See comments inline:
>-----Original Message-----
>From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of
>Paul Werner
>Sent: February 14, 2001 10:09 PM
>To: [EMAIL PROTECTED]
>Subject: Re: RE: DISTURBING: Spanning Tree Protocol Does not Work.
>
>>Okay, here's the jist of things.
>
>Big huge mondo snip...
>
>
>> So... do we have an active looped topology? I doubt it.
>> Likely, Spanning Tree's working just fine. Check the LED's on both
>> of your switches to see if you see a solid orange glow...
>
>Leigh Anne,
>
>I like your style and troubleshooting methodology. I think you
>have honed in on the root cause of the problem (pun intended :-)
>I don't have the previous day's post, but there were a few
>entries that were dead culprits as to the problem. After
>reviewing the snipped configs, I am now more convinced than
>ever. It is a loss of connectivity issue. It is true that the
>uplink ports will both need to be trunked (and only one was
>shown as trunking), but that will not fully explain the STP
>problem. if you looked at the 2nd post where all of the
>interface stats were shown, you would have noticed that on all
>of the ports that were alledged to be trunking, two of them had
>duplex and speed status unknown.
LAC: Pierre-Alex indicated he was providing statistics on all
ports that were active - not "alleged to be trunking". A quick
review of the running-config on the 2924XL showed that only
0/20 was set to actively trunk.
I did review all duplex and speed configurations on all of his
ports (and noted what VLANs each were set for). Active ports
on the 2924XL were 1, 9, 16, 20, 21, and 24. Ports 1 and 8 were
configured to be members of VLAN3. Ports 9, 16, and 24 were
configured to be members of VLAN2. That only left ports 20 and
21 - both of which were running at 100 Mbps full duplex:
FastEthernet0/20 is up, line protocol is up
Full-duplex, 100Mb/s, 100BaseTX/FX
FastEthernet0/21 is up, line protocol is up
Full-duplex, 100Mb/s, 100BaseTX/FX
(See the bottom of this email for excerpts from Pierre-Alex's
configs for these interfaces).
Fa 0/21 wasn't explicitly configured to be trunking - and a
review of the port's statistics indicated that there hadn't
been any input received on the port for 3 hours, 49 mins, 16
seconds. That meant that IF Fa 0/21 WAS in fact physically
connected to Fa 0/27 on the 1912, Fa 0/27 wasn't sending
frames. Why wouldn't it? It appeared to be functional...
It should have been sending BPDUs every 2 seconds. So... for
some reason, it wasn't communicating.
Pierre-Alex confirmed that Fa 0/21 was in fact physically
connected to Fa 0/27. The one aspect of the configuration that
wasn't kosher was that Fa 0/21 wasn't set to trunk. I asked
him to set it to trunk, and voila, spanning tree blocked
Fa 0/27 as expected.
So... I had in fact ruled out duplex and speed mismatches
between the "trunking" ports - so I knew that wasn't the
cause.
By the way, thanks for the compliment on my troubleshooting
skills. I personally really enjoyed Pierre-Alex's scenerio
and I must say, my knowledge of Spanning Tree and switching
was really challenged during this exercise. Took me a while
to pick through everything, but my spanning tree
troubleshooting skill-set increased significantly as a result
of this exercise!
Thanks to Paul Borghese for maintaining this list for these
many months. He's really the one responsible for all of us
having this opportunity to learn from stuff like this...
-- Leigh Anne
>That is a dead ringer for this sort of dilemma. Always hard
>code your duplex and speed settings for trunks. I cannot think
>of a good reason not to, and lots of good reasons against.
>If you check the last config posted, you will note that the
>speed and duplex were not hard coded.
>
>HTH,
>
>Paul Werner
----- ON THE 1912
FastEthernet 0/26 is Enabled
Hardware is Built-in 100Base-TX
Duplex/Flow Control setting: Auto-negotiate
Auto-negotiation status: Full duplex
Receive Statistics Transmit Statistics
--------------------------- -----------------------------
Frames filtered 18511 Single collisions 0
Runt frames 0 Multiple collisions 0
No buffer discards 0 Excessive collisions 0
Queue full discards 0
Errors: Errors:
FCS errors 0 Late collisions 0
Alignment errors 0 Excessive deferrals 0
Giant frames 0 Jabber errors 0
Address violations 0 Other transmit errors 0
FastEthernet 0/27 is Enabled
Duplex/Flow Control setting: Auto-negotiate
Auto-negotiation status: Full duplex
Receive Statistics Transmit Statistics
--------------------------- -----------------------------
Frames filtered 0 Single collisions 0
Runt frames 0 Multiple collisions 0
No buffer discards 0 Excessive collisions 0
Queue full discards 0
Errors: Errors:
FCS errors 0 Late collisions 0
Alignment errors 0 Excessive deferrals 0
Giant frames 0 Jabber errors 0
Address violations 0 Other transmit errors 0
---- ON THE 2924XL
FastEthernet0/1 is up, line protocol is up
Duplex setting unknown, Unknown Speed, 100BaseTX/FX
FastEthernet0/9 is up, line protocol is up
Duplex setting unknown, Unknown Speed, 100BaseTX/FX
FastEthernet0/16 is up, line protocol is up
Half-duplex, 10Mb/s, 100BaseTX/FX
FastEthernet0/20 is up, line protocol is up
Full-duplex, 100Mb/s, 100BaseTX/FX
FastEthernet0/21 is up, line protocol is up
Full-duplex, 100Mb/s, 100BaseTX/FX
Last input 03:49:16, output 00:00:01, output hang never
FastEthernet0/24 is up, line protocol is up
Half-duplex, 100Mb/s, 100BaseTX/FX
C2924XL#sh vlan
VLAN Name Status Ports
---- ---------- --------- ----------------------------
1 default active Fa0/2, Fa0/3, Fa0/4, Fa0/5,
Fa0/6, Fa0/7, Fa0/10, Fa0/11,
Fa0/12, Fa0/13, Fa0/14, Fa0/15,
Fa0/17, Fa0/18, Fa0/19, Fa0/21,
Fa0/22, Fa0/23
2 VLAN_A active Fa0/9, Fa0/16, Fa0/24
3 VLAN_B active Fa0/1, Fa0/8
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