch is set to 1-Gbps, the switch advertises 1-Gbps and 100-Mbps.

  • If you have configured the speed to 100 Mbps on the switch, then you must also configure the speed as 100 Mbps and duplex to full duplex on the link partner.
Table 2: Configure Speed

Configure Speed

Use Configuration

To configure a particular speed, mention the speed.

For a port to only advertise a specific speed, start with a specific speed. It is mandatory that you:

  • Enable the autonegotiation option.

  • Configure the interface with a specific supported speed.

set interfaces xe-0/0/0 ether-options auto-negotiation 
set interfaces xe-0/0/0 speed speed

For example to configure 1-Gbps speed, execute the following command:

set interfaces xe-0/0/0 ether-options auto-negotiation 
set interfaces xe-0/0/0 speed 1g

Autonegotiation on Gigabit Ethernet Interfaces

Autonegotiation Overview

Learn about autonegotiation, its configuration, and key points about autonegotiation on EX and QFX Series Switches.

On Juniper EX Series switches, autonegotiation is enabled by default on GbE interfaces to automatically negotiate speed and duplex settings with the link partner. You can explicitly configure autonegotiation or disable it if you set the speed and duplex manually. When autonegotiation is disabled, you must configure the link speed (10 or 100 Mbps) and duplex mode explicitly.

Key points for EX Series Switches autonegotiation:

  • Enabled by default on Gigabit Ethernet copper interfaces.
  • If disabled, speed and duplex must be manually set.
  • You can configure autonegotiation with options for remote fault detection.
  • On fiber interfaces operating at 1 Gbps, autonegotiation is enabled by default but can be disabled on some ACX routers (not EX switches).
  • Use Junos CLI commands under the interface's ether-options hierarchy to enable or disable autonegotiation.

For example, to enable autonegotiation on an interface:

To disable autonegotiation and set speed manually:

You can verify the autonegotiation status and negotiated speed with the show interfaces ge-0/0/0 extensive command.

For QFX5100 switches, autonegotiation is also enabled by default on 10-Gigabit Ethernet interfaces and cannot be disabled. If you configure a 100 Mbps speed on the link partner, you must configure the QFX5100 port speed to 10 Gbps, 1 Gbps, or auto to maintain compatibility.

Autonegotiation Support for EX4300-48MP Switches

The 4-port 1-Gigabit Ethernet/10-Gigabit Ethernet uplink module (EX-UM-4SFPP-MR) on EX4300-48MP switches supports 1-Gbps speed. You do not need to explicitly configure 1-Gbps speed on the uplink module as it automatically identifies the installed 1-Gigabit SFP transceivers and creates the interface accordingly.

If both Energy Efficient Ethernet (EEE) and 100 Mbps speed are configured on a rate-selectable mge port, the port operates only at 100 Mbps speed but EEE is not enabled on that port. Note that EEE is supported only on mge interfaces that operate at 1 Gbps, 2.5 Gbps, 5 Gbps, and 10 Gbps speeds.

On EX4300-48MP, the status LED of 1 GbE uplink module port is solid green (instead of blinking green) because of a device limitation. However, device functionality does not change.

Table 3 summarizes the autonegotiation and half duplex support on EX4300-48MP switches.

Table 3: Autonegotiation and Half-Duplex Support for EX4300-48MP Switches

Port Numbers

Interface Name

Autonegotiation Supported (YES/NO)?

Half Duplex Supported (YES/NO)?

PIC 0 PORTS 24-47

mge

Yes. Speed supported (10 Gbps/5 Gbps/2.5 Gbps/1 G/100 Mbps)

No

PIC 2 PORT 0 – 3 (Uplink ports)

xe

No

No

PIC 0 PORTS 0 – 23

ge

1 G/100 Mbps/10 Mbps

Yes, but you cannot configure half duplex on EX4300-48MP switches. If the link partner is half duplex and capable of autonegotiating half duplex, then these ports can work a half duplex.

PIC 2 PORT 0 - 3

Uplink 4x10G

No. Based on inserted transceiver, port is ge for 1 G SFP and xe for 10 GbE SFP.

No

PIC 2 PORT 0, 1

Uplink 2x40G

No

No

Autonegotiation Support for EX4400 Switches

Table 4: Autonegotiation and Half-Duplex Support for EX4400 Switches

Interface Name

Autonegotiation Supported (YES/NO)?

Half Duplex Supported (YES/NO)?

xe

No

No

ge

1 G/100 Mbps/10 Mbps

Yes, but you cannot configure half duplex on EX4400 switches. If the link partner is half duplex and capable of autonegotiating half duplex, then these ports can work a half duplex.

mge (PIC 0)

Yes. Speed supported (10 Gbps/5 Gbps/2.5 Gbps/1 Gbps/100 Mbps)

No

2x40G, 2x100G (PIC 1)

No

No

Uplink 1x100G, 4x10G, and 4x25G (PIC 2)

No. Based on inserted transceiver, port is ge for 1 G SFP and xe for 10 GbE SFP.

No

Autonegotiation Support for EX4100 Switches

Table 5: Autonegotiation and Half-Duplex Support for EX4100 Switches

Interface Name

Autonegotiation Supported (YES/NO)?

Half Duplex Supported (YES/NO)?

mge

Yes. Speed supported (10 Gbps/5 Gbps/2.5 Gbps/1 Gbps/100 Mbps)

No

xe

No

No

ge

1 Gbps/100 Mbps/10 Mbps

Yes, you can configure half duplex on EX4100 switches.

Autonegotiation Support for EX4600-40F, QFX5110-48S, and QFX5100-48S with JNP-SFPP-10GE-T Transceiver

The interfaces on the JNP-SFPP-10GE-T transceivers appear based on the speed (100 Mbps, or 1 Gbps, or 10 Gbps) configured using the set interfaces interface-name speed speed command at the remote end.

For information about platforms support, see Hardware Compatibility Tool.

Table 6 discusses EX4600-40F, QFX5110-48S, and QFX5100-48S switches with JNP-SFPP-10GE-T transceiver details.

Table 6: EX4600-40F, QFX5110-48S and QFX5100-48S Switches with JNP-SFPP-10GE-T Transceiver Details and Description

Details

Description

EX4600-40F with JNP-SFPP-10GE-T transceiver

 Interface created—xe or mge depending on the Junos version.

QFX5110-48S and QFX5100-48S switches with JNP-SFPP-10GE-T transceiver

Interface created - ge interface.

On QFX5110-48S and QFX5100-48S, the ge interface supports 100 Mbps, 1 Gbps, and 10 Gbps speeds, which can be configured using the speed configuration statement.

Use the set interfaces ge-0/0/0 speed (100M|1G|10G) command to configure the speed and autonegotiation.

EX4600-40F, QFX5110-48S and QFX5100-48S switches with other transceivers

Interface created - ge or the xe.

Duplex Mode

Full duplex

Viewing Media Specific Information

Execute the show interfaces media command to view the media-specific information. In the output of show interfaces name media, the output field speed displays the speed that is configured for the mge interface (with a default of 10 Gbps). The configured speed signifies the highest speed that the JNP-SFPP-10GE-T transceiver is capable of working at. You should enable autonegotiation for the transceiver unless it works in 100 Mbps. In 100 Mbps speed, the transceiver can use the parallel detect capability. This capability enables the transceiver to detect when the link partner is in forced 100BASE-Tx mode and bring the link up. The speed displayed under the Link partner denotes the actual speed at which the link is working. The Link partner speed is dynamic and displays the highest speed that both ends have negotiated and can work at.

When the interface is configured with a particular speed, it means that the transceiver can support connection to a peer at rates lesser than or equal to the configured speed, as shown in Table 7:

Table 7: Interface Speed Based on Configured Speed and Remote End Speed

Configured Speed

The remote end speed of the interface (in the up state)

10G

10G, 1G, and 100M

1G

1G and 100M

100M

100M

Autonegotiation Support for QFX5120-48Y with JNP-SFPP-10GE-T Transceiver

For information about platforms support, see Hardware Compatibility Tool.

Table 8 discusses QFX5120-48Y with JNP-SFPP-10GE-T transceiver details.

Table 8: QFX5120-48Y with JNP-SFPP-10GE-T Transceiver Details and Description

Details

Description

Supported speeds

10 Gbps and 1 Gbps

Default speed: 10 Gbps (with or without JNP-SFPP-10GE-T transceiver connected)

If the peer does not support 10-Gbps speed, then the link will be down.

Duplex Mode

Full duplex

Table 9 configure 1-Gbps and 10-Gbps speeds on QFX5120-48Y with JNP-SFPP-10GE-T transceiver.

Table 9: Configure and Delete 1-Gbps Speed

Configure Speed.

Description

1 Gbps

Use the set chassis fpc 0 pic 0 port port-number speed 1G command. Due to hardware limitations, you can configure the port-number value only in multiples of four, starting from port 0. You must also configure sets of four consecutive ports (for example, 0-3, 4-7, and so on) to operate at the common speed.

On QFX5120 switch, mge interfaces are not supported due to hardware limitations.

To revert to 10-Gbps speed (after setting 1 Gbps speed.

Delete the 1G speed configuration.

Autonegotiation on QFX5100-48T Switches

Table 10: QFX5100-48T Details and Description

Details

Description

Duplex Mode

Full duplex

Autonegotiation

The autonegotiation option is to negotiate the speeds.

10 Gbps, 1 Gbps, 100 Mbps-By default, autonegotiation is enabled.

The guidelines for autonegotiation on QFX5100-48T switches are as follows:

  • If the link partner is set to autonegotiate at 100 Mbps, then you must configure the speed to 10-Gbps, 1-Gbps or auto on QFX5100-48T switch.

  • The no-auto-negotiation statement does no action. Hence, we recommend not to use the no-auto-negotiation statement.

Table 11: Configure Speed and Autonegotiation
Configure Speed/Autonegotiation Use Configuration

To configure a particular speed, mention the speed.

For a port to only advertise a specific speed, start with a specific speed.

It is mandatory to:

  • Enable the autonegotiation option

  • Configure the interface with a specific speed.

set interfaces xe-0/0/0 ether-options auto-negotiation 
set interfaces xe-0/0/0 speed speed

For example to configure 1-Gbps speed, execute the following command:

set interfaces xe-0/0/0 ether-options auto-negotiation 
set interfaces xe-0/0/0 speed 1g

To enable autonegotiation and advertise all speeds.

With or without below, QFX5100-48T interface support autonegotiation to one of either 10 Gbps and 1 Gbps.

set interfaces xe-0/0/0 ether-options auto-negotiation
set interfaces xe-0/0/0 speed auto

This configuration does not change any functionality. If the speed is set to 10 Gbps, the interface still operates as auto, and advertises 10 Gbps/1 Gbps/100 Mbps.

When you configure a port using the speed auto option, the port deletes the last configured speed. The port then re-initializes and advertises all supported speeds to the connected device.