Spanning tree and blocked ports

Hello
I have a network built with 5 3560 switches. They are linked together over 6 fiber gigabit links. Two of them are for redundancy. I set up STP and all works fine. STP root is on the same switch for all VLANs.
But I'm wondering why blocked links are only show state blocked on one of the two connected switches. I've read the docu but didn't found a hint.
Thanks for any comment.
Thomas

I guess your question in fact translates to: why is there only one side of my redundant link that is blocking instead of both ends. There are several possible answers to that:
First, because blocking one side is enough;-)
But the an explanation I prefer is to remind that STP cannot know that this link is a fiber going to a single neighbor bridge. This link could be connected to a hub, where on the top of the neighboring bridge there would be some hosts (PCs, routers etc...). To put it short, STP must provide connectivity to this link. That's why *every* link has a designated port that connects it to the root bridge.
Hope this helps;-)
Francois

Similar Messages

Spanning Tree and Admin mac address issues srw2048

Ok, I have a somewhat complex problem and hopefully someone may shed some light or have an idea as to whats wrong.
First the scenario:
I have two Cisco Cat 6509's etherchanneled to each other via two fiber cables. One of these is the STP/RSTP root. I have two SRW2048's.. one trunked to each of these 6509 switches. There is also a trunk between the SRW2048's. All this is to create a redundant topology so that if one of the switches fail's the others can still forward packets to each other. Of course the scenario described is in fact a loop that should be handled by STP/RSTP. I have RSTP enabled on all the switches in the scenario (PV RSTP on the cisco switches as they only do Cisco's brand of per vlan spanning tree). There are 3 vlan's configured on each of the srw2048's (2,55,96). There are corresponding vlan's also on the 6509's. I have put the srw2048's management interface into vlan 2.
The problem:
I need to forward packets between the srw2048's primarily and only use the 6509 that is not the root when a failure happens. I have configured the non-root 6509's spanning tree cost on the etherchannel to be higher then the alternate path through the srw's to the root. I can hook everything up and view the spanning tree and see that the srw2048's interface that goes to the non-root 6509 is blocked, and all other interfaces on the other switches are forwarding. I can in fact ping and get to the admin interface on all the switches. Then for some strange reason the admin interface of the srw2048 plugged into the non-root 6509 stops responding. If I disable either the interface its plugged into on the 6509 or the other srw2048 everything starts working again. Sometimes it responds after many failures for no apparent reason. I looked into the mac-address table on the 6509's and they are conflicting, pointing to each other for the mac-address of the broken srw2048. When I clear the mac-table the admin port comes back for about 5 seconds then again goes dark. When reviewing mac-table on the 6509's they are back to pointing to each other. The odd thing (although I haven't confirmed this completely) is that hosts placed into vlan 2 on that same srw2048 seem to work fine. If there was an STP loop or something misconfigured, I would expect it to effect any host in vlan 2 or the other vlan's for that matter on the srw2048 that stops responding. Alas, I am stuck because I need to manage this switch remotely. My only thought is that for some reason even when the STP status is blocked the broken srw2048 is still sending out arp's of its admin interface and bypassing the STP protocol. I have no way to confirm this, but maybe someone has an idea as to what I'm doing wrong, or otherwise offer a solution. For now, I simply removed vlan 2 from the 6509 that the broken srw2048 is plugged into and everything seems fine.
My apologies for such a long post, but this is somewhat complicated. Thanks in advance for any info.
-Geoff
Message Edited by gmyers on 08-19-2008 10:35 PM

To follow up, I had a ticket open with Linksys about this for about 3 months with no resolution. I submitted packet captures, stp outputs, etc and no luck. I gave up and basically had to revert to a manual failover for redundancy. It's no perfect or fast, but it works every time.
Unless linksys issues a firmware upgrade with this as a fix, I doubt we will be able to ever resolve this on our own.

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

Enable BPDUGuard on Spanning-tree Portfast Trunk Port: Yes or No?

Hello to all the Cisco Experts,
I have been searching around to get a confirmed answer as per my subject, but yet unable to come into any conclusion that could help me.
This is all started when I configured the switchport configuration for my ESXi Server which is a dot1q trunk port. The reference will be as below URL:
http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1006628
The configuration of the switchport will be as below:
interface GigabitEthernet1/0/1
description ESXi
switchport trunk encapsulation dot1q
switchport trunk allowed vlan 11,15
switchport mode trunk
spanning-tree portfast trunk
end
The catch is, I had the bpduguard enabled on the global level in my switch = spanning-tree portfast bpduguard default.
This will enable the bpduguard on the trunk port above due to the switchport is in portfast (the command: spanning-tree portfast trunk).
Some of the guys in this forum mentioned that it is not recommended to have bpduguard on trunk port and some mentioned it is okay to have this.
So, what do you all think on this? Any real life experience dealing with this kind of situtation that can be shared to us over here?
Thank you in advance.

Hi Leo,
First of all, I would never, ever, consider any comment of yours as being offensive so don't worry, none taken. :)
Enabling portfast on a trunk is so "yesterday", in my opinion. If a trunk port(s) or an etherchannel is configured correctly, there's a significant chance portfast is irrelevant. The speed to get the ports to go from down to passing traffic is really boils down to one or two seconds.
Perhaps this is at the core of our different views. To my best knowledge, without the PortFast, a trunk - be it a single port or an EtherChannel - will become forwarding 30 seconds after entering the up/up state, not less. This is valid for STP, RSTP, and MSTP. In addition, if a new VLAN is created or added to the list of enabled VLANs on the trunk, it may take additional 30 seconds for that VLAN to become operational (forwarding) on that trunk. There is nothing besides PortFast and Proposal/Agreement that can cut down this time: the STP must go over the Listening-Learning-Forwarding sequence, and RSTP/MSTP must go through the Discarding-Learning-Forwarding sequence. The "one or two seconds" you have mentioned is perhaps the combined delay incurred by autonegotiation, LACP/PAgP, and DTP, but STP will take its own time and will not be deterred by any of these mechanisms.
I see no benefit but mischief when you enable BPDU Guard on an inter-switch link.
Absolutely agree. That is why it doesn't make any sense to put a BPDU Guard on an inter-switch link, and I have never suggested doing that. The original post, however, deals with enabling PortFast on a trunk link that does not go to another switch but rather connects to an ESXi server on which, obviously, different virtual machines are bridged onto different VLANs.
So what is the reaction of the port if you do happen to enable portfast and BPDU guard on an inter-switch link? Wouldn't the two be a "Jekyll & Hyde", wouldn't it?
It would be just the same as enabling PortFast and BPDU Guard on an access port that happens to be connected to another switch. Upon link-up, the port would become forwarding immediately, and after receiving a BPDU, it would be shot down to err-disabled. The fact the port is an access port or a trunk port makes no difference here. Just as before, I stress that this kind of configuration simply isn't meant to be used on inter-switch links. However, on trunks connected directly to routers, servers, autonomous APs supporting several SSIDs mapped to different VLANs, even to IP phones (remember the mini-trunk config used on old switches on which the switchport voice vlan command only instructed CDP to advertise the voice VLAN but did not cause the port to accept tagged frames in the voice VLAN so it had to be configured as a trunk?) - in all these situations, the PortFast can be beneficial. The BPDU Guard is a natural protective companion to the PortFast - wherever PortFast is eligible to be configured, the BPDU Guard is a natural additional protection to be activated as well.
But given the complexity of interconnection of different switches to various stuff going around, we're happy with leaving portfast on a trunk port disabled.
No argument here - but again, this is about trunks between switches on which I would never suggest using the PortFast or the BPDU Guard. The original post is talking about trunks to end hosts (i.e. edge trunk ports if we extend the terminology a little).
Best regards,
Peter

STP and blocked ports

Hi,
I have five 3550s daisy-chained as a core hosting 2950s where the 2950s' Gig port are attached to different 3550s. Using IOS 12.20. No vlans. I noticed that sometimes a blocked port connecting the 2950 and 3550 is blocked at the 3550 instead of the 2950 (G0/12). Is this normal? Thanks

Follow the path to the root. The root port should not be constantly changing. Check if the root also changes when the root port changes. These blocking ports are known as Designated Port. These switches have a lower cost path to the Root that are called root port.
Take this topology for example:
SwA(root)
g0/1 g0/2
| |
| |
g0/1 g0/1
SwB SwC
g0/2-----g0/2
The drawing above shows SwA being the root and SwB and SwC are connected to one another via g0/2. The SwA being the root will have its gi0/1 and gi0/2 in forwarding mode and are called Designated Port. Both SwB and SwC will have their g0/1 in forwarding mode and are called root port. Now, either SwB or SwC's port gig 0/2 will be DP and the other NDP, this will be based on which one have a lower BID. Let's say the SwB have the lower BID (Bridge Priority + mac-address) than SwC. This means SwB's gig 0/2 will be DP thus will be forwarding and SwC's port gig 0/2 will be NDP and blocking. The only way this will change is if the cost of the path change, the path to the root had changed thus changing the cost and if the BPDU from SwB is not being received on SwC's gig 0/2 which will cause it to transition to DP and forward.

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."

IronPort S160/ASA5510 integration - PAC file and blocking Port 80

We have successfully integrated our ASA5510 and IronPort S160 appliance with Active Directory and eDirectory. We've configured AD to push IE settings to use the IronPort proxy.pac file. Now we need to "Block" un-configured IE access to Port 80 traffic.
In my ASA i have a firewall exception for our WAN IP ranges (source) to any Destination port tcp/http, tcp/https and domain. If I remove the tcp/http from the exception "ALL" port 80 traffic stops, including those PCs configured to use the IronPort Poxy.pac file.
So where have I gone wrong? I want to block un-configured IE access to Port 80, forcing all users to pass through the IronPort appliance.

I hate this job. About 11:10 PM as I was trying to get ready for bed, I had the same thought. Of course I had to test it out, so back to the VPN connection I went and added the filter permit for port 80 for the Ironport's ip address and viola it worked. Thanks for answering my post just the same.

Mac Mail and blocked ports

Hi,
I work in a not-very-Mac-friendly school district, but use a Mac anyway. We've figured out how to open the correct ports, etc. for internet use (via Network Preferences) but still can't access email (on an MS Exchange server) or any POP mail (Yahoo) or .mac mail through the mail program. I'm guessing it's something with a port somewhere that needs to be opened. Any thoughts on what it might be, or how to open ports on Mail?
Thanks for any help anyone might offer.
-Widget

From the client side, you don't need to open any ports in Sys Prefs Sharing at all. Opening ports there is only for dealing with inbound traffic that you didn't initiate and weren't expecting as a response to something, i.e., if you were a mail or web server. But you're not a server, you're a client. So close 'em. Plus, in Mail.app (or any other application for that matter), those port numbers (like 25 or 587 or 465 for smtp, or 110 or 995 for pop, or 143 or 993 for imap) are at the destination mailserver, not your computer.
If you launched Terminal.app, "su {adminUserName}" and "sudo tcpdump -i en1" (en1 if wireless, en0, if ethernet cable) you will find that when you launch Mail and try to check mail or send mail, stuff from your computer is leaving your machine on a randomly chosen (by Mail.app) five-digit port number and it's at the destination server where these port numbers (25, 587, 465, 110, 995, 143, 993) have any meaning. Same holds true for all applications, e.g. Safari, port 80 refers to the web server, not what port on which you are sending out your browser request to the server. The (mail, web, other) server responds back from its port (25, 143, ..., 80, etc.) port to the random port number that your application chose.
Your problem, most likely, is that your IT Dept is blocking outbound traffic destined for any "foreign" host addresses at ports like 25 or 143, that are NOT the host addresses of your IT Dept's own mailservers. They would be blocking this at their firewall to the internet. My work's IT Secret Police does this. So unless they relax their firewall restrictions, you're going to have to do something like use your cellphone as a dialup modem to access those mail accounts, or use webmail (since they probably aren't blocking all http (destination server) port 80 traffic -- although they could be blocking traffic addressed to specific host addresses like yahoo.com/webmail).

SGE2010 switches, VLAN's and a blocked port in spanning-tree

Folks,
I have 2 switch groups.
2 SGE2010's with VLAN's defined as 10,20 and 30
Vlan 10 is the management VLAN, and it uplinks to our border router.
Vlan 20 is the workstation VLAN, and all workstations point to the switch as their default GW
Vlan 30 is the ip phone VLAN, and all phones use this as their gateway.
I would like to put a LAG between said switches, we have some servers on the ip phone switch that need to be accessed by the workstation clients, and the single 100mb link through the router is probably not going to be enough.
As I understand it, because the switches have different networks on them, a simple lag will not work. I did create a lag, and assign ip addresses to each side, however in that mode, it doesn't appear I can block vlan 10 from transiting the LAG, and with out that block I will end up with a logical loop, and spanning-tree will block one of the uplinks, or the LAG itself.
I have attached an image with a diagram of our current set up.
Any help/advice would be much appreciated.

Tom,
I remember our conversation a few weeks ago. I did not get a chance to have a go at MSTP, mainly because I have no expierence with it, and looking at the configuration properities, it looks a little daunting.
It has also been a very busy few weeks with the deployment of 200+ phones across several sites, and the system is functioning great with out the LAG trunk, I am just trying to plan for the future.
I made a few postings a few weeks ago, one here and one on the Cisco forums on reddit, and a user there gave me some advice I have been unable to make work (I think it's just wrong), but I would love to go this route if it is in fact possible.
Here is the thread : http://www.reddit.com/r/Cisco/comments/x91tc/vlan_trunks_spanning_tree_and_a_port_blocked/c5kskch
This user implies it's possible to block a VLAN across the LAG which would end the logical loop problems.
It looks like his advice is to make the LAG into a trunk, and then block specific VLAN's from transiting it, but in trunk mode, I can't assign it an IP, so I am sorta wondering how exactly you transport packets across it.
Can you confirm that his advice is in fact incorrect?
If MSTP is my only route, then I suppose it's time to dig into the docs and see If I cant get it up and running.

Blocked Stack Ports on 2960X-48FPD-L Stack (Unstable Switch Stack!) Spanning Tree?

I am having an issue where 2 2960X-48FPD-L Switches in a redundant flexstack (stack port 1 SW1 to port 2 SW2 and port 2 SW1 to port 1 SW2) ring.
At first running the 15.0(2).EX5 (and earlier EX3, and EX4) version IOS yielded all the ports on the stack master switch refusing to run spanning tree and would only link in amber and not pass any traffic other than CDP information (the slave switch linked in fine).
I upgraded to 15.2(3)E and this solved the problem of the ports not linking in green and participating in spanning tree.
Now, however, about every week or two I lose connectivity to the switch stack and I was able to go to the switch stack locally and found that for some reason the switch stack is blocking and unblocking VLANs on StackPort1 frequently (see below). When I was at the site, I sometimes had connectivity, sometimes not. A stack hard reboot brought everything back up, but this is the second time this has occurred and I would expect the same problem in the next week or so.
Has anyone else run into these issues, and have you found a solution?
I'm guessing that if I either get rid of the redundancy on the switch stack or stack using Ethernet cables between switches the problem will go away, but then what is the point of using stackable switches in a non redundant low speed stack. It seems to me that Spanning tree thinks that I have a spanning tree loop going on with the stack ports which I didn't even think was possible.
What do you think?
Jim
_BAD_TLV: Received SSTP BPDU with bad TLV on StackPort1 VLAN1.
Mar 11 09:02:59: %SPANTREE-2-UNBLOCK_CONSIST_PORT: Unblocking StackPort1 on VLAN0307. Port consistency restored.
Mar 11 09:03:16: %SPANTREE-2-RECV_BAD_TLV: Received SSTP BPDU with bad TLV on StackPort1 VLAN1.
Mar 11 09:03:27: %SPANTREE-2-BLOCK_PVID_PEER: Blocking StackPort1 on VLAN0307. Inconsistent peer vlan.
Mar 11 09:03:42: %SPANTREE-2-UNBLOCK_CONSIST_PORT: Unblocking StackPort1 on VLAN0307. Port consistency restored.
Mar 11 09:03:46: %SPANTREE-2-RECV_BAD_TLV: Received SSTP BPDU with bad TLV on StackPort1 VLAN1.
Mar 11 09:03:47: %SPANTREE-2-BLOCK_PVID_PEER: Blocking StackPort1 on VLAN0307. Inconsistent peer vlan.
Mar 11 09:04:12: %SPANTREE-2-UNBLOCK_CONSIST_PORT: Unblocking StackPort1 on VLAN0307. Port consistency restored.
Mar 11 09:04:22: %SPANTREE-2-RECV_BAD_TLV: Received SSTP BPDU with bad TLV on StackPort1 VLAN1.
Mar 11 09:04:56: %SPANTREE-2-RECV_BAD_TLV: Received SSTP BPDU with bad TLV on StackPort1 VLAN1.
Mar 11 09:05:13: %SPANTREE-2-RECV_PVID_ERR: Received BPDU with inconsistent peer vlan id 207 on StackPort1 VLAN307.
Mar 11 09:05:13: %SPANTREE-2-BLOCK_PVID_LOCAL: Blocking StackPort1 on VLAN0307. Inconsistent local vlan.
Mar 11 09:05:30: %SPANTREE-2-RECV_BAD_TLV: Received SSTP BPDU with bad TLV on StackPort1 VLAN1.
Mar 11 09:06:00: %SPANTREE-2-RECV_BAD_TLV: Received SSTP BPDU with bad TLV on StackPort1 VLAN1.
Mar 11 09:06:04: %SPANTREE-2-UNBLOCK_CONSIST_PORT: Unblocking StackPort1 on VLAN0307. Port consistency restored.
Mar 11 09:06:32: %SPANTREE-2-RECV_BAD_TLV: Received SSTP BPDU with bad TLV on StackPort1 VLAN1.
Mar 11 09:07:02: %SPANTREE-2-RECV_BAD_TLV: Received SSTP BPDU with bad TLV on StackPort1 VLAN1.
Mar 11 09:07:03: %SPANTREE-2-RECV_PVID_ERR: Received BPDU with inconsistent peer vlan id 207 on StackPort1 VLAN307.
Mar 11 09:07:03: %SPANTREE-2-BLOCK_PVID_LOCAL: Blocking StackPort1 on VLAN0307. Inconsistent local vlan.
Mar 11 09:07:34: %SPANTREE-2-RECV_BAD_TLV: Received SSTP BPDU with bad TLV on StackPort1 VLAN1.
Mar 11 09:07:45: %SPANTREE-2-UNBLOCK_CONSIST_PORT: Unblocking StackPort1 on VLAN0307. Port consistency restored.

Jim,
We have also the same problem with our 2960-X switches (access) connecting to a pair of 4500x (VSS) except our issue is with Portchannel with 2 physical links connecting the 2960xs to the 4500.
If we disconnect one of the physical links from the portchannel everything works fine, but when we connect the same physical link back all users lose connectivity and the physical link starts flapping. Here are some of the messages we see in the logs when both physical links are in the portchannel:
Mar 10 18:00:43 EST: %SPANTREE-2-RECV_PVID_ERR: Received BPDU with inconsistent peer vlan id 1 on Port-channel5 VLAN90.
Mar 10 18:00:43 EST: %SPANTREE-2-BLOCK_PVID_PEER: Blocking Port-channel5 on VLAN0001. Inconsistent peer vlan.
Mar 10 18:00:43 EST: %SPANTREE-2-BLOCK_PVID_LOCAL: Blocking Port-channel5 on VLAN0090. Inconsistent local vlan.
Mar 10 18:00:58 EST: %SPANTREE-2-UNBLOCK_CONSIST_PORT: Unblocking Port-channel5 on VLAN0001. Port consistency restored.
Mar 10 18:00:58 EST: %SPANTREE-2-UNBLOCK_CONSIST_PORT: Unblocking Port-channel5 on VLAN0090. Port consistency restored.
Mar 10 18:01:29 EST: %LINEPROTO-5-UPDOWN: Line protocol on Interface TenGigabitEthernet1/0/1, changed state to down
Mar 10 18:01:37 EST: %LINEPROTO-5-UPDOWN: Line protocol on Interface TenGigabitEthernet1/0/1, changed state to up
Mar 10 18:01:48 EST: %LINEPROTO-5-UPDOWN: Line protocol on Interface TenGigabitEthernet1/0/1, changed state to down
Mar 10 18:01:51 EST: %LINEPROTO-5-UPDOWN: Line protocol on Interface TenGigabitEthernet1/0/1, changed state to up
We have upgraded to 15.0(2a).EX5 and still have the same issue.
We have a ticket open with Cisco and have sent them all the logs and debugs and waiting to hear back from IOS developers.
HTH

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.

2960X 15.0(2)EX5 Stack Bug? Master Switch Ports link in Orange, no spanning Tree

Is anyone aware of a bug in version 15.0(2)EX5 for 2960X Switches that would cause a switch in the master role to stop linking in new ports in green (and passing traffic). I have 2 2960X-48FPD-L Switches in a stack and whichever switch I designate master will only link new connections in orange and not pass traffic. All ports linked in show up/up and can be seen in a show cdp neighbor but won't pass any other traffic.
If I unplug the Stacking cables both switches become masters and ports linked in green on the previous member switch stay green, but after it switches to master any new connections plugged in only link in orange.
If I switch priorities and reboot the problem switches to the new master switch and the problem goes away on the member switch.
Also, a switch in the master role does not show any spanning tree instances for ports in the orange link state.
Has anyone seen this issue and do you know of a solution?
Jim

A quick update for those with this same problem.
1. 15.2(3)E turned out to be very unstable causing my switch stack to randomly lockup/reboot one of the switches about once a week.
2. I downgraded back to 15.0(2)EX5 but found a workaround. It turns out the switch stack with the 15.0 versions does not like the switchport voice vlan command on any of the interfaces on the master switch. I simply removed the voice vlan configuration on the interfaces and all the switch ports linked in just fine. I would prefer to run the phones on a voice vlan, but it still works without, just the PC's and phones are on the same vlan.
Jim

How to implement uplink redundancy and spanning tree in SFP-300 switches

We have several Small Business 300 Series Managed Switches, the 10/100 ones with PoE, the first generation ones.
We've been advised to implement uplink redundancy and spanning tree on these switches.
I'm sure spanning tree is a checkbox somewhere in the web interface.
How does one implement uplink redundancy besides interconnecting the switches plus turning on spanning tree (RSTP)??
Thank you, Tom
P.S. I also tried to file a service request but it does not work, I get: "Error 500: Request processing failed; nested exception is java.lang.NullPointerException"

Hello Thomas,
Thanks for using the Cisco Small Business eSupport Community. I've looked through the articles that are available in our Knowledge Base and found a few that I hope will be able to assist you in setting up spanning tree and link redundancy on your SFP300s:
In regards to link redundancy, the following article on LAG can hopefully provide some guidance:
Link Aggregate Group (LAG) Configuration on 200/300 Series Managed Switches
And for your question on setting up STP, here are a few articles with additional information:
Configure Spanning Tree Protocol (STP) Status and Global Settings on 200/300 Series Managed Switches
Setup Spanning Tree Protocol (STP) on a Interface on the 300 Series Managed Switches
I hope that this information helps! Please remember to mark your question as answered and rate if this solves your problem.
Best,
Gunner

Rapid Spanning Tree Question

All,
I have a question about Rapid Spanning Tree reconfiguration. I have to following situation:
As you can see 3 switches with RSTP, and 2 switches without RSTP (or any other spanning tree, just unmanaged).
The 2 switch will form a loop in my network. Switch 1 will block one of the ports and the other port will forward the traffic.
If I break the link "Just Forwarding", my second switch won't be able to cumminucate for around 40 seconds. It will take some time before the backup link will be up again.
Cisco has the Fastforwarding mechanism. Will this help in this situation? I would like to shorten the 40 seconds time.
Thans in advance.

I'd guess the unmanaged devices run legacy spanning tree, and rapid
pvst switches will run rapid according the "heard" protocol. So if it hears
the legacy bpdu, it will run regular spanning tree, hence the 40 second delay.
chris

Dot1q trunk causes block port go to forwarding

Hi
I have three 3560 switches in a fully-meshed scenario, an access switch and 2 distribution switches. when connecting these switches in the triangle topology, since STP running by default one of port go to blocking mode and then loop is prohibited. But when in access switch i set tow ports connected toward distribution switches in trunk mode with command "switch port mode trunk" the Blocked port go to forwarding and i can't understand why?because i think the loop there is yet and spanning tree must block one of ports.
Spanning tree mode is PVST+ and there are 8 VLANs on switches.
The question is how does this situation occur? i couldn't find reason of this situation.
Thanks in advance

Hi,
It would be good that if you can provide the configuration that you had on each switch ports.
Cheers
Zarni

Spanning tree and blocked ports

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