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Auto-Negotiation issues With Cisco and other Devices

  • 1.  Auto-Negotiation issues With Cisco and other Devices

    Posted 11-24-2020 08:50
    Hello,

    we are using qfx5120-48y with Junos 19.4R2-S1.2

    We got some Auto-negotiation issues with some switches.  At Juniper side, Auto-neg is enabled on all Interfaces so on cisco. But the 1G SFP Link does not come up at Cisco side. 

    At Juniper i see the Link ist up but at cisco side not. If i change at cisco side to no-auto-negotiation the link comes up.

    Config Juniper:
    traceoptions {
        flag all;
    }
    speed auto;
    ##
    ## 'ether-options' was inherited from group 'AUTO-NEG'
    ##
    ether-options {
        ##
        ## 'auto-negotiation' was inherited from group 'AUTO-NEG'
        ##
        auto-negotiation;
    }
    unit 0 {
        family ethernet-switching {
            interface-mode access;
            vlan {
                members 926;
            }
        }
    }
    
    {master:0}[edit]
    ​
    
    show interfaces ge-0/0/5
    Physical interface: ge-0/0/5, Enabled, Physical link is Up
      Interface index: 672, SNMP ifIndex: 576
      Link-level type: Ethernet, MTU: 1514, 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: Disabled, Auto-negotiation: Enabled, Remote fault: Online, Media type: Fiber, IEEE 802.3az Energy Efficient Ethernet: Disabled, Auto-MDIX: Enabled
      Device flags   : Present Running
    

    Config at Cisco:
    sh running-config interface gigabitEthernet 4/26
    Building configuration...
    
    Current configuration : 89 bytes
    !
    interface GigabitEthernet4/26
     switchport access vlan 926
     switchport mode access
    end
    
    ​
    
    sh interfaces  gigabitEthernet 4/26
    GigabitEthernet4/26 is down, line protocol is down (notconnect)
      Hardware is Gigabit Ethernet Port, address is 0021.d824.3559 (bia 0021.d824.3559)
    


  • 2.  RE: Auto-Negotiation issues With Cisco and other Devices

     
    Posted 11-24-2020 08:55
    Hello Kev,

    I found this PR, but it does not mention if QFX5120 is affected by this. However, this is fixed on 19.4R3:
    https://prsearch.juniper.net/InfoCenter/index?page=prcontent&id=PR1423201

    Can you please upgrade to one of the mentioned releases and check if this solves your issue?

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  • 3.  RE: Auto-Negotiation issues With Cisco and other Devices

    Posted 11-24-2020 10:05
    After upgrading one leaf to  19.3R3 the problem still exist,  I can't get a link online between Juniper and Cisco with 1G LR or SR sfp with auto-neg enabled



  • 4.  RE: Auto-Negotiation issues With Cisco and other Devices

     
    Posted 11-24-2020 10:09
    Then please open a JTAC case and ask them if this PR is planned to be included for QFX5120 platform. Actually this is a Broadcom chipset issue and is fixed for QFX5100 and ACX5000 platform for sure. But QFX5120 has a different chipset than QFX5100 (Trident 3 instead of Trident 2). So maybe there is another fix necessary.

    ------------------------------
    ------------------------------
    If my answer provides the solution, please mark my post as "Accepted Solution".
    If you think my answer helps, please spend some Kudos
    ------------------------------



  • 5.  RE: Auto-Negotiation issues With Cisco and other Devices

    Posted 11-24-2020 10:12
    Hi Kev,

    as I can see from the output there is a Fiber media-type used for connecting Juniper and Cisco devices between each other, but auto-negotiation feature is used by Ethernet over copper wiring only as the fiber transceivers work on one speed only. So I'm pretty sure that auto-negotiation have not to be used in your case...

    Here is the resource that also describes this topic: Why No Auto-Negotiation for Fiber-Optic Media?

    ------------------------------
    Regards,
    Elchin
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