Questions tagged [spanning-tree]
For questions about Spanning Tree Protocol (STP), a common protocol to prevent bridge loops at OSI layer-2.
274
questions
0
votes
3answers
42 views
Using MSTP with RSTP
I have two layer-3 switches connected with two redundant links that I'm trying to run PTP OSPF sessions across, a la:
(OSPF)
VLAN 1002
- - - - - - - - - - - -
/ ...
1
vote
2answers
37 views
How would a bridge loop occur?
As I understand it, STP is used to prevent bridge (/switch) loops, which will typically occur in the case of redundant links on a switch.
But how can a loop occur and cause a broadcast storm?
If a ...
1
vote
2answers
42 views
RSTP - minimum hello time?
1) What's the minimum possible "hello time" for Rapid Spanning Tree (RSTP)? Is it possible to reduce the hello time to e.g. 0.1 seconds?
2) Is the minimum dictated by the RSTP standard, or would it ...
0
votes
2answers
77 views
Do I need STP enabled on all switches in a loop?
I have a network architecture where each of my N switches is connected to two others, making it a perfect loop. For example see the diagram below:
I know that in order to avoid broadcast storms, I ...
1
vote
1answer
57 views
RSTP Sync received every 2 minutes after a TC
While digging into logs (debug spanning-tree event has been enabled) in order to troubleshoot communication losses after topology changes.
I was able to notice once I triggered a TC, one specific ...
0
votes
1answer
36 views
Why doesn't STP apply only to broadcast/unknown unicast frames?
All known unicast/multicast frames shouldn't cause loops since they have a known destination.
So they can use all the available bandwidth.
What am I missing?
0
votes
1answer
36 views
What is the impact of VTP pruning against RSTP topology?
While working on a network using VTP (without pruning yet), I noticed the STP topology (for VLAN 10 let say as an example) was including all switches even the ones not having any interface in the VLAN ...
0
votes
1answer
27 views
End to End propagation delay computation for STP
While reading a bunch of details about STP timers on this Cisco website
https://www.cisco.com/c/en/us/support/docs/lan-switching/spanning-tree-protocol/19120-122.html#f1
I could not understand how ...
0
votes
1answer
33 views
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 ...
1
vote
1answer
45 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 ...
1
vote
1answer
36 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 ...
0
votes
1answer
90 views
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
1
vote
1answer
105 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 ...
1
vote
1answer
76 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 ...
1
vote
1answer
123 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 ...
0
votes
1answer
63 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
...
0
votes
1answer
51 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?
1
vote
2answers
156 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 ...
3
votes
1answer
161 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 ...
0
votes
1answer
47 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 ?
0
votes
2answers
38 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 ...
2
votes
2answers
78 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 ...
0
votes
2answers
83 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
4
votes
0answers
256 views
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 ...
5
votes
2answers
348 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-...
0
votes
0answers
43 views
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.
...
1
vote
1answer
536 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 ...
4
votes
1answer
350 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 ...
3
votes
1answer
205 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?...
3
votes
1answer
285 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 ...
4
votes
1answer
513 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 ...
3
votes
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:
...
4
votes
1answer
237 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 ...
1
vote
2answers
469 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 ...
1
vote
2answers
65 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 ...
7
votes
1answer
1k views
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 ...
0
votes
3answers
138 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 ...
0
votes
1answer
403 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 ". ...
1
vote
1answer
351 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?
...
2
votes
2answers
528 views
Spanning tree Priority values
show spanning-tree interface gigabitethernet 0/2
Switch default
Instance Role State Cost Prio type
-------- ---- ----- ---- ---- ----
MST00 ...
2
votes
2answers
886 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 ...
9
votes
3answers
3k views
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 ...
1
vote
2answers
65 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 !!
4
votes
2answers
559 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 ...
3
votes
1answer
181 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 ...
4
votes
2answers
695 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 ...
5
votes
1answer
464 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. ...
1
vote
1answer
313 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 ...
2
votes
2answers
624 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 ...
3
votes
3answers
144 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, ...
