Spanning Tree Topology Changes notifications

Hello All,
I've configured RSTP in one of our branch divisions because we decided to add a backup wireless bridge in case one of our fibers gets cut out. Everything is working great , i am getting the desired result, however, i wanted to also syslog the trap msg when a topology change occurs and send it by email. The problem is, i cannot get the root switch to log such an event.
The root switch is a Catalyst 6509, i have tried every level of logging possible, to no avail. I know the trap msg is a notice so i have set my logging to informational, but no change.
I know on c3560's and 3750 i can define to log spanning-tree events, and on my lab setup i do get the trap msgs to my syslog server and email.
What am i missing?! How can i have my Root switch send me that syslog msg?
I do appreciate your help
Thanks in advance!

Hi Sarbjit-2014
Thank you for your response, i dont get any traps msg's at all, doing a sh log on the catalyst will not show me those events.
Below is the output of my sh log ,for obvious reasons i have masked the logging host
Syslog logging: enabled (0 messages dropped, 2 messages rate-limited, 0 flushes,
0 overruns)
Console logging: level debugging, 608 messages logged
Monitor logging: level debugging, 23 messages logged
Buffer logging: level debugging, 608 messages logged
Exception Logging: size (4096 bytes)
Count and timestamp logging messages: disabled
Trap logging: level notifications, 649 message lines logged
Logging to x.x.x.x, 560 message lines logged
I also tried to enter the command spanning-tree logging, but it doesnt seem to be available
Thanks

Similar Messages

What is the command to check the changes in the spanning-tree topology?

What is the command to check the changes in the spanning-tree topology?

Hi,
Few commands which would help are:
1- Show spanning-tree detail
2-show spanning-tree detail | in ieee|from|occur|is exec >> This will give from were the changes occuring- Ex:
C6K1#show spanning-tree detail | in ieee|from|occur|is exec
VLAN0001 is executing the rstp compatible Spanning Tree protocol
Number of topology changes 9536 last change occurred 00:00:29 ago
from GigabitEthernet4/6
3- show spanning-tree active *& show spanning-tree root >> Will give you the root information.
4- show spanning-tree inconsistentports >> If there are any port which are inconsistent state due to STP features.
STP running MST:
===============
show spanning-tree mst configuration >> Need to check and match the same outputs with the other switches running in the same MST domain/region.
show spanning-tree mst detail
show spanning-tree mst <name of the region>
Debug on STP:
============
debug spanning-tree events/bpdu >> would be good but to be run with more cautious.
HTH
Inayath
*Plz rate if this info is usefull.

Spanning-tree Root changes

Hi All,
I presently have a switched VLAN network (one 6500, several 4912G and 2948Gs) with a 2948G access-layer switch as spanning-tree root.I am planning to change the Spanning tree root to the core 6500 switch running PVST+.All switches are running trunking between them.I have read through the basic STP documents and would like to know any precautions to be aware of before doing it.Any first hand experience will be of great help.
Thanx,
Praful

Praful,
Wise decision to change your root switch, I'd just suggest doing it during your slower periods of time, just-in-case.
It really is a quick change, just expect network connectivity to "pause" for up to 50 seconds while spanning tree stablizes.
Provided you have a good handle on how your network is wired, and you're currently running PVST+ across your network, the actual outage should only be 2-3 seconds. I know I've had to tweak our vlans from time to time and I've never seen it take any longer than 2-3 seconds.
HTH
Steve

SF 300 Serires switch not participating in spanning tree?

I just purchased an SF300-24 managed switch and I am running it in layer3 mode. I am testing it out right now and have it connected to two 2950 switches. The SF300 is connected to each 2950 with a four port etherchannel running LACP. When looking at spanning tree all three switches are configured the same when it comes to hello, forward, max age and all three are in RSTP mode. I adjusted the priorities so that the SF300 would be the root but that is not happening.
I only have one VLAN as of right now set up and connectivity between the three switches is fine. The only problem seems to be that the two 2950 switches are the only two switches involved in the determination of the root bridge. Additionally it was the same way before I configured the etherchannel and had the switches connected over single trunk lines.
I would appreciate if someone can expain to me why this is?
Thanks in advance.

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Thanks for your help but know I still cannot get the three devices to talk MST either,it is getting frustrating. If i add a redundant link and directly connect the two 2950's they immediately talk and configure MST. But when I remove that link no info is passed and both 2950's think they are the root even though the SF 300 priority is 0 on all three MST instances. On the SF300 I have the following settings:
Spanning tree: enabled
STP Operation Mode: Multiple STP
BPDU Handling: Flooding
Path Cost: Long
Region name: test
Revision: 1
Max Hops: 20
Max-age: 20
Hello Time: 2
Forward Delay: 15
MST instance 1 Vlan 100
Bridge Priority 0
Designated Root Bridge: Self
Root port: 0
Root path cost: 0
MST instance 2 Vlan 2-5
Bridge Priority 0
Designated Root Bridge: Self
Root port: 0
Root path cost: 0
MST instance 0 all vlans not in instance 1 and 2
Bridge Priority 0
Designated Root Bridge: Self
Root port: 0
Root path cost: 0
For MST interface Settings (both LAGs/instances are thesame)
Int Priority: 128
Path Cost: 20000
Port State: Boundary
Mode: RSTP
Type: Boundary
Designated port ID: 128
Designated Cost: 0
Remain Hops: 20
Forward Transitions: 1
The 2950 switches: (The only difference on the other switch is that the priority is 8192, and the MACs of course)
MST00 is executing the mstp compatible Spanning Treeprotocol
Bridge Identifierhas priority 4096, sysid 0, address 000b.460e.e040
Configured hello time 2, max age 20, forward delay 15
Current root haspriority 0, address 6c50.4dcb.334b
Root port is 65 (Port-channel1), cost of root path is 50000
Topology change flag not set, detected flag not set
Number of topology changes 7 last change occurred 00:18:54 ago
          from Port-channel1
Times: hold 1, topology change 35, notification 2
          hello 2, max age 20, forward delay 15
Timers: hello 0, topology change 0, notification 0
Port 65 (Port-channel1) of MST00 is root forwarding
   Port path cost 50000, Port priority 128, Port Identifier 128.65.
   Designated roothas priority 0, address 6c50.4dcb.334b
   Designatedbridge has priority 0, address 6c50.4dcb.334b
   Designated port id is 128.1000, designated path cost 0
   Timers: message age 4, forward delay 0, hold 0
   Number of transitions to forwarding state: 1
   Link type ispoint-to-point by default, Boundary RSTP
   BPDU: sent 571,received 568
MST01 is executingthe mstp compatible Spanning Tree protocol
Bridge Identifierhas priority 4096, sysid 1, address 000b.460e.e040
Configured hello time 2, max age 20, forward delay 15
We are the root of the spanning tree
Topology change flag not set, detected flag not set
Number of topology changes 9 last change occurred 00:18:55 ago
          from Port-channel1
Times: hold 1, topology change 35, notification 2
          hello 2, max age 20, forward delay 15
Timers: hello 0, topology change 0, notification 0
Port 65 (Port-channel1) of MST01 is boundary forwarding
   Port path cost 50000, Port priority 128, Port Identifier 128.65.
   Designated root has priority 4097, address 000b.460e.e040
   Designated bridge has priority 4097, address 000b.460e.e040
   Designated port id is 128.65, designated path cost 0
   Timers: message age 0, forward delay 0, hold 0
   Number of transitions to forwarding state: 1
   Link type ispoint-to-point by default, Boundary RSTP
   BPDU: sent 598,received 0
MST02 is executingthe mstp compatible Spanning Tree protocol
Bridge Identifierhas priority 4096, sysid 2, address 000b.460e.e040
Configured hello time 2, max age 20, forward delay 15
We are the root of the spanning tree
Topology change flag not set, detected flag not set
Number of topology changes 9 last change occurred 00:19:50 ago
          from Port-channel1
Times: hold 1, topology change 35, notification 2
          hello 2, max age 20, forward delay 15
Timers: hello 0, topology change 0, notification 0
Port 65 (Port-channel1) of MST02 is boundary forwarding
   Port path cost 50000, Port priority 128, Port Identifier 128.65.
   Designated root has priority 4098, address 000b.460e.e040
   Designated bridge has priority 4098, address 000b.460e.e040
   Designated port id is 128.65, designated path cost 0
   Timers: message age 0, forward delay 0, hold 0
   Number of transitions to forwarding state: 1
   Link type ispoint-to-point by default, Boundary RSTP
   BPDU: sent 611,received 0
I notice that on MST01 and 02 they are not receiving BPDU’s,but I am not sure why or if that is the problem. It appears that the SF 300 is not sending BPDU packets for MST01 and 02, but is sending them for MST00. I also attached a capture. I captured the VLAN info for VLAN 100 which is in MST1. on the SF300, it appears that the SF 300 is recieving STP traffic but not generating any.

Spanning Tree Reconfiguration - If Root Port is down.

Hello All,
I have some doubt on STP reconfiguration if Root port is down ...Can any one help...?
As per my understanding, if any port is down due to any reason, the corresponding bridge shall sends a TCN to the root bridge through the root port.
Lets say if a root port is down on a bridge, and so, the topology has to be re-established. As the root port itself is down, how does the Bridge convey the TCN to the root bridge ?
Thanks,
RajaSekhar

Hi Raja, if the root port is down, the TCN notification can't make it to the root bridge since the link is down. The affected device will rely on the last known good bpdu. When the affected device has it's designated port down, it will remove the alternate port from discard once it hits the max age table then progress through the listening, learning, forwarding, at this time the new tcn is sent through the spanning tree topology. Once the TCN reached the root bridge, the root bridge will send a configuration bpdu then the whole spanning tree topology will update.
It can take up to 52 seconds to have the topology update in the entirety depending on spanning tree mode and size of topology.
-Tom
Please rate helpful posts

E100 & E1000 Spanning tree and VLAN reuse

I have a situations where I have two e series cards configured as single card ether-switches in the same chassis. One is an E100 and the other is an E1000. I have spanning tree enabled on all the transport circuit built to these cards. There is no STS connectivity between these cards.
I am reusing a few VLANs between the cards and the cards appear to be sharing spanning tree topology information. Has anyone had similar experiences reusing VLANs and discovered a work around for this? The 15454 documentation is not very descriptive of this situation and lacks detailed STP info as on would expect to be accessible from a Cisco switch.
Thanks,
Ken

I'm not so sure that singlecard/multicard mode has anything to do with STP on E-Series cards. From the book Optical Network Design and Implementation:
"It is important to remember that in the case of the E-Series cards, the Timing and Control 2 (TCC2) common card actually runs the spanning-tree engine with a single instance of STP per node. Each E-Series card plugged into the chassis maintains only a copy of its Layer 2 forwarding table. In the case of ML-Series cards, however, the individual cards maintain copies of the Layer 2 forwarding table and they run an instance of STP." ... "From an STP perspective, however, the entire ONS node is perceived as a single bridge, even though it might contain multiple E-Series cards. For ML-Series cards, however, each card is accounted for as a discrete bridge, and STP uses each and every ML-Series card for its STP computation."

Spanning tree Stability

Folks,
I have recently placed 2 6500 at the core. I am running PVST. I have made one switch as the root primary and the other one is root secondary. My question is what steps can i take to make sure no spanning tree issues arise if some by mistake introduces a switch to the network??? i know i can use the root guard command per interface, but, i was looking for other best practices.
Also, can someone exlain to me how can i switch modify the spanning tree topology if i have already configured a root bridge with a priority of 1?
I will surely rate this post.
Thanks

Well, you can set the priority to 0;-)
Except rootguard you mentioned, there is no real way of preventing someone else to become root because even if you set your root priority to 0, a bridge with a lower mac address could beat you.
STP still assume some kind of cooperation between the switches. If you are in an environment where you absolutely cannot trust the neighbors, you should try avoiding running STP with them. Rootguard is a good safeguard but it will disrupt connectivity when a violation is detected. Plus rootguard will fail to detect problems if the neighbor is hostile and not sending BPDUs at all (bpdufilter).
If you are operating in a kind of service provider model, you could use l2pt instead (waiting for 802.1ad). In that case, you would just run STP with the bridges you control and trust, and let others tunnel their STPs through you (note that in this case, the untrusted devices can create bridging loops through you, but you can rate limit the bandwidth they are wasting to what they pay for).
Regards,
Francois

Mono spanning-tree and PVST

Refering to these two links
http://www.cisco.com/en/US/tech/tk389/tk390/technologies_tech_note09186a0080094665.shtml
http://www.experts-exchange.com/Hardware/Routers/Q_21349385.html
IEEE 802.1Q defines a single instance of spanning tree running on the native VLAN for all the VLANs in the network which is called Mono Spanning Tree (MST). This lacks the flexibility and load balancing capability of PVST available with ISL. However, PVST+ offers the capability to retain multiple Spanning Tree topologies with 802.1Q trunking.
IEEE 802.1Q defines a single instance of spanning tree running on the native VLAN for all the VLANs in the network which is called Mono Spanning Tree (MST). This lacks the flexibility and load balancing capability of PVST available with ISL. However, PVST+ offers the capability to retain multiple Spanning Tree topologies with 802.1Q trunking.
http://networking.ringofsaturn.com/Certifications/BCMSN.php
Per-VLAN Spanning Tree (PVST) ? A Cisco proprietary method of connecting through 802.1Q VLAN trunks, the switches maintain one instance of the spanning tree for each VLAN allowed on the trunk, versus non-Cisco 802.1Q switches which maintain one instance for ALL VLANs. This is the default STP used on ISL trunks.
http://www.informit.com/content/images/1587051427/samplechapter/1587051427content.pdf
The 802.1Q standard defines one unique Spanning Tree instance to be used by all VLANs in the network. STP runs on the Native VLAN so that it can communicate with both 802.1Q and non-802.1Q compatible switches. This single instance of STP is often referred to as 802.1Q Mono Spanning Tree or Common Spanning Tree (CST). A single spanning tree
lacks flexibility in how the links are used in the network topology. Cisco implements a protocol known as Per-VLAN Spanning Tree Plus (PVST+) that is compatible with 802.1Q CST but allows a separate spanning tree to be constructed for each VLAN. There is only one active path for each spanning tree; however, in a Cisco network, the active path can be
I could not get exactly what these Terminology (PVST, instance, PVST+, MST, etc) trying to achieve ?
Any URL and online resource help me to do some extar reading to clarify these terminology

Hi,
The URLs that you have provided all explains the same technical details in different fashion.
I will summarise them here for better clarity.
There are two separate technologies that needs clarity.
1) Method of Trunking many vlans across a link
2) Spanning tree
Now for point 1, we have the IEEE standard 802.1q, which mentions how multiple vlans can be carried across a link. As per this standard a 4 byte tag will be inserted in the ethernet packet, ( inserted between the Destination mac address field and the ethertype field)
This tag will contain the vlan identifier info and some other details ( available in the urls that you have highlighted)
Cisco has a proprietary technology called ISL which effectively does the same job in a different fashion but can only be used in cisco devices.
Now for point 2, again we have IEEE standards like 802.1d ( common/mono spanning tree), 802.1w/RSTP ( Rapid spanning tree) and 802.1s/MSTP.
In 802.1d, there will be only one spanning tree process/instance running for the whole network, irrespective of how many vlans are involved in the network. Hence the whole network is treated as one common domain by the STP protocol.
So, there can be only one root bridge in the network and other bridges will intelligently block the redundant links, we wont have much control to effectively utilise the redundant links.
IEEE 802.1w/RSTP also works in the same fashion, but the convergence time is very fast in this protocol.
Here also there is only one spanning tree instance involved.
In both the above STP protocols, there is only one instance/process of the protocol running in the network, which is common for all vlans. Hence these protocols consume only very less CPU utilisation.
In 802.1s/ MSTP ( multiple spanning tree), extends the 802.1w Rapid Spanning Tree Protocol (RSTP) to have multiple STP instances. In this protocol, we can group the desired vlans in to one Instance of the protocol.
Say for example, lets assume a typical campus network with multiple access switches, 2 distribution/core switches.
Access switches having dual connectivity to the distribution/core switches.
In this topology if we deploy 802.1d or 802.1w, the redundant links from the access switches to the distribution/core switches will be blocked. Only one uplink from the access switch to the distribution layer will be working at any point.
In this network, only one distribution/core switch will be root bridge for the entire network.
But if we deploy 802.1s for this network, we can design it as follows.
We can split the vlans in to two groups,
Group1 => vlan 1 to 50
Group2 => vlan 51 to 100
We can create two instance of MSTP protocol with the following mappings
Instance 1 => for Group 1, with one distribution/core switch as the root bridge
Instance 2 => for Group 2, with another distribution switch as the root bridge
--Continued

Change of spanning-tree root

Hi,
Would appreciate some advise on the following:
The network has already been configured with spanning-tree root primary as well as secondary.
Reassigning another switch to be the spanning-tree root primary/secondary, will it cause a downtime in the network? If yes, how long?
Thanks,
Christina

I'm assuming PVST (not rapid-PVST nor MST, that should behave better)
It is very hard to give an exact estimate of a downtime. First, it's not going to be a global downtime. You can basically compare the topology with your current root bridge and the one with your new root bridge. The ports that need to block in the new topology will block quickly, in a matter of few seconds. However, the ports that were blocked in the old topology and that need to be forwarding in the new topology will take a little bit more than 30 seconds to become forwarding (15 second listening + 15 second learning phases). The topology change mechanism will age out stale CAM entries in 15 seconds. If you add a little margin for BPDU propagation, I would estimate that you are looking at a connectivity loss of about a minute, in part of your network.
The more blocked ports need to move from the old to the new topology, the most connectivity loss you will experience. Some feature like uplinfast are able to switchover quickly between their uplinks in case of root ID changing and will reduce the downtime dramatically. It's mainly the core bridges that will take time to unblock their port.
Note that you can expect better convergence time when a better root is introduced in the network (you are lowering the numerical value of the secondary root priority so that it takes over the primary) than when the primary root is downgraded into secondary (you increase the numerical value of the primary root so that it becomes worse than the secondary).
Regards,
Francois

Prime Infrastructure 2.2 - Network Topology View - Spanning Tree View

Hello Team,
Is it possible on PI 2.2 (latest version) under Maps/Network Topology View to be able to "monitor" the spanning-tree performance?
thanks in advance,
George

Sorry but that's not a currently offered feature.
It would be nice - the Netsys product that Cisco acquired 18-1/2 years ago (and subsequently abandoned) used to do this quite nicely.

Multiple Spanning Tree in a Hub and Spoke topology?

My company is planning to implement Multiple Spanning tree into our hub and spoke topology. Is that possible?
Should I divide up the vlans into instances based on assigned switch or assigned department?
Thank You.

hi, everyone,
i have search a internet draft to describe this situation, "Using an LSA Options Bit to Prevent Looping in BGP/MPLS IP VPNs", from "http://www.ietf.org/internet-drafts/draft-ietf-ospf-2547-dnbit-03.txt"
does anyone can tell me how can disable this function and clear the "DN" bit on a cisco router? thanks very much.

LMS4.1: blocking Topology Spanning Tree View

Hello,
After selecting a VLAN in Topology's Spanning Tree View to want see forwarding and blocked ports, all TopologyView Windows hangs for ever (>15min, reproduceable). The cancel button doesnt work, killing from task manager is the only possibility to stop.
The managed network is a Multiple Spanning tree where a HP device is the root bridge for migration reasons.
Steffen

Sorry but that's not a currently offered feature.
It would be nice - the Netsys product that Cisco acquired 18-1/2 years ago (and subsequently abandoned) used to do this quite nicely.

Changing spanning tree modes / potential outages?

Hi All,
Our core / distribution / access layers are all currently configured to use Cisco's PVST+. We are now a fully populated Cisco network with no standards based STP so we can now migrate to Rapid PVST.
By simply changing the spanning tree mode on a an access switch to Rapid PVST will the vlans with spanning tree enabled suffer an outage ? If so will this be time be based on how the rest of the network is configured ? That is, if the rest of the network is still PVST+ and I change a switch to Rapid PVST will the outage deault to around 45 seconds based on PVST+ timers ?
Furthermore, as I understand it, even though this access switch would now be configured for Rapid PVST, the switch defaults back to PVST until the rest of the network (or VLAN) is configured for Rapid PVST.
My second question is this :
Assuming that all the access layer switches have been migrated to Rapid PVST, what would be the effect of then migrating the distributing and potentially core layer devices to Rapid PVST ? Will they also cause an outage on the VLAN on which STP is enabled ? Again, if so, what would the outage be ? Would this be based on PVST timers or Rapid PVST ?
Thanks in advance.
Chris.

Mike
No problem and please do come back if needed.
One thing I should have answered from your questions but didn't directly was the question of the mac address of the root switch.
The mac address that is important in the root switch election is the one contained in the BPDU not the source mac address of the BPDU. The source mac address is simply that of the port that transmitted the BDPU.
If a switch flushes it's mac address table it would remove that mac address but that would make no difference as to whether the switch believed it had lost it's path to root or not.
In terms of switch to switch communication BPDUs are sent with a multicast destination mac address so removing that mac address has no effect on BPDUs being exchanged.
So the fact that you are seeing the switch reporting it has lost it's path to root is not a direct consequence of the mac address being flushed because it doesn't need that to send and receive BPDUs.
However with all the flooding of end to end devices because of the flushing an indirect consequence may be that BPDUs are getting lost.
Apologies for not making that clearer.
Jon

How Root bridge notifies it Topology change ?

Hi Friends ..
when there is any topology change in non-root bridge , it will generate the TCN bpdu and it will send to all bridges , once root bridge sends the TC bpdu it will flush out the mac table in 15 seconds. What happens when there is a topology change in the root bridge itself ? Will it directly starts the TC bpdu or it will also start the TCN bpdu ?

My personal guess is that there will be a STP recalculation and not simple TCN frame exchange. If a link on a designated port fails, then that port will no longer be in a forwarding state. And given the fact that a root bridge has Designated Ports which are in a forwarding state, then logically an election might take place.

Upstream switch RSTP Topology changes and AP1210 APs

We have AP1210's trunked to 3550/3560 access switches which are inturn trunked to two wireless core 4006 switches.
RSPT is configured on all switches. When a topology change occurs, RPST is very fast in moving the root port (~1 sec) but the designated edge ports (trunk ports) go through the 30 sec 2 x FD STP cycle before going back to forwarding designated ports.
We do not having spanning tree running on the AP1210s, so no bpdus are sent from the AP and we can't use portfast on the access switch to go straight to forwarding.
A colleague felt there was a reason you don't turn on STP on the AP. We have 2 VLANs/Bridges on each AP.
We're looking to speed up spanning tree convergence. Failover testing shows that the 3550 access switch desginated port does not go into forwarding quickly and WL clients lose pings/streaming audio etc during the convergence delay.
Any inputs welcomed.

Hi Sarbjit-2014
Thank you for your response, i dont get any traps msg's at all, doing a sh log on the catalyst will not show me those events.
Below is the output of my sh log ,for obvious reasons i have masked the logging host
Syslog logging: enabled (0 messages dropped, 2 messages rate-limited, 0 flushes,
0 overruns)
Console logging: level debugging, 608 messages logged
Monitor logging: level debugging, 23 messages logged
Buffer logging: level debugging, 608 messages logged
Exception Logging: size (4096 bytes)
Count and timestamp logging messages: disabled
Trap logging: level notifications, 649 message lines logged
Logging to x.x.x.x, 560 message lines logged
I also tried to enter the command spanning-tree logging, but it doesnt seem to be available
Thanks

Spanning Tree Topology Changes notifications

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