[EMAIL PROTECTED] wrote:
Hi,
"logging event link-status" (or "spanning-tree logging" was not configured
on any switch so don't know if any of the ports went up or down.
no syslog either. what about the uptime of the switches...did one or
more fail due to loss of power?
are you running PVST?
alan
Hi Alan,
It's Rapid-PVST. Thanks for your reply. I've since found out some other
information (SW2 was reloaded) that makes things a bit confusing to
explain the entire situation here, and I wouldn't expect anyone here to
sit through my entire timeline of events :)
It would be helpful if someone could answer just the first question,
regarding the meaning of "topology changes" under "sh span vlan x detail".
Root port is 47 (GigabitEthernet1/47), cost of root path is 14
Topology change flag not set, detected flag not set
Number of topology changes 11 last change occurred 2d00h ago
from GigabitEthernet1/47
That is, what type of packet (TCN, TCA, BPDU with TC set) or event
(missing root BDPU, transition to fowarding) causes this counter to
increment (and record the port underneath).
And, how, after a spanning-tree convergance/event (caused by the
reloading of SW2) the ports listed under the topology change can end up
pointing at each other (as in this example):
SW7 >------< SW8
| X
| |
/|\ |
SW3 SW4 (R)
| \|/
| |
/|\ |
SW1 -------< SW2
SW4 is the root switch.
X is a blocking port
Arrows represent the port that received a topology change (all at the
same time) listed under "sh spantree vlan X detail".
What happened to make the ports listed on SW7 and SW8 point at each
other? I can envisage this scenario:
SW2 is reloaded causing the blocking port on SW8 to go forwarding. After
SW2 is reloaded the port goes back to blocking, and SW8 issues a TCN.
But this would mean that SW8 logged the _outgoing_ port it sent the TCN
on, while all the others logged the report that _received_ the TCN on.
I can't find any information to support this hyposis. The name "topology
change" also suggests that it could be looking at the TC bit in BPDUs,
not the TCNs.
If anyone can explain this to me I will be very grateful,
Sam
(I'm actually beginning to suspect that SW2 continued to forward BPDUs
but not HSRP packets and knowledge of how the counters work should help
me work this possibility).
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