The customer had requested to test the knob for link speed and auto-negotiation.  We tested the knob for devices MX and PTX range and shared our results with the customer.

Link-Speed Command in AE Bundles

The `link-speed` command is used to specify the speed for member links within an Aggregated Ethernet (AE) bundle. This command has been available for over a decade and was initially used to manage member links that supported mixed rates, such as interfaces operating at both 1 Gbps and 100 Mbps. 

The `link-speed` configuration functions as an upper limit for the speed of any link added to the bundle. This setting applies to all child member interfaces within the AE bundle.

Lab Test Results

In a lab environment, a 100 Gbps member link was configured. When the `link-speed` command was set to 100, the AE bundle displayed as operational with a speed of 100 Gbps. This behaviour aligns with the expected functionality of the command.

labroot@jtac-ptx5000dc-r2007-re0# run show configuration interfaces ae30 |display set
set interfaces ae30 mtu 9216
set interfaces ae30 aggregated-ether-options minimum-links 1
set interfaces ae30 aggregated-ether-options link-speed 100g
set interfaces ae30 aggregated-ether-options lacp active
set interfaces ae30 unit 0 family inet filter input BA-IP-INPUT-FILTER
set interfaces ae30 unit 0 family inet address 29.2.12.1/24
set interfaces ae30 unit 0 family iso
set interfaces ae30 unit 0 family inet6 filter input BA-IPV6-INPUT-FILTER
set interfaces ae30 unit 0 family inet6 address 2001:4860:0:1::bf34/127
set interfaces ae30 unit 0 family mpls filter input MPLS-INPUT-FILTER
 
{master}[edit]
labroot@jtac-ptx5000dc-r2007-re0# run show interfaces et-2/0/4 | match speed
  Link-level type: Ethernet, MTU: 9216, Speed: 100Gbps, BPDU Error: None, Loop Detect PDU Error: None, Loopback: Disabled, Source filtering: Disabled,
 
{master}[edit]
labroot@jtac-ptx5000dc-r2007-re0# run show interfaces ae30 | match speed       
  Link-level type: Ethernet, MTU: 9216, Speed: 100Gbps, BPDU Error: None, MAC-REWRITE Error: None, Loopback: Disabled, Source filtering: Disabled,

When a 40G link speed is configured for an AE bundle, the bundle will go down if any member link does not support this speed. For instance, if a member link only supports 100G, it cannot be configured to 40G. As a result, the member link will be detached from the bundle, and the reason cited will be "speed mismatch." Despite the detachment, the member link will continue to display its original speed of 100G

{master}[edit]
labroot@jtac-ptx5000dc-r2007-re0# run show interfaces ae30 | match speed                        
  Link-level type: Ethernet, MTU: 9216, Speed: Unspecified, BPDU Error: None, MAC-REWRITE Error: None, Loopback: Disabled, Source filtering: Disabled,
 
{master}[edit]
labroot@jtac-ptx5000dc-r2007-re0# run show interfaces et-2/0/4 | match speed                    
  Link-level type: Ethernet, MTU: 9216, Speed: 100Gbps, BPDU Error: None, Loop Detect PDU Error: None, Loopback: Disabled, Source filtering: Disabled,
 
labroot@jtac-ptx5000dc-r2007-re0# run show interfaces ae30
Physical interface: ae30, Enabled, Physical link is Down
  Interface index: 156, SNMP ifIndex: 743
  Link-level type: Ethernet, MTU: 9216, Speed: Unspecified, BPDU Error: None, MAC-REWRITE Error: None, Loopback: Disabled, Source filtering: Disabled,
  Flow control: Disabled, Minimum links needed: 1, Minimum bandwidth needed: 1bps
  Device flags   : Present Running
  Interface flags: Hardware-Down SNMP-T


Auto Negotiation: 
Auto-negotiation is a protocol used in Ethernet networks to allow two connected devices (such as computers, switches, or routers) to automatically determine the best settings for communication. These settings typically include:

Speed: The data transfer rate (e.g., 10 Mbps, 100 Mbps, 1 Gbps, or more).
Duplex Mode: Whether the devices will use full-duplex (data can be sent and received simultaneously) or half-duplex (data can only flow in one direction at a time)

While some devices have by default auto-negotiation settings enabled, some do not. 

For PTX1K and MX:
PTX1K
Physical interface: et-0/0/0:0, Enabled, Physical link is Down
  Interface index: 145, SNMP ifIndex: 519
  Link-level type: Ethernet, MTU: 1514, LAN-PHY mode, Speed: 10Gbps, BPDU Error: None, Loop Detect PDU Error: None, Ethernet-Switching Error: None,
  MAC-REWRITE Error: None, Loopback: None, Source filtering: Disabled, Flow control: Enabled, Speed Configuration: Auto
MX
Physical interface: ge-1/0/0, Enabled, Physical link is Up
  Interface index: 275, SNMP ifIndex: 590
  Description: To server 10.85.181.5 eno2
  Link-level type: Ethernet, MTU: 1514, MRU: 1522, LAN-PHY mode, Speed: 1000mbps, BPDU Error: None, Loop Detect PDU Error: None,
  Ethernet-Switching Error: None, MAC-REWRITE Error: None, Loopback: Disabled, Source filtering: Disabled, Flow control: Enabled,
  Auto-negotiation: Enabled, Remote fault: Online
 
Below is the official document for auto-negotiation for MX devices.
 
MX: => https://www.juniper.net/documentation/us/en/software/junos/interfaces-ethernet/topics/topic-map/gigabit-ethernet-autonegotiation.html#d166e120
 
PTX10001 and PTX10003 Auto-Negotiation Configuration

Auto-negotiation is disabled by default on both the PTX10001 and PTX10003 devices. 

To enable auto-negotiation, you must manually configure it in the device configuration.

PTX 10003
 
For 100G
labroot@e04-30> show version | match :
Hostname: e04-30
Model: ptx10003-160c
Junos: 22.3X50.55-EVO
Yocto: 3.0.2
Linux Kernel: 5.2.60-yocto-standard-g9f4e024
 
labroot@e04-30> show interfaces et-0/0/0:0 extensive | match auto
 Source filtering: Disabled, Flow control: Enabled, Auto-negotiation: Disabled, Media type: Fiber
 
labroot@e04-30> show interfaces et-0/0/0:0 extensive                
Physical interface: et-0/0/0:0, Enabled, Physical link is Up
 Interface index: 1143, SNMP ifIndex: 580, Generation: 682899801184
 Link-level type: Ethernet, MTU: 1514, LAN-PHY mode, Speed: 100Gbps, BPDU Error: None, Loop Detect PDU Error: None, Ethernet-Switching Error: None, MAC-REWRITE Error: None, Loopback: Disabled,
 Source filtering: Disabled, Flow control: Enabled, Auto-negotiation: Disabled, Media type: Fiber
 Device flags  : Present Running
 Interface flags: SNMP-Traps
 CoS queues    : 8 supported, 8 maximum usable queues
 Hold-times    : Up 0 ms, Down 0 ms
 Damping       : half-life: 0 sec, max-suppress: 0 sec, reuse: 0, suppress: 0, state: unsuppressed
 Current address: cc:e1:94:81:d6:b0, Hardware address: cc:e1:94:81:d6:b0
 Last flapped  : 2024-09-26 20:26:45 PDT (02:55:11 ago)
 Statistics last cleared: Never

By default the auto-negotiation is disabled: you have to enable it by using the below command.

[edit]
labroot@e04-30# set interfaces et-0/0/0:0 ether-options auto-negotiation   
 
 
labroot@e04-30> show interfaces et-0/0/0:0 extensive | match auto   
 Source filtering: Disabled, Flow control: Enabled, Auto-negotiation: Enabled, Media type: Fiber
 
 For PTX 10001 - The Auto-negotiation is disabled as well by default.
 
 
labroot@e04-38> show version 
Hostname: e04-38
Model: ptx10001-36mr
Junos: 22.3X50.55-EVO
 
labroot@e04-38> show interfaces et-0/0/0 extensive 
Physical interface: et-0/0/0, Enabled, Physical link is Up
 Interface index: 1216, SNMP ifIndex: 515, Generation: 712964572126
 Link-level type: Ethernet, MTU: 1514, LAN-PHY mode, Speed: 100Gbps, BPDU Error: None, Loop Detect PDU Error: None, Ethernet-Switching Error: None, MAC-REWRITE Error: None,
 Loopback: Disabled, Source filtering: Disabled, Flow control: Enabled, Auto-negotiation: Disabled, Media type: Fiber
 
 
labroot@e04-38> edit    
Entering configuration mode
 
[edit]
labroot@e04-38# set interfaces et-0/0/0 ether-options auto-negotiation 
 
[edit]
labroot@e04-38# commit
 
[edit]
labroot@e04-38# run show interfaces et-0/0/0 extensive | match auto 
 Loopback: Disabled, Source filtering: Disabled, Flow control: Enabled, Auto-negotiation: Enabled, Media type: Fiber


These tests were based on particular customer requirements however, one can find the data of each product line on the Juniper Documentation page.

Even in this platform (PTX10004 and PTX10008), auto negotiation is disabled by default. To enable it we need to explicitly configure it.

root@PTX10004-re0> show interfaces et-0/0/1 | match negotia
MAC-REWRITE Error: None, Loopback: Disabled, Source filtering: Disabled, Flow control: Enabled, Auto-negotiation: Disabled, Media type: Fiber
root@PTX10004-re0# show | compare
[edit interfaces]
+ et-0/0/1 {
+ ether-options {
+ auto-negotiation;
+ }
+ }
{master}[edit]
root@PTX10004-re0# commit and-quit
{master}
root@PTX10004-re0> show interfaces et-0/0/1 | match auto
MAC-REWRITE Error: None, Loopback: Disabled, Source filtering: Disabled, Flow control: Enabled, Auto-negotiation: Enabled, Media type: Fiber