Juniper Config Commit causes Cisco Etherchannels to go into err-disable state

Wed Apr 18 17:41:39 UTC 2018

Not sure exactly what your environment looks like, but we encountered
something similar when trunking Cisco-DELL and Cisco-Juniper switches.
We run RSTP on DELL and Juniper switches, but RPVST+ on Cisco. In the
beginning we just allow those VLANS we need between Cisco-DELL/Juniper
switches, then encountered unexpected err-disable / link drop things.
Later we figured Cisco always carry default VLAN (VLAN-1) untagged
through trunk ports. Hence we manually "explicitly" add/allow
Native-VLAN-1 (untagged) on all trunk ports in all switches. Problem
solved.

On Fri, Apr 6, 2018 at 11:59 AM, Mark Milhollan <mlm at pixelgate.net> wrote:
> Sounds like the Juniper is leaking a "default" BPDU as it resets the
> various internal chip configurations, which the Cisco receives thus
> triggering the err-disable.
>
>
> /mark

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Michel~