Questions tagged [spanning-tree]

For questions about Spanning Tree Protocol (STP), originally defined by IEEE 802.1D, to prevent bridge loops at OSI layer-2.

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Redundant links [closed]

I have configured 3 switches with redundant links, with IP addresses :S1 192.168.1.1, S2 192.168.1.2, S3 192.168.1.3 all of them on vlan 1. Now they can't communicate what could be the problem
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Why does HPE disable STP by default? [closed]

It this certainly true that switches needs STP to avoid loops or broadcasts storms, but recently I saw the configuration of my Hewlett Packard switch and I noticed that it has STP feature disabled by ...
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41 views

Is there a problem with “max age” definition in STP?

In "CCNP and CCIE Enterprise Core ENCOR 350-401 Official Cert Guide" we have this definition of max age: Max age: This is the maximum length of time that passes before a bridge port saves its BPDU ...
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35 views

Endianness of data fields inside BPDU

I'm working on a frame/packet decoder and am seeing inconsistent data regarding the endianness of the MaxAge/Hello/ForwardDelay fields inside a spanning-tree BPDU. Below is a picture of a wireshark ...
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I have L2 network in Delhi, can it communicate without router to L2 network in Florida, using only STP protocol,

using only STP protocol, no NVE etc should be used, is it feasible
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103 views

Why Do We Use STP (Spanning Tree Protocol) or RSTP (Rapid Spanning Tree Protocol) When Packets are Not Routed Optimally?

I am new to networking so this probably a naive question. I've been reading up on the spanning tree protocol and understand why it's necessary in a network (it prevents loops) and I understand that ...
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1answer
68 views

STP Convergence: How does a port initially in blocking state know it needs to change to a designated port?

I am attempting to gain a better understanding of how STP converges when certain state changes occur that affect the STP topology. In this scenario (see below) Switch A (SwA) is the root switch with ...
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1answer
107 views

Why do Designated Ports in STP still send BPDUs if the otherside of the link is blocking?

Is there a particular reason for a Designated Port to continue sending out BPDUs after convergence has occurred on a link where the other side is in a STP blocking state? I get the idea of a ...
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54 views

STP Shut Down Port for Camera on HP Procurve

I have a VLAN dedicated for camera devices. We have learned that some camera ports keep going into the down state, and the logging indicates it is caused by STP: sw404(config)# show logging -r 7 ...
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45 views

STP Priority field and 4 bits in multiples of 4096

For the STP Priority Field, how do you get "multiples of 4096" out of 4 bits?
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139 views

Nexus 6001 How to find source of STM_LEARNING_OVERLOAD

Several time ago I've foud that NX-OS sends STM_LEARNING_OVERLOAD EET: %FWM-4-STM_LEARNING_OVERLOAD: system experiencing unusual number of new address notifications - deferring learn notification for ...
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1answer
135 views

802.1Q Tagged BPDU?

Question for didactic purposes where I try to keep it IEEE bound and put Cisco off the discussion unless strictly necessary. I refer to 802.1D-1998 and the question is to understand, after clarifying ...
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46 views

DHCP server access problem

what will stop a pc from receiving ip address from DHCP server? Is it STP , VTP , 802.1Q or DTP ? What is the most preferable ?
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31 views

STP Loop with Third Party Switches

STP Loop with Third Party Switches I manage a network mostly comprised of older Avaya ERS 3500 series switches. Recently another department has bought a package that comes with it's own server rack, 2 ...
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73 views

What constitues an STP fail on this setup?

We have a host which has a bonded Ethernet interface. only one is active, at each time, when the other fails, the MAC address moves to the other interface and traffic continues... But at the SP ...
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82 views

Is Spanning Tree Protocol Needed?

If there are two switches connected directly together with two links is spanning tree protocol needed? please see below snippet
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Cisco nexus STP loopguard

I have cisco nexus switches in vPC and they are connected to HP c7000 blade center switches and all my c7000 blade server has Linux Bridge is running, i believe something went wrong somewhere in Linux ...
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298 views

Should portfast be configured on the physical interfaces or on the logical port-channel, or both?

I'm using a Cisco 3750 switch and have two physical ports configured in a port channel that connects to a router. Should I configure spanning-tree portfast on the physical interfaces or on the port-...
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What spanning tree IEEE protocol does the Cisco 1252AG Aironet access point support?

Link to data sheet We're running Cisco IOS version 15.2(2)JA1. What version of the IEEE STP is supported on the Cisco Aironet 1252AG access points? We are using the "bridge X protocol ieee" command. ...
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422 views

Why STP has to be disable on Trunk Ports?

I have 5 Switches on a Private Network 10.0.0.0/8 with 8 Vlans. On Access ports is running Rapid STP. On Trunk Ports between Switches should i disable STP or not? I would be very pleased if someone ...
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311 views

Best Practice for Voice and Data VLAN on single port

We have multiple interfaces currently configured with the below on our Cisco 3750x switch. interface GigabitEthernet1/0/21 switchport access vlan 4 switchport trunk encapsulation dot1q switchport ...
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1answer
192 views

STP packets and QoS

Routing protocol packets are IP packets and therfore they could have different DSCP values to have different priorities (which is implemented by QoS policy) during congestion. How about non-IP packets?...
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248 views

What does “l2protocol peer x” exactly do?

i'm struggeling with some Layer2 Service within one of my customer's MPLS networks. My aim is to provide a L2VPN Service between two ISR4000 Boxes that act as CPE in my MPLS platform. This L2 Service ...
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450 views

Finding the root cause of Spanning-Tree recalculations (on Cisco Nexus 9000s)

I have a nagging Rapid PVST problem on some Nexus 9000 switches. Rapid-PVST keeps recalculating 3 to 5 times an hour. We have in this topology (summarized): Edge Router ...
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1answer
1k views

spanning-tree port type edge trunk on port-channel vs physical interface

If i configure spanning-tree port type edge trunk on physical interface instead of port-channel does that work? Or i have to do spanning-tree port type edge trunk on port-channel ? Example: ...
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226 views

Strange flooding during installing new switch in network

This is very strange issue i am noticing. In our datacenter we have every switch in rack has cisco vPC configured in short whole datacenter running vPC so there is no loop for spanning-tree anywhere ...
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408 views

RSTP recovery time with Ethernet ring

I am trying to test Rapid Spanning Tree on an Ethernet ring. Most of what I found does not seem to apply to my specific situation, but I am happy to be pointed elsewhere. Specifically, I have one ...
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57 views

Spanning tree protocol

I have a questions regarding STP and i would like to know if STP is only a feature of layer 2 switches? i am on GNS3 and i am trying to enable STP but it tells me that there is no spanning tree ...
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MSTP and Rapid-PVST+

We have a medium sized network running all Juniper except for one building. This building is shared with another group, and is completely Cisco. We just trunk our VLANs up there. Our Juniper network ...
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3answers
126 views

Using VRRP instead of XSTP

Suppose there is a ring with two routers (L3 switch) and 3 switches. All devices are configured properly.VRRP is configured on both routers and one virtual gateway is introduced to switches and their ...
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351 views

designated ports and root ports in STP

I am just a bit confused about designated ports in STP, i know how to determine them and the confusion is about the say " designated port is the only port in charge to forward traffic on a segment ". ...
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331 views

Disable STP and force port state on a Avaya 4950 switch port

I know how to connect a switch on a router Avaya VSP 7200 by disabling STP with the command : no spanning-tree mstp force-port-state enable but how to force port state on a switch Avaya 4950? ...
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501 views

Spanning tree Priority values

show spanning-tree interface gigabitethernet 0/2 Switch default Instance Role State Cost Prio type -------- ---- ----- ---- ---- ---- MST00 ...
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757 views

Fastest spanning tree in multiple-ring topology

I have a topology in which there is a main ring and some nodes in the main ring have a minor ring. 1- which STP configuration has the fastest convergence time? How would you configure spanning tree ...
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I have a single ethernet switch. Should I use spanning tree?

I have a single ethernet switch. Should I use spanning tree? If there is a redundant link, definitely need to enable STP. In a single switch, how is it possible to have a redundant link? Any other ...
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64 views

Spanning tree - per vlan spanningntree vs rapid spanning tree

Which spanning tree protocol is link state and which one is vector state. We have stp and rapid spanning tree !!
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478 views

Network Redundancy with LACP Trunking

I would like to set up a redundant link between two switches. I have four ports available to accomplish this. Scenario A: Switch 1 has ports 1+2 trunked together via LACP. They are plugged into ...
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158 views

Cascading a switch interface to another switch

We have a service provider switch which has an interface that we use to connect to other users over. We have been advised by the SP that we can use this interface how we wish (i.e. feed it into a ...
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656 views

spanning tree RootGuard question on vPC switches

I have following diagram and two distribution switch connected back to back over vPC Related spanning-tree question is it ok to use RootGuard on both distribution switch where access switch is ...
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435 views

How does STP convergence work?

Consider the IEEE 802.1D (first revision) Spanning Tree Protocol. I have read a lot of articles and forum entries about STP convergence. Often I do find contradictions about the convergence mechanics. ...
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1answer
296 views

PVST + MST + RSTP network. Possible to make it work?

I have got a network (around 100 switches) which looks like this: Cisco 2960 - can do PVST, RSTP, MST MRV mr2228-s2c - can do STA, MSTP HP 1810 - can do RSTP, STP Two main Ciscos are linked with ...
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562 views

OpenvSwitch Spanning-tree priority for specific Vlan ID

I'm new to the SDN technology, I have 12 year's experience working with Cisco products, On Cisco devices, a user can set different STP priority Per VLAN ID Like : Switch(config)#spanning-tree VLAN ...
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3answers
136 views

Are the Switches not direct connect to the root-bridge need select root port in the STP circuit?

In the STP circuit like bellow, will the Router2 select a root port? or just the Router1 and Router3 select root port? in a tutorial it says "all the non-root bridge node will select a root-port, ...
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1k views

Does Switch need its own MAC address?

I saw a post say Switch do not need its MAC address, unless it's an administrable Switch for managing. but I found the spanning-tree protocol need a MAC address of Switch to form STP Root Bridge ID. ...
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Do layer 3 protocols use layer 2 protocols?

I saw the STP on layer 2. The guy that made the tutorial says at the end : Even though it seems that Layer 2 access layer solutions are slowly being replaced by blazing fast Layer 3 solutions. ...
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2answers
577 views

Spanning Tree on the interface that resides at end users

I do not understand why we use portfast and in fact STP on the interface of a switch that is directly connected to end users. Indeed, a user can interfere with the STP election and perform DDoS (that ...
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51 views

Does STP create a minimum spanning tree?

From the algorithm described in P&D textbook it looks to be minimum (if all edge weights are 1). Can't find mentions on Wikipedia or a quick google search.
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633 views

Spanning-tree MSTR port role

What is the MSTR port role in Spanning-tree ? It shows up on boundary ports between MST regions and switches running (R)PVST+. Note that it shows up only on the switches running MST. It seems to ...
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170 views

How to set portfast default on Dell FTOS Switches?

I'm configuring a Dell S3148 switch running FTOS 9.14.0.1 and I would like to achieve similar functionality of the following Cisco IOS commands: spanning-tree portfast default spanning-tree portfast ...
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2k views

How to solve a BKN* Port Issue on a cisco catalyst

There is a Cisco ISR 4451 connected with Portchannel to a Catalyst 3850 Stack and there are some VLANs enabled, but only one does not come up for a Portinconsistence. I figure out an Issue on the ...

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