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[EX] When using 1 Gigabit SFP optics on the uplink module in EX4300 devices, the interface does not come up

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Article ID: KB34060 KB Last Updated: 01 Aug 2019Version: 1.0
Summary:

When using 1 Gigabit SFP optics on the uplink module in EX4300 devices, the uplink interface may not come up and manual intervention may be required to bring up the interface.

This article gives the cause for the interface to not come up and the steps to resolve the problem.

 

Symptoms:

On the uplink modules in an EX4300 switching device, when using 1 ​Gigabit optics (SFP-T​), the interface may not come up.

{master:0}
root@EX4300-1> show configuration interfaces ge-0/2/0 
description "to EX4300-2";
unit 0 {
    family inet {
        address 10.10.10.1/32;
    }
}

{master:0}
root@EX4300-2> show configuration interfaces ge-0/2/0 
description "to EX4300-1";
unit 0 {
    family inet {
        address 10.10.10.2/32;
    }
}

{master:0}
root@EX4300-1> show interfaces ge-0/2/0 terse    
Interface               Admin Link Proto    Local                 Remote
ge-0/2/0                up    down
ge-0/2/0.0              up    down inet     10.10.10.1          --> 0/0

{master:0}
root@EX4300-2> show interfaces ge-0/2/0 terse    
Interface               Admin Link Proto    Local                 Remote
ge-0/2/0                up    down
ge-0/2/0.0              up    down inet     10.10.10.2          --> 0/0

 

Cause:

By default, the 1 Gig optics ​have auto-negotiation enabled and this might cause the Packet Forwarding Engine (PFE) to drop the connection between the two links because the other side connected to the uplink interface is not set to auto-negotiate. This problem is seen on the SFP-T optics:

{master:0}
root@EX4300-1> show chassis pic fpc-slot 0 pic-slot 2    
FPC slot 0, PIC slot 2 information:
  Type                             4x 1G/10G SFP/SFP+
  State                            Online    
  PIC version                  3.2
  Uptime                         3 days, 15 hours, 23 minutes, 27 seconds

PIC port information:
                         Fiber                    Xcvr vendor       Wave-    Xcvr
  Port Cable type        type  Xcvr vendor        part number       length   Firmware
  0    GIGE 1000T        n/a   Methode Elec.      SP7041-M1-JN      n/a      0.0   
  2    GIGE 1000T        n/a   FINISAR CORP.      FCLF8521P2BTL-J3  n/a      0.0   

{master:0}
root@EX4300-1> show interfaces ge-0/2/0 
Physical interface: ge-0/2/0, Enabled, Physical link is Down
  Interface index: 744, SNMP ifIndex: 619​

 

Solution:

Disable auto-negotiation and hard code the link speed to 1 Gigabit as shown below:

set interfaces ge-x/y/z speed 1g
set interfaces ge-x/y/z ether-options no-auto-negotiation 

{master:0}[edit]
root@EX4300-1# set interfaces ge-0/2/0 speed 1g 

{master:0}[edit]
root@EX4300-1# set interfaces ge-0/2/0 ether-options no-auto-negotiation 

{master:0}[edit]
root@EX4300-1# show | compare 
[edit interfaces ge-0/2/0]
+   speed 1g;
+   ether-options {
+       no-auto-negotiation;
+   }

{master:0}[edit]
root@EX4300-1# commit 
configuration check succeeds

root@EX4300-1# run show interfaces terse ge-0/2/0 
Interface               Admin Link Proto    Local                 Remote
ge-0/2/0                up    up
ge-0/2/0.0              up    up   inet     10.10.10.1          --> 0/0

 

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