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QFX5120 Port Channel to Cisco 2350 Link Flapping

  • 1.  QFX5120 Port Channel to Cisco 2350 Link Flapping

    Posted 17 days ago

    Hello, this one has me completely stumped.  I've got two QFX5120 switches in a VC that I am trying to connect to a Cisco 2350 (I know, old...) switch with a 10g port channel.  I'm using mostly fs.com optics on the Juniper, and fs and Cisco on the Cisco switch. 

    • Juniper switch, I'm using a breakout cable to four 10g cables from the 40g QSFP (these are fs.com)
    • Cisco switch I'm using both Cisco and fs.com 10g X2 SFPs  (X2-10gb-SR)
    • Configured port channel on both Cisco and Juniper using LACP

    When I plug in the breakout cable from the juniper to the Cisco using the fs.com X2 and it's configured as a port channel, the port on the Cisco switch will shut down and go in error disable because of link flapping

    When I plug in the breakout cable from the Juniper to the Cisco using the Cisco X2, and it's configured as a port channel, the port on the Cisco switch will come up fine.

    When I plug in the breakout cable from the juniper to the Cisco using the fs.com X2 and have the port configured just as a regular trunk port or a switch port, the port will stay up fine.

    I have configured a regular SFP port on the juniper and added it to the port channel group and plugged that in to the X2 port with the fs.com X2 on the Cisco and it comes up fine.

    So, It seems that the Cisco port will disable with link flapping only when I am using the breakout cable with it configured as a port channel.  I've tried all different configurations, all different spanning tree protocols, nothing changes.  And it's so odd that it'll work with Cisco X2 SFPs.  HOWEVER, it'll only work with the V02 SFP from Cisco.  I have other versions laying around, and those do NOT work.  I know the 2350s are old, and I'll probably just replace them as part of this.   But I just can't figure out what the problem is here.  Here are the configurations.   If anyone has any ideas I'd love to hear it.   Thanks!

    Cisco

    interface Port-channel20

    switchport mode trunk

    !

    interface TenGigabitEthernet0/1

     switchport mode trunk

     channel-protocol lacp

     channel-group 20 mode active

    !

    interface TenGigabitEthernet0/2

     switchport mode trunk

     channel-protocol lacp

     channel-group 20 mode active

    Juniper

    set interfaces xe-0/0/50:0 description "lag member to sdsa03-2350 te0/1"

    set interfaces xe-0/0/50:0 ether-options 802.3ad ae3

    set interfaces xe-1/0/50:0 description "lag member to sdsa03-2350 te0/2"

    set interfaces xe-1/0/50:0 ether-options 802.3ad ae3

    set interfaces ae3 description "lag to sdsa03-2350"

    set interfaces ae3 aggregated-ether-options lacp active

    set interfaces ae3 unit 0 family ethernet-switching interface-mode trunk

    set interfaces ae3 unit 0 family ethernet-switching vlan members all



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    RYAN FISHER
    [Phone]
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