[c-nsp] Nexus Blocking Single Port?

Nick Cutting ncutting at edgetg.co.uk
Thu Jan 28 12:06:38 EST 2016

>From cisco to other vendor - (and cisco -> cisco Small BUS)

always make sure that Vlan1 is allowed on any trunk links, as they often expect the BPDU's on this Vlan.  Check that the Juniper doesn't think its ALSO the root.

-----Original Message-----
From: cisco-nsp [mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Crist J. Clark
Sent: 28 January 2016 17:04
To: cisco-nsp at puck.nether.net
Subject: [c-nsp] Nexus Blocking Single Port?

I am seeing some STP wierdness from a Nexus 9396 (surprise, surprise, I know).

I can't figure out why it's blocking one VLAN on a trunk to a Juniper switch,

scea-phx-core1# sh span vl 3013

  Spanning tree enabled protocol rstp
  Root ID    Priority    64453
             Address     0023.04ee.be01
             This bridge is the root
             Hello Time  2  sec  Max Age 20 sec  Forward Delay 15 sec

  Bridge ID  Priority    64453  (priority 61440 sys-id-ext 3013)
             Address     0023.04ee.be01
             Hello Time  2  sec  Max Age 20 sec  Forward Delay 15 sec

Interface        Role Sts Cost      Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
Eth1/23          Back BLK 2         128.279  P2p 

I don't understand a lot of things going on here. It claims to be root, but then it's blocking ports? And how can you have a backup when this is the only port on the VLAN?
Crist J. Clark
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