Port 0/27 on the Catalyst 1912 doesn't seem to be sending anything to Port
0/21 on the Catalyst 2924XL. If you look at my message from last night,
you'll notice that Fa0/21 hasn't been receiving input for 3 hours. If
BPDU's are sent every 2 seconds, there's some sort of communication fault
occurring with the port.
Since the Catalyst 1912's 0/27 port is set to trunk on, it is likely not
communicating with Port 0/21 because port 0/21 hasn't been set to trunk.
Try trunking the 2924XL's port and see what happens. In your configuration,
port 0/27 on the Catalyst 1912 is the one that Spanning Tree will block.
Check its status once you've completed setting up the trunking...
-- Leigh Anne
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of
Pierre-Alex
Sent: February 14, 2001 7:31 AM
To: [EMAIL PROTECTED]; Cisco Groupstudy (E-mail)
Cc: Dale Cunningham
Subject: RE: DISTURBING: Spanning Tree Protocol Does not Work.
Hi Leigh Anne and others:
Leigh Anne, I hope you did not loose sleep over this problem.... At 8:30 PM
after a full day on this problem I went to sleep and crashed ....
So here we again:
You discovered correctly that PORT A is connected to f0/20 and PORT B to f
0/21
ALL those ports are part of VLAN 1 (see output bellow)
And all the ports are in fowarding mode and the lights on the switch are
glowing GREEN! (see below the span tree)
Someone suggested the presence of an etherchannel configured by default. I
will look into this
and will let you know ....
Pierre-Alex
Interface Fa0/20 (port 22) in Spanning tree 1 is FORWARDING
Port path cost 19, Port priority 128
Designated root has priority 32768, address 0050.3ef0.3580
Designated bridge has priority 32768, address 0050.3ef0.3580
Designated port is 22, path cost 0
Timers: message age 0, forward delay 0, hold 0
BPDU: sent 73253, received 5
Interface Fa0/21 (port 23) in Spanning tree 1 is FORWARDING
Port path cost 19, Port priority 128
Designated root has priority 32768, address 0050.3ef0.3580
Designated bridge has priority 32768, address 0050.3ef0.3580
Designated port is 23, path cost 0
Timers: message age 0, forward delay 0, hold 0
BPDU: sent 73251, received 3
--More--
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
___________________________________________
Port FastEthernet 0/26 of VLAN1 is Forwarding
Port path cost 10, Port priority 128
Designated root has priority 32768, address 0050.3EF0.3580
Designated bridge has priority 32768, address 0050.3EF0.3580
Designated port is 22, path cost 0
Timers: message age 20, forward delay 15, hold 1
--More--
Port FastEthernet 0/27 of VLAN1 is Forwarding
Port path cost 10, Port priority 128
Designated root has priority 32768, address 0050.3EF0.3580
Designated bridge has priority 32768, address 0050.50E2.42C0
Designated port is 27, path cost 10
Timers: message age 20, forward delay 15, hold 1
Pierre-Alex
-----Original Message-----
From: Leigh Anne Chisholm [mailto:[EMAIL PROTECTED]]
Sent: Wednesday, February 14, 2001 1:29 AM
To: Pierre-Alex; Cisco Groupstudy (E-mail)
Cc: Dale Cunningham
Subject: RE: DISTURBING: Spanning Tree Protocol Does not Work.
Okay, here's the jist of things.
The Catalyst 2924XL is the root bridge:
> C2924XL#sh span
>
> Spanning tree 1 is executing the IEEE compatible Spanning Tree protocol
> Bridge Identifier has priority 32768, address 0050.3ef0.3580
> Configured hello time 2, max age 20, forward delay 15
> We are the root of the spanning tree
Port 0/26 on the Catalyst 1912 is identifying "Port 22" as the "designated
port":
> Port FastEthernet 0/26 of VLAN1 is Forwarding
> Port path cost 10, Port priority 128
> Designated root has priority 32768, address 0050.3EF0.3580
> Designated bridge has priority 32768, address 0050.3EF0.3580
> Designated port is 22, path cost 0
> Timers: message age 20, forward delay 15, hold 1
Port 22 is, port 0/20 on the Catalyst 2924XL switch:
> Interface Fa0/20 (port 22) in Spanning tree 1 is FORWARDING
> Port path cost 19, Port priority 128
> Designated root has priority 32768, address 0050.3ef0.3580
> Designated bridge has priority 32768, address 0050.3ef0.3580
> Designated port is 22, path cost 0
> Timers: message age 0, forward delay 0, hold 0
> BPDU: sent 46897, received 5
We can deduce that FastEthernet 0/26 on the 1912 switch is directly
connected to FastEthernet 0/20 on the 2924XL switch.
Note that FastEthernet 0/26 on the Catalyst 1912 is identified as the root
port as seen below:
> C1912#sh span
>
> VLAN1 is executing the IEEE compatible Spanning Tree Protocol
> Bridge Identifier has priority 32768, address 0050.50E2.42C0
> Configured hello time 2, max age 20, forward delay 15
> Current root has priority 32768, address 0050.3EF0.3580
> Root port is FastEthernet 0/26, cost of root path is 10
> Topology change flag not set, detected flag not set
> Topology changes 5, last topology change occured 0d02h42m54s ago
> Times: hold 1, topology change 8960
> hello 2, max age 20, forward delay 15
> Timers: hello 2, topology change 35, notification 2
So what we have is a LAN segment connection where one end of the connection
is identified as the root port while the other is identified as the root
port for the non-root-bridge Catalyst 1912 switch. Everything seems to be
"kosher".
All ports on the root bridge are designated ports by default. During the
execution of the Spanning Tree Algorithm, a root port (the port with the
lowest cost path to the root bridge) is identified, and each LAN segment
must identify one port as a designated port. If the LAN segment contains
one or more ports not identified as the root port for the switch or a
designated port, the port is identified as non-designated and is placed in
the blocking state.
If spanning tree was working properly in this topology, and if a looped
topology actually existed, another port on the Catalyst 1912 should show a
port on the Catalyst 2924XL as its designated port with that port on the
Catalyst 1912 as set in the blocking state -- but we don't see that. What
MAY be the case, because on the Catalyst 1912 FastEthernet port 0/27 is set
to trunking but hasn't established a physical connection, is that the port
is operating normally as a member of VLAN 1. If the port in which it is
connected to on the 2924XL is a member of a VLAN other than VLAN 1,
communication shouldn't occur properly -- and a looped topology wouldn't
actually exist. Only port 0/21 on the 2924XL is operating at 100 Mbps in
Full-Duplex mode - so I suspect the 1912 0/27 port IS in fact connected to
the 0/21 port. HOWEVER... if you do a "show interface fastethernet 0/21,
you will see that last input was 3:49:16 - which means it's been quite some
time since this port received anything from what it's connected to... It's
not receiving BPDU's every 2 seconds from 0/27 if it is in fact connected to
0/27...
> C2924XL#sh int f 0/21
> FastEthernet0/21 is up, line protocol is up
> Hardware is Fast Ethernet, address is 0050.3ef0.3597 (bia
0050.3ef0.3597)
> MTU 1500 bytes, BW 100000 Kbit, DLY 100 usec, rely 255/255, load 1/255
> Encapsulation ARPA, loopback not set, keepalive not set
> Full-duplex, 100Mb/s, 100BaseTX/FX
> ARP type: ARPA, ARP Timeout 04:00:00
> Last input 03:49:16, output 00:00:01, output hang never
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
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of
Leigh Anne Chisholm
Sent: February 13, 2001 10:22 PM
To: Cisco@Groupstudy. Com
Subject: RE: DISTURBING: Spanning Tree Protocol Does not Work.
Which ports on the 2924XL are trunking? The only port I can see configured
for trunking is FA0/20. I'm not clear on exactly where you've connected the
1912's 0/26 and 0/27 ports on the 2924XL...
Also, you indicate that you've set up the 2924XL to be the root bridge --
you might want to check what criteria it is that you use when ensuring a
device is deemed to be the root bridge. I suspect you've played with the
wrong parameters to ensure that the 2924XL is the root bridge. Yes, the
2924XL IS the root bridge--but not because of anything you've configured.
-- Leigh Anne
(My apologies if this appears twice in GroupStudy -- I originally sent this
four hours ago, but have yet to see it appear on the list...)
-----Original Message-----
From: Pierre-Alex [mailto:[EMAIL PROTECTED]]
Sent: February 13, 2001 5:22 PM
To: Rik Guyler; Cisco Groupstudy (E-mail)
Cc: Lachisho; [EMAIL PROTECTED]; Dale Cunningham
Subject: RE: DISTURBING: Spanning Tree Protocol Does not Work.
<snip>
C2924XL# sh run
Building configuration...
Current configuration:
!
version 11.2
no service pad
no service udp-small-servers
no service tcp-small-servers
!
hostname C2924XL
!
enable secret 5 $1$OixX$sb.r.W9jrZfT7VfMQdtgF/
!
!
no ip domain-lookup
!
interface VLAN1
ip address 192.168.0.10 255.255.255.0
no ip route-cache
!
interface FastEthernet0/1
switchport access vlan 3
!
interface FastEthernet0/2
!
interface FastEthernet0/3
!
interface FastEthernet0/4
!
interface FastEthernet0/5
!
interface FastEthernet0/6
!
interface FastEthernet0/7
!
interface FastEthernet0/8
switchport access vlan 3
!
interface FastEthernet0/9
switchport access vlan 2
!
interface FastEthernet0/10
!
interface FastEthernet0/11
!
interface FastEthernet0/12
!
interface FastEthernet0/13
!
interface FastEthernet0/14
!
interface FastEthernet0/15
!
interface FastEthernet0/16
switchport access vlan 2
!
interface FastEthernet0/17
!
interface FastEthernet0/18
!
interface FastEthernet0/19
!
interface FastEthernet0/20
switchport mode trunk
!
interface FastEthernet0/21
!
interface FastEthernet0/22
!
interface FastEthernet0/23
!
interface FastEthernet0/24
switchport access vlan 2
!
snmp-server community private RW
snmp-server community public RO
snmp-server chassis-id 0x0E
!
line con 0
exec-timeout 0 0
stopbits 1
line vty 0 4
exec-timeout 0 0
password cisco
logging synchronous
login
line vty 5 14
exec-timeout 0 0
logging synchronous
login
!
end
<snip>
Pierre-Alex
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