Discussion for spanning tree

If I want to connect the core switch (SW C3650S) in the corporate network to the core switch in the Data center (C6509E), anything i need to take note of its vtp mode and spanning tree? Will it affect the network in data center for propagation of vlan and spanning tree priority?
vtp mode for corporate core switch is transparent and its spanning tree setting is spanning-tree vlan 1-4000 priority 4096.

From your description, you shouldn't be too concerned. If vtp is transparent, it will ignore and pass along any vtp advertisements that it receives if needed. The stp priority is pretty low. The lowest is 0, and has to be done in increments of 4096. Which switch do you want to keep as the root bridge? If it's the corporate switch, you should be fine as long as the data center doesn't have the same priority or lower.
HTH,
John

Similar Messages

ISE - 802.1X - Loop not detected by spanning-tree

Hello,
I have recently implemented the 802.1X on switchs 3750-X running 15.0(2)SE IOS version.
The spanning-tree bpdufilter and bpduguard are globally enabled on the switchs.
A user has created a loop on the network by connecting its Cisco IP-Phone twice on the network : one wire connected normally from switch to the RJ-45 phone connector and the second wire that should be connected to the PC had also been connected to the switch !
The loop created has not been detected by the switch !
I have made several tests and re-created the problem 3 times on 4 (only one time, the loop has been detected by bpduguard 20 seconds after the port up).
Notice that without 802.1X configured on the same switch port, the loop is quickly detected and ports are err-disabled shutdown.
Switch port with 802.1X is following :
interface GigabitEthernet1/0/9
switchport access vlan 950
switchport mode access
switchport nonegotiate
switchport voice vlan 955
no logging event link-status
authentication control-direction in
authentication event fail action next-method
authentication event server dead action reinitialize vlan 950
authentication event server dead action authorize voice
authentication event server alive action reinitialize
authentication host-mode multi-auth
authentication order dot1x mab
authentication priority dot1x mab
authentication port-control auto
authentication periodic
authentication timer reauthenticate server
mab
dot1x pae authenticator
dot1x timeout tx-period 10
storm-control broadcast level 10.00
storm-control multicast level 10.00
spanning-tree portfast
If I change the host-mode to multi-domain, a MAC violation restriction occurs and shutdown the port. But this is not the config I need.
Is there any reason for spanning-tree not works properly with 802.1X ?
Thanks,
Olivier

Hello Olivier
When using bpdufilter, bpduguard and portfast all at the same time there are many things going on which are not well documented. Now when you add 802.1x to the mix then you really have no documentation. I had to do many labs on my own to finally have my configuration, and also discovered some bugs. According to my experience you shouldn't use bpdufilter and you should use bpduguard on the switchport not in the global config.
Please read the following links about the differences between global and port bpdufilter, differences between global and port bpduguard, configuring bpduguard along with portfast , configuring bpdufilter along with portfast, and configuring bpduguard along with bpdufilter.
http://aitaseller.wordpress.com/2010/01/17/bpdu-filter-vs-bpdu-guard-what-is-the-difference/
http://costiser.wordpress.com/2011/05/23/subtle-difference-for-portfast-bpdufilter-used-together-globally-or-at-interface-level/
https://learningnetwork.cisco.com/thread/21103
http://blog.ipexpert.com/2010/12/06/bpdu-filter-and-bpdu-guard/
Please rate if this helps

No Spanning-Tree Vlan # on C2950

Hello everyone,
I've recently found that one of the switches on my network (which I never set up) is running a "no spanning-tree vlan 3, 5, 10" command, which I want to remove, but I have been unable to. When I do try and type in "spanning-tree vlan 3" nothing comes up, but when I show spanning tree it lets me know that it doesn't exist.
Is there a command I'm missing? (It's a larger number of vlans)
Thanks in advance,
David

I'm not sure there would be anything for spanning tree to calculate if no ports on the switch are assigned to vlan 3. Try assigning an unused port to vlan 3 and see if your output of sh spanning-tree vlan 3 changes.

Nexus spanning tree pseudo configuration

Hi
I am trying to understand the pseudo configuration commands in a Nexus hybrid topology.
I have vlans a, b and c only in the vPC side of the topology. I have peer switch configured and the same stp priority on both switches.
In the standard Spaning-tree topology I have completely seperate vlans x, y and z.
What should I be configuring in the pseudo config section ? Do I define a pseudo root priority for all vlans a, b, c and x, y, z or just for the standard spanning tree vlans x, y and z. I need to avoid and, even short, spanning tree outages if I take one Nexus out of service for a short time.
My thinking is that if one Nexus is out of service the physical mac will be used and potentially reduce the root priority of the vPC vlans causing a TCN and STP recalculation in vlans a, b and c. This can be avoided by configuring a pseudo root priority for all Vlans lower than the current spanning tree priority shared by the vPC peers. Is this correct ? However, since I have a shared priority of 8192 on current vPC vlans will configuring, for example, a pseudo root priority of 4096 on those vPC vlans won't this also cause the TCN and recalculation I am trying to avoid ? Is the benefit of the pseudo root config only obtained if it is configured at the start when the vPC is formed and prior to the peer switch command being issued ?
Thanks, Stuart.

Hi Ajay,
It is recommended that switch-to-switch links are configured with the spanning-tree port type normalcommand. The one exception is the vPC peer-link which is recommended to configure with the spanning-tree port type network command.
Take a read of the Best Practices for Spanning Tree Protocol Interoperability from page 56 of the vPC Best Practice Design Guide for further information on this.
Regards

Redundant connection, spanning tree protocoll

Between two buildings i want to establish a redundant network connection. If one of the connections fails, the other connection shall transport the network data automatically. There is a SRW2024 in every building. They are connected by a fibre-cable between the miniGBIC ports 24 of every switch. This combination exists two times.
In one building (Keller in the appended pdf-file) there is a rack with MPEG4 codecs. This rack has a built in unmanaged switch with two ports. This ports are patched to one port of the SRW2024.
In the other building (Pforte) there is a PC which receives the MPEG4 streams. It is connected to a fifth SRW2024 which receives the streams of the two connections on ports 1 and 2.
In my first try i have enabled the spanning tree protocoll in all 5 switches. The PC received the MPPEG4 streams. But when i disconnect one of the fibre connections the system comes to an unstable condition where the MPEG4 streams are interrupted sometimes and no network connection is possible.
Even if i reconnect the fibre, the system switches the streams off and on and was not stable.
Where is my fault, is it enough to configure only the fifth switch for spanning tree ?
It would be glad if anyone has an idea to solve the problem.
Michael

Hi Michael,
I have no experience with the series, but I see in the documentation that you can stack the switches. If you stack they, I think they will work as one logical one like a 3750 e.g. and you can use a Port-channel configuration.
If I`m wrong, we should take a close look to the STP config, to make sure which one will be the root and which ports are up to make the situations "controlled"
regards,
Sebastian

View spanning tree configuraton for all the switches in ciscoworks

Hi All,
Is there any way I can see spanning tree configuration for all the switches we have on our networks in Ciscoworks.
Waiting for your kind reply.
Thanks in advance
samir

This can be done from within Campus Manager's Topology Services. Open up the LAN Edge View map, and you should seesome switch clouds on the map. If you drill into one of the clouds, you should see a Spanning Tree option in the right-hand tree. If you expand this, you can visualize the spanning tree for MISTP or even for each VLAN.

Spanning tree for VLANS

Hi,
I need an answer to this puzzling scenerio i have been asked to work with.I have two vlans with about 10 switches on each end and there is a link switch that has a connection to both sides of the VLAN. I have been asked to create a singular spanning tree for the entire scenerio. how can i go about this.
please i am awaiting the opinions of anyone knowledgable in this line. thanks.

Hi, I agree you can config MST on your router to reduce the number of spanning tree instances runing on the switch from one per vlan. You will have to map your vlan range to the MST, useful CLI commands are
spanning-tree mode mst
spanning-tree mst configuration
name (name)
revision( revision number)
instance (number) vlan (vlan range)
check your config using
show spanning-tree mst configuration.
Hope thsi will hlep you get started.
DW

Challenge: Spanning Tree Control Between 2 links from Switch DELL M6220 to 2 links towards 2 switches CISCO 3750 connected with an stack (behavior like one switch for redundancy)

Hello,
I have an Spanning tree problem when i conect 2 links from Switch DELL M6220 (there are blades to virtual machines too) to 2 links towards 2 switches CISCO 3750 connected with an stack (behavior like one switch for redundancy, with one IP of management)
In dell virtual machine is Spanning tree rapid stp, and in 3750 is Spanning tree mode pvst, cisco says that this is not important, only is longer time to create the tree.
I dont know but do you like this solutions i want to try on sunday?:
Could Spanning tree needs to work to send one native vlan to negociate the bdpus? switchport trunk native vlan 250
Is it better to put spanning-tree guard root in both 3750 in the ports to mitigate DELL to be root in Spanning Tree?
Is it better to put spanning- tree port-priority in the ports of Swicht Dell?
¿could you help me to control the root? ¿Do you think its better another solution? thanks!
CONFIG WITH PROBLEM
======================
3750: (the 2 ports are of 2 switches 3750s conected with a stack cable, in a show run you can see this)
interface GigabitEthernet2/0/28
description VIRTUAL SNMP2
switchport trunk encapsulation dot1q
switchport trunk allowed vlan 4,13,88,250
switchport mode trunk
switchport nonegotiate
logging event trunk-status
shutdown
interface GigabitEthernet1/0/43
description VIRTUAL SNMP1
switchport trunk encapsulation dot1q
switchport trunk allowed vlan 4,13,88,250
switchport mode trunk
switchport nonegotiate
shutdown
DELL M6220: (its only one swith)
interface Gi3/0/19
switchport mode trunk
switchport trunk allowed vlan 4,13,88,250
exit
interface Gi4/0/19
switchport mode trunk
switchport trunk allowed vlan 4,13,88,250
exit

F.Y.I for catylyst heroes - here is the equivalent config for SG-300 - Vlan1 is required on the allowed list on the catylyst side (3xxx/4xxx/6xxx)
In this example:
VLANS - Voice on 188, data on 57, management on 56.
conf t
hostname XXX-VOICE-SWXX
no passwords complexity enable
username xxxx priv 15 password XXXXX
enable password xxxxxx
ip ssh server
ip telnet server
crypto key generate rsa
macro auto disabled
voice vlan state auto-enabled !(otherwise one switch controls your voice vlan….)
vlan 56,57,188
voice vlan id 188
int vlan 56
ip address 10.230.56.12 255.255.255.0
int vlan1
no ip add dhcp
ip default-gateway 10.230.56.1
interface range GE1 - 2
switchport mode trunk
channel-group 1 mode auto
int range fa1 - 24
switchport mode trunk
switchport trunk allowed vlan add 188
switchport trunk native vlan 57
qos advanced
qos advanced ports-trusted
exit
int Po1
switchport trunk allowed vlan add 56,57,188
switchport trunk native vlan 1
do sh interfaces switchport po1
!CATYLYST SIDE
!Must Explicitly allow VLan1, this is not normal for catalysts - or spanning tree will not work ! Even though it’s the native vlan on both sides.
interface Port-channel1
switchport trunk encapsulation dot1q
switchport trunk allowed vlan 1,56,57,189
switchport mode trunk

Spanning tree query for extending existing lan

Hi Guys,
I've got a network setup where I need to add a new set of switches have some new vlans that are independant to the existing environment but i have some of the existing vlans propogate accross.
My current setup is:
and my new design is this:
The 5505-02 is there so that i can easily manage acl's so that only some users can access the new vlans such as 200. And in the future put in idfw to manage this via AD groups.
My concern is regarding spanning tree. The current set up the 3750-01 , 2960-01, sf300-01 and sf300-02 are all set to default pvst where the 3750-01 is the root bridge for all existing vlans
With having the vlan 101 and 102 being propagated across to the new environment what is the best way of tackling STP for this? could I manually set the root primary and the priority to be lowest for these two vlans as the 3750-01? And then the same for the new 200 and 201 as the new 3750-02?
Or would setting a different mode be best i.e mst?
thanks
Rich

Rich
Are you proposing to use the same IP subnet for vlans 101 and 102 on the new switches ?
If so unless the ASA 5505-02 is in transparent mode then you will not be able to extend vlans 101 and 102 across to the new switches ie. if it is in routed mode that is a L3 hop and you generally can't extend a L2 vlan across a L3 hop. There are technologies that allow you to do this but i dont think any of them are supported on the 3750 switches.
If you are making the ASA 5505-02 transparent then it would need to be transparent for a trunk link and i don;t know whether this is possible. You may want to ask in the firewalling forums.
So before worrying about STP can you clarify what you are going to be doing with ASA 5505-02 and that whether or not you are proposing to use the same IP subnet for those vlans on the new switches ?
One last question. Any particular reason why you are using a square topology as opposed to simply using multiple uplinks from each 2960 to the 3750 stack ?
Jon

Sg-300 - 3750 stack with SPANNING-TREE root problem.

Morning. I think ive configured a few hundred switches, maybe a thousand in my time, but never have a faced such horribleness that is the SG-300. After this week, I think ill refuse to touch them.
Got 2 voice vlans and running a few vrf's on a 3750 stack. but this discussion is about layer 2.
2 x 3750 stacked
1 x voice switch sg-300 company A voice vlan 18 - Po1 up to 3750 distributed etherchannel Po1 (LACP active both sides) 2 ports in channel
1 x voice switch sg-300 company B voice vlan 19 - Po1 up to 3750 distributed etherchannel Po2 (LACP active both sides) 2 ports in channel
Allowed vlans on both sides (command on Port-channel) are data A, Voice A, Mgt A to switch A
Allowed vlans on both sides (command on Port-channel) are data B, Voice B, Mgt B to switch B
It seems that these switches are limited to one voice vlan....
and that spanning tree BPDU's are ignored (or not recevied- havnt released the shark yet). let me explain.
originally when using "smart port" the switch with the lowest mac address, whatever Voice vlan was configured would take over the other switche's voice vlan, argh what a nightmare.
I gave up on the GUI as its far to complcated and have Almost got this working.
I am now using auto voice vlan, but have disabled smart macro. I hope that disabling smart macro stop other switches from learning the switch with the lowest mac address's voice vlan. So far so good - in the LAB. No where was it documented in the cli guide how do disable this stupid feature.
DHCP is working from scope on core, can mange the switches etc etc, access vlan voice vlan all good (after a monster battle).
Now I have an issue with spanning tree.
spanning tree priority for vlans 1-4094 on the 3750 is 4096.
spanning tree priority for vlans 1-4094 on the SG-300's is 6xxxx.
ALL switches think that they are the root. (well the "logical" 3 of them) The 3750's for all vlans, and the SG-300 for the one instance as it doesnt support per vlan. (I am not interested in trying MST here..this is not a datacentre)
On the 3750's Ive tried ieee, pvst, rpvst, while matching the non per-vlan equivalent on the SG series.
What is the difference between a General port and Trunk Port on a SG-300 specific to spanning tree, native vlans (when you can just configure an untagged vlan anyway!!) and what is the relevance to the way the bpdu's are carried?
And why the need for a PVID, when you can tell a port what is tagged and what isnt.
Does the trunk need Vlan1 to be explicitly allowed, and untagged? Does the Po trunk need to be a general port with PVID configured? in vlan 1?
I need to sort this, as cannot put an access switch into production that thinks it is the root of the tree. I wish I had a 2960.... a 3500XL..anything
Does anyone have CLI commands that can help here?

F.Y.I for catylyst heroes - here is the equivalent config for SG-300 - Vlan1 is required on the allowed list on the catylyst side (3xxx/4xxx/6xxx)
In this example:
VLANS - Voice on 188, data on 57, management on 56.
conf t
hostname XXX-VOICE-SWXX
no passwords complexity enable
username xxxx priv 15 password XXXXX
enable password xxxxxx
ip ssh server
ip telnet server
crypto key generate rsa
macro auto disabled
voice vlan state auto-enabled !(otherwise one switch controls your voice vlan….)
vlan 56,57,188
voice vlan id 188
int vlan 56
ip address 10.230.56.12 255.255.255.0
int vlan1
no ip add dhcp
ip default-gateway 10.230.56.1
interface range GE1 - 2
switchport mode trunk
channel-group 1 mode auto
int range fa1 - 24
switchport mode trunk
switchport trunk allowed vlan add 188
switchport trunk native vlan 57
qos advanced
qos advanced ports-trusted
exit
int Po1
switchport trunk allowed vlan add 56,57,188
switchport trunk native vlan 1
do sh interfaces switchport po1
!CATYLYST SIDE
!Must Explicitly allow VLan1, this is not normal for catalysts - or spanning tree will not work ! Even though it’s the native vlan on both sides.
interface Port-channel1
switchport trunk encapsulation dot1q
switchport trunk allowed vlan 1,56,57,189
switchport mode trunk

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.

"Peer-switch" command on vPC domain and spanning-tree priority interaction

Hi guy,
We have 2 N7K (N7KA and N7KB) which will be running vPC in hybird and pure vPC environment.
I have a question about the Hybird and pure vPC environment. With the "peer-switch" command enable, should i tune the spanning-tree priority to be the same for all the vlan running on vPC on both N7KA and N7KB? This way, when i enter the "sh spanning-tree vlan X(vPC vlan) detail" command on N7K, it will list both N7K announc itself as "We are the root of the spanning tree".Also the switch running spanning-tree with N7K vPC vlan (Hybird), will see both N7K has the same priority (4096), and it is not desirable for a spanning-tree environment. Therefore, i used the "spanning-tree pseudo-information" on N7KB to tune the spanning-tree priority to "8192" and the switch running spanning-tree with N7K will list N7KB has a priority of 8192(perfect).
However, I notice some strange "show" output on the switch running Port-channel with the N7KA and N7KB. The "Designated bridge" priority is flapping as show on the switch. It is constantly changing between "4096 and 8192" with the same vPC system wide mac address.
Entering the "sh spanning-tree vlan X detail" command repeatly on switch with port-channel toward N7KA and N7KB.
>>sh spanning-tree vlan 10 detail
Port 65 (Port-channel1) of VLAN10 is root forwarding
Port path cost 3, Port priority 128, Port Identifier 128.65.
Designated root has priority 4106, address 0013.05ee.bac8
Designated bridge has priority 4106, address 0013.05ee.bac8
Designated port id is 144.2999, designated path cost 0
Timers: message age 15, forward delay 0, hold 0
Number of transitions to forwarding state: 1
Link type is point-to-point by default
BPDU: sent 5, received 603
one sec later.
>>sh spanning-tree vlan 10 detail
Port 65 (Port-channel1) of VLAN10 is root forwarding Port path cost 3, Port priority 128, Port Identifier 128.65. Designated root has priority 4106, address 0013.05ee.bac8 Designated bridge has priority 8202, address 0013.05ee.bac8 Designated port id is 144.2999, designated path cost 0 Timers: message age 15, forward delay 0, hold 0 Number of transitions to forwarding state: 1 Link type is point-to-point by default BPDU: sent 5, received 603
Configuration:
N7KA
spanning-tree vlan 1-10 priority 4096
vpc domain 200
peer-switch
N7KB
spanning-tree vlan 1-10 priority 4096spanning-tree pseudo-information vlan 1-10 designated priority 8192
vpc domain 200
peer-switch

We have a issue similar to this in our environment. I am trying to upgrade the existing 3750 stack router with 2 Nexus 5596 running VPC between them. For the transition I have planned to create a channel between 3750 stack and 5596's. Once this environment is set, my plan is to migrate all the access switches to N5k.
The issue is when I connect the 3750 port channel to both N5Ks, all the Vlans on 3750 started to flap. If I connect the port channel to only one N5K everything is normal; but when I connect the port channel to both N5K running VPC, vlans are flapping. Any idea what is going wrong here? Am I missing something?

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.

Dlsw spanning-tree

Hi, my name is fabio and i´ve a problem with dlsw.
When i´ve configured de dlsw in a router 3600 the router 7206 that has the conection with mainframe, the same lost the comunication e appears the messagem in 3600 router, look at below:
Note: A random Spanning Tree Bridge Identifier address of 0000.0cfe.6628
has been chosen for Bridge Group 50 since there is no mac address
associated with the selected interface.
I´am putting the scheme in .ppt.
Can i sending configurations of 3600 and 7200 to help you.
thanks

Fabio
I'm not sure what the issue is here. The mac-address of the end-stations will not be visible in the 4948 as the SNA traffic is encaps'd in ip. Can you supply sh vers, sh runn, sh dlsw pe, sh dls reach, sh dls circuit, sh bri from the 3640 and the 7206. What is the mac-address of the end-station to which mac-address is it trying to connect ?
Matthew

2950 spanning tree issue

Here is the problem we are having , we have a 2950 hooked to a 6509 hybrid dist box with approx 90 vlans on it . We hook up a new 2950 and we get the following message, Dec 21 19:47:45.116: %SPANTREE_VLAN_SW-2-MAX_INSTANCE: Platform limit of 64 STP instances exceeded. No instance created. Ok , I know about the spanning tree issues with the 2950 only having limited PVST instances . But up at the dist side we have "manually pruned off all but 5 vlans on the trunk feeding this 2950 with the "clear trunk" command . I thought manually pruning off the vlans from the trunk would eliminate this problem , maybe i have a misunderstanding of how this works. Also the message on the 2950 complains about it only having 64 instances of spanning tree yet when you do a "show vtp status it says it supports 250 instances locally so whats up with that , 2950 running 12.1.22EA4 . So I guess I'm asking is there any way around this for the 2950 . Also in client/server mode do you have to manually prune off the vlans on both the server side and the client side ??

Hello Glen,
I guess instead of manually pruning the VLANs off the trunk, you could also try and enable VTP pruning globally on the 6509 (set vtp pruning enable). I assume you have the 6509 configured as the VTP server (set vtp mode server) ?
I am not sure if CatOS and IOS defaults to the same VTP version, can you check this (with 'show vtp domain' for CatOS and 'show vtp status' for the IOS switch) ?
Also, in a purely IOS environment, manually pruning VLANs off a trunk requires doing that only on the server side, but with a mix of CatOS and IOS, it might have to be done on both sides, you might want to give it a try and use the 'switchport trunk allowed' command on the 2950 as well...
Regards,
GP

Discussion for spanning tree

Similar Messages

Maybe you are looking for