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hel27n
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Spanning-Tree Root

Thu Apr 19, 2012 7:21 am

Hello,

I am trying to confirm which of my cisco switch is the spanning-tree root. I know which I prefer to hold the spanning-tree and I ran the command spanning-tree vlan 1 root on this switch

I would now like to check that this command has worked and so I ran the command 'show spanning-tree root active' and received the detail below.
Can you please help me make sense of this and determine which port the mac address references (From this I take it that 00b0.d0f5.cf31 is the root, how can I determine which port this is).

Any help with this would be much appreciated.


VLAN0001 is executing the ieee compatible Spanning Tree protocol
Bridge Identifier has priority 32768, sysid 1, address 0021.1ce5.bd80
Configured hello time 2, max age 20, forward delay 15
Current root has priority 32768, address 00b0.d0f5.cf31
Root port is 1 (GigabitEthernet0/1), cost of root path is 23
Topology change flag not set, detected flag not set
Number of topology changes 37959 last change occurred 00:28:20 ago
from GigabitEthernet0/2
Times: hold 1, topology change 35, notification 2
hello 2, max age 20, forward delay 15
Timers: hello 0, topology change 0, notification 0, aging 300

Port 1 (GigabitEthernet0/1) of VLAN0001 is forwarding
Port path cost 19, Port priority 128, Port Identifier 128.1.
Designated root has priority 32768, address 00b0.d0f5.cf31
Designated bridge has priority 32769, address 000f.23a9.a100
Designated port id is 128.1, designated path cost 4
Timers: message age 3, forward delay 0, hold 0
Number of transitions to forwarding state: 1
Link type is point-to-point by default
BPDU: sent 24, received 2590

Port 2 (GigabitEthernet0/2) of VLAN0001 is forwarding
Port path cost 100, Port priority 128, Port Identifier 128.2.
Designated root has priority 32768, address 00b0.d0f5.cf31
Designated bridge has priority 32769, address 0021.1ce5.bd80
Designated port id is 128.2, designated path cost 23
Timers: message age 0, forward delay 0, hold 0
Number of transitions to forwarding state: 1
Link type is point-to-point by default
BPDU: sent 882, received 0

Port 3 (GigabitEthernet0/3) of VLAN0001 is forwarding
Port path cost 100, Port priority 128, Port Identifier 128.3.
Designated root has priority 32768, address 00b0.d0f5.cf31
Designated bridge has priority 32769, address 0021.1ce5.bd80
Designated port id is 128.3, designated path cost 23
Timers: message age 0, forward delay 0, hold 0
Number of transitions to forwarding state: 1
Link type is point-to-point by default
BPDU: sent 983, received 0

Port 4 (GigabitEthernet0/4) of VLAN0001 is forwarding
Port path cost 100, Port priority 128, Port Identifier 128.4.
Designated root has priority 32768, address 00b0.d0f5.cf31
Designated bridge has priority 32769, address 0021.1ce5.bd80
Designated port id is 128.4, designated path cost 23
Timers: message age 0, forward delay 0, hold 0
Number of transitions to forwarding state: 1
Link type is point-to-point by default
BPDU: sent 2375, received 0

Port 5 (GigabitEthernet0/5) of VLAN0001 is forwarding
Port path cost 100, Port priority 128, Port Identifier 128.5.
Designated root has priority 32768, address 00b0.d0f5.cf31
Designated bridge has priority 32769, address 0021.1ce5.bd80
Designated port id is 128.5, designated path cost 23
Timers: message age 0, forward delay 0, hold 0
Number of transitions to forwarding state: 1
Link type is point-to-point by default
BPDU: sent 1453, received 0

Port 6 (GigabitEthernet0/6) of VLAN0001 is forwarding
Port path cost 4, Port priority 128, Port Identifier 128.6.
Designated root has priority 32768, address 00b0.d0f5.cf31
Designated bridge has priority 32769, address 0021.1ce5.bd80
Designated port id is 128.6, designated path cost 23
Timers: message age 0, forward delay 0, hold 0
Number of transitions to forwarding state: 1
Link type is point-to-point by default
BPDU: sent 7132, received 0

Port 7 (GigabitEthernet0/7) of VLAN0001 is forwarding
Port path cost 100, Port priority 128, Port Identifier 128.7.
Designated root has priority 32768, address 00b0.d0f5.cf31
Designated bridge has priority 32769, address 0021.1ce5.bd80
Designated port id is 128.7, designated path cost 23
Timers: message age 0, forward delay 0, hold 0
Number of transitions to forwarding state: 1
Link type is point-to-point by default
BPDU: sent 1010, received 0

Port 8 (GigabitEthernet0/8) of VLAN0001 is forwarding
Port path cost 100, Port priority 128, Port Identifier 128.8.
Designated root has priority 32768, address 00b0.d0f5.cf31
Designated bridge has priority 32769, address 0021.1ce5.bd80
Designated port id is 128.8, designated path cost 23
Timers: message age 0, forward delay 0, hold 0
Number of transitions to forwarding state: 1
Link type is point-to-point by default
BPDU: sent 4326, received 0

Port 9 (GigabitEthernet0/9) of VLAN0001 is forwarding
Port path cost 4, Port priority 128, Port Identifier 128.9.
Designated root has priority 32768, address 00b0.d0f5.cf31
Designated bridge has priority 32769, address 0021.1ce5.bd80
Designated port id is 128.9, designated path cost 23
Timers: message age 0, forward delay 0, hold 0
Number of transitions to forwarding state: 1
Link type is point-to-point by default
BPDU: sent 3420, received 0

Port 10 (GigabitEthernet0/10) of VLAN0001 is forwarding
Port path cost 19, Port priority 128, Port Identifier 128.10.
Designated root has priority 32768, address 00b0.d0f5.cf31
Designated bridge has priority 32769, address 0021.1ce5.bd80
Designated port id is 128.10, designated path cost 23
Timers: message age 0, forward delay 0, hold 0
Number of transitions to forwarding state: 1
Link type is point-to-point by default
BPDU: sent 4013, received 0

Port 11 (GigabitEthernet0/11) of VLAN0001 is forwarding
Port path cost 100, Port priority 128, Port Identifier 128.11.
Designated root has priority 32768, address 00b0.d0f5.cf31
Designated bridge has priority 32769, address 0021.1ce5.bd80
Designated port id is 128.11, designated path cost 23
Timers: message age 0, forward delay 0, hold 0
Number of transitions to forwarding state: 1
Link type is point-to-point by default
BPDU: sent 1018, received 0

Port 12 (GigabitEthernet0/12) of VLAN0001 is forwarding
Port path cost 4, Port priority 128, Port Identifier 128.12.
Designated root has priority 32768, address 00b0.d0f5.cf31
Designated bridge has priority 32769, address 0021.1ce5.bd80
Designated port id is 128.12, designated path cost 23
Timers: message age 0, forward delay 0, hold 0
Number of transitions to forwarding state: 1
Link type is point-to-point by default
BPDU: sent 2894, received 0

Port 13 (GigabitEthernet0/13) of VLAN0001 is forwarding
Port path cost 4, Port priority 128, Port Identifier 128.13.
Designated root has priority 32768, address 00b0.d0f5.cf31
Designated bridge has priority 32769, address 0021.1ce5.bd80
Designated port id is 128.13, designated path cost 23
Timers: message age 0, forward delay 0, hold 0
Number of transitions to forwarding state: 1
Link type is point-to-point by default
BPDU: sent 138949, received 0

Port 15 (GigabitEthernet0/15) of VLAN0001 is forwarding
Port path cost 100, Port priority 128, Port Identifier 128.15.
Designated root has priority 32768, address 00b0.d0f5.cf31
Designated bridge has priority 32769, address 0021.1ce5.bd80
Designated port id is 128.15, designated path cost 23
Timers: message age 0, forward delay 0, hold 0
Number of transitions to forwarding state: 1
Link type is point-to-point by default
BPDU: sent 990, received 0

Port 16 (GigabitEthernet0/16) of VLAN0001 is forwarding
Port path cost 100, Port priority 128, Port Identifier 128.16.
Designated root has priority 32768, address 00b0.d0f5.cf31
Designated bridge has priority 32769, address 0021.1ce5.bd80
Designated port id is 128.16, designated path cost 23
Timers: message age 0, forward delay 0, hold 0
Number of transitions to forwarding state: 1
Link type is point-to-point by default
BPDU: sent 939, received 0

Port 17 (GigabitEthernet0/17) of VLAN0001 is forwarding
Port path cost 100, Port priority 128, Port Identifier 128.17.
Designated root has priority 32768, address 00b0.d0f5.cf31
Designated bridge has priority 32769, address 0021.1ce5.bd80
Designated port id is 128.17, designated path cost 23
Timers: message age 0, forward delay 0, hold 0
Number of transitions to forwarding state: 1
Link type is point-to-point by default
BPDU: sent 1009, received 0

Port 19 (GigabitEthernet0/19) of VLAN0001 is forwarding
Port path cost 19, Port priority 128, Port Identifier 128.19.
Designated root has priority 32768, address 00b0.d0f5.cf31
Designated bridge has priority 32769, address 0021.1ce5.bd80
Designated port id is 128.19, designated path cost 23
Timers: message age 0, forward delay 0, hold 0
Number of transitions to forwarding state: 1
Link type is point-to-point by default
BPDU: sent 138688, received 0

Port 20 (GigabitEthernet0/20) of VLAN0001 is forwarding
Port path cost 19, Port priority 128, Port Identifier 128.20.
Designated root has priority 32768, address 00b0.d0f5.cf31
Designated bridge has priority 32769, address 0021.1ce5.bd80
Designated port id is 128.20, designated path cost 23
Timers: message age 0, forward delay 0, hold 0
Number of transitions to forwarding state: 1
Link type is point-to-point by default
BPDU: sent 9076, received 0

Port 22 (GigabitEthernet0/22) of VLAN0001 is forwarding
Port path cost 4, Port priority 128, Port Identifier 128.22.
Designated root has priority 32768, address 00b0.d0f5.cf31
Designated bridge has priority 32769, address 0021.1ce5.bd80
Designated port id is 128.22, designated path cost 23
Timers: message age 0, forward delay 0, hold 0
Number of transitions to forwarding state: 1
Link type is point-to-point by default
BPDU: sent 138966, received 0

Port 23 (GigabitEthernet0/23) of VLAN0001 is forwarding
Port path cost 4, Port priority 128, Port Identifier 128.23.
Designated root has priority 32768, address 00b0.d0f5.cf31
Designated bridge has priority 32769, address 0021.1ce5.bd80
Designated port id is 128.23, designated path cost 23
Timers: message age 0, forward delay 0, hold 0
Number of transitions to forwarding state: 1
Link type is point-to-point by default
BPDU: sent 138966, received 0

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Re: Spanning-Tree Root

Thu Apr 19, 2012 8:15 am

hel27n wrote: Current root has priority 32768, address 00b0.d0f5.cf31
Root port is 1 (GigabitEthernet0/1), cost of root path is 23



So your root bridge is found out of port Gi0/1, and has a mac of 00b0.d0f5.cf31. This should certainly help you find it (now connect to the device on Gi0/1, and repeat the 'show spanning-tree root' until you get to the root)
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hel27n
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Re: Spanning-Tree Root

Thu Apr 19, 2012 9:11 am

Port 1 on this switch is connected to a 3com switch

Port 19 is connected to a Cisco ASA firewall which in turn connects to a Cisco Router.
I was informed that I should set my Cisco 2960 as the spanning tree for the network as it has the firewall connected to it.

Can you please advise on how I can further check who holds the spanning tree and how I can change it to be the 2960. I am not a cisco expert and so am not clear on the results which are being presented to me.

Thanks

stuart475898
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Re: Spanning-Tree Root

Thu Apr 19, 2012 1:00 pm

You say you issued the command spanning-tree vlan 1 root? The command should be spanning-tree vlan 1 root primary
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Re: Spanning-Tree Root

Thu Apr 19, 2012 1:14 pm

stuart475898 wrote:You say you issued the command spanning-tree vlan 1 root? The command should be spanning-tree vlan 1 root primary


...and I wouldn't do this during production hours.
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Re: Spanning-Tree Root

Fri Apr 20, 2012 4:45 am

Hello,

While in the 'CISCO Network Assistant' tool I entered Device Manager and tried running the command from there, result said successful (see attached) however when I run show spanning tree I still get the same mac address.

I tried to run the command via telnet but am having difficultly in accessing the configure prompt. Can you advise on this?
Attachments
configure.JPG
configure.JPG (17.59 KiB) Viewed 800 times

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Re: Spanning-Tree Root

Fri Apr 20, 2012 10:11 am

just remember the
spanning-tree vlan 1 root primary
is kinda asking for trouble as it's beatable
you need a priority of 0 to be sure you at least tie for the root possition
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Re: Spanning-Tree Root

Fri Apr 20, 2012 10:13 am

I would also do
sh span lan 1
much easier to find the path to the root IMO
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Re: Spanning-Tree Root

Fri Apr 20, 2012 10:22 am

sh span root is also handy

hel27n
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Re: Spanning-Tree Root

Mon Apr 23, 2012 10:00 am

mellowd wrote:sh span root is also handy

I ran all these and they still show the root as being port 1 (which is connected to a 3com switch)

My firewall is connected to port 19 and I want this to be the root. How can I change this

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Re: Spanning-Tree Root

Mon Apr 23, 2012 10:40 am

firewalls don't run spanning-tree.
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Re: Spanning-Tree Root

Mon Apr 23, 2012 2:12 pm

ristau5741 wrote:firewalls don't run spanning-tree.


ooops, I was wrong there, they do.
the ASA 5505s don't.

I really need to get back on target with the FIREWALL study.
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Re: Spanning-Tree Root

Mon Apr 23, 2012 2:29 pm

Have you ran the command spanning-tree vlan 1 root primary or spanning-tree vlan 1 priority 0? If so, were there any errors on the CLI?
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Re: Spanning-Tree Root

Thu Apr 26, 2012 10:19 am

ristau5741 wrote:
ristau5741 wrote:firewalls don't run spanning-tree.


ooops, I was wrong there, they do.
the ASA 5505s don't.

I really need to get back on target with the FIREWALL study.
mellowd wrote:sh span root is also handy



I have an ASA 5510, does it have a spanning-tree?

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Re: Spanning-Tree Root

Thu Apr 26, 2012 10:23 am

As far as I know, no Cisco ASA does spanning tree, as they aren't switches.
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Re: Spanning-Tree Root

Thu Apr 26, 2012 12:45 pm

Dinger wrote:As far as I know, no Cisco ASA does spanning tree, as they aren't switches.


see prev message


I think i created an infinite loop
2 messages up.
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