Hi,
On 03/11/2012 02:13 PM, Marki wrote:
Erik Auerswald<auerswald<at> fg-networking.de> writes:
we had to reboot one of our G3s and since then one of the port is in STP
blocking mode: show spantree stats port ge....
SID Port State Role Cost Priority
--- ---------- ---------------- ----------- -------- --------
1 ge.1.13 Discarding* Designated 200000 128
The asterisk means you want to check the reason for this port state using:
show spantree nonforwardingreason port ge.1.13
HTH
Oh indeed it does. Shame on me I didn't see that in the menu.
nonforwardingreason shows a disputed BPDU condition. Now why should that
suddenly appear after the reboot of the switch? Well, is there a command to see
where exactly that BPDU is coming from? Behind that port *should* be a private
network with another switch but no more bridging back to the main network... If
there is no built-in function I guess I'll check with a network sniffer.
Well, do you have loop protect enabled? If so, is it enabled on the port
in question? What does that other switch do with the respective BPDUs?
What kind of spanning tree is configured on that other switch?
If you do not expect any BPDUs incoming on port ge.1.13, you should
configure it as an access port (edge port) and enable spanguard to block
the port if a BPDU comes that way.
If the other switch in question sends spurious BPDUs, you might even
consider disabling STP on that port... BUT I'd rather replace (or fix)
that "other" switch.
A correct setup would have all switches in your layer 2 network
participate in the spanning tree, of course.
BTW I think it is quite strange that you have a "private network"
comprising at least one switch connected to your LAN. If this means that
some other LAN outside your control is connected to your own LAN, you
have a recipe for trouble...
To answer your question: I don't know of a command to debug incoming
BPDUs on the switch, a network sniffer would be needed to take a closer
look.
Br,
Erik
--
Dipl.-Inform. Erik Auerswald http://www.fg-networking.de/
E:[email protected] P:+49-631-4149988-0 M:+49-176-64228513
Gesellschaft für Fundamental Generic Networking mbH
Geschäftsführung: Volker Bauer, Jörg Mayer
Gerichtsstand: Amtsgericht Kaiserslautern - HRB: 3630
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