[c-nsp] Nexus 7018 spanning tree and unicast flooding

[Prashanth kumar]

Quimm,

Spanning tree type is normal for all the ports connected to downstream
switched.

spanning-tree port type normal

-Thanks
Prashanth

On Mon, Jun 27, 2011 at 11:28 AM, Quinn Snyder <snyderq at gmail.com> wrote:

> prashanth --
>
> i see that you have all ports as 'network' ports. i assume this is
> done by invoking
>
> spanning-trew port type network
>
> under the interface configuration stanza or so. in n7k land, this
> invokes a feature called 'bridge-assurance' and it must be explicitly
> enabled on the other end. it is a feature that can only be enabled
> globally on n7k and is enabled by default if you run any vpc services
> on n7k.
>
> that being said -- your issue may be caused by this configuration
> statement. bridge-assurance is only supported on certain versions of
> c6k, so i'd say that you have to change this. [0]
>
> please set all ports that dont have bridge-assurance on both ends to
> the following
>
> spanning-tree port type normal
>
> and see if this solves your problem.
>
> regards,
> q.
>
> [0] https://supportforums.cisco.com/thread/2000819
>
> -= sent via ipad. please excuse brevity, spelling, and grammar =-
>
> On Jun 27, 2011, at 11:05, Prashanth kumar <smarni7468 at gmail.com> wrote:
>
> > I am trying to troubleshoot a issue with  spanning tree topology change
> and
> > unicast flooding during the topology change which I have not seen in
> 6500.
> > I am new to nexus series.
> >
> > +----------+                            +-------------+
> > |              |                             |                |
> > | Root     |                             | Secondry |
> > | SW1     |------------------------| Root        |
> > |              |------------------------| SW2       |
> > +----------+                            +------------+
> >     |                                      /
> >     |                                 /
> >     |                             /
> >     |                 span blocked
> > +-------------------/---+
> > |  Access Switch   |
> > |                            |
> > +----------------------+
> >
> > We have a simple topology of two Nexus 7018  aggregation routers in DC
> and
> > access-switches connected to two of them as shown above. There are
> multiple
> > VLAN's trunked to the access  switches.  All vlans are trunked between
> Nexus
> > switch as well.  The Access swtich connection to
> > second 7018 is blocked.  We run PRSTP+ and all ports on core switch are
> type
> > network.  The issue we have is when ever we bring up a new port  or port
> > state changes on 7018 there is TCN generated and both the switch flush
> the
> > cam table and it takes about 15 to 30 second to re-learn the new mac.
> during
> > this time we see lot of unicast flooding on all the switches/load
> balancer
> > which are connected. Is this a limitation on Nexus 7000 or is this normal
> > behavior. I have not seen this on 6500.
> >
> > Thanks you in advance
> >
> >
> > PK
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