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.
2
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0answers
32 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 ...
3
votes
1answer
62 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 ...
2
votes
1answer
58 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:
...
1
vote
1answer
34 views
Is STP BPDU Guard automatic timeout a good idea with PortFast? [closed]
(I actually have this issue on an HP network but will use Cisco terminology since I think more people are familiar with that)
On edge swtchports intended to face end-user stations we set:
PortFast (...
3
votes
1answer
150 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
51 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
49 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 ...
6
votes
1answer
220 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
53 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
69 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
112 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?
...
0
votes
0answers
29 views
Spanning tree priority values on port-channel
Group Port-channel Protocol Ports
-------------------------------------------------------------------------
1 Po1(U) LACP Gi0/3(P),Gi0/9(P)
4 Po4(U) LACP ...
2
votes
2answers
259 views
Spanning tree Priority values
show spanning-tree interface gigabitethernet 0/2
Switch default
Instance Role State Cost Prio type
-------- ---- ----- ---- ---- ----
MST00 ...
1
vote
2answers
165 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
2k 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
40 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
275 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
51 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
326 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 ...
4
votes
1answer
286 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
173 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
235 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
89 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, ...
2
votes
2answers
78 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. ...
5
votes
4answers
1k views
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.
...
4
votes
2answers
431 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 ...
1
vote
1answer
44 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.
1
vote
1answer
210 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 ...
2
votes
0answers
107 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 ...
3
votes
1answer
515 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 ...
2
votes
1answer
73 views
As a Spanning Tree Protocol Programmer, how will I know when the root bridge ID election is over?
I am trying to implement IEEE 802.1D. I know how the root bridge id is elected.
Initially, every switch will advertise that they are the root bridge.
Next, it will check whether the bridge ID received ...
5
votes
1answer
381 views
Is Per Vlan Spanning Tree or RPVST an open standard or can it only be implemented by Cisco?
I know there are some standards that are CISCO proprietary but have become open standards. CISCO has also updated the RFC to reflect this. So, is this also true for PVST?
Does Juniper or other ...
1
vote
2answers
291 views
spanning tree loop with bpdufilter on acces port but not on trunk?
┌─────┐ ┌─────┐
| A ┼------┼ B |
└─────┘ └┬───┬┘
└---┘ <-- loop
behold the above drawing. this is a test setup connectin switch A and B, and a test loop
A: cisco ...
5
votes
1answer
333 views
How to resolve a spanning tree issue on a server trunk port?
I am having a very strange spanning-tree issue with Cisco Nexus switches.
My server is connected to the TOR switch with trunk configuration because we have multiple VLANs on the server. When I reboot ...
2
votes
2answers
297 views
How should (per-vlan) STP behave when interconnecting access ports from different vlans on the same switch?
Half of the ports of a switch are in vlan 10, the other half in vlan 20, all untagged. In some specific situations, we need someone in the field to be able to interconnect both vlans without access to ...
3
votes
1answer
303 views
Add links to a port channel group without downtime
There are two trunk links with the same configuration connecting two switches. Currently they are independent links and one is blocked with spanning-tree. I would like to convert these to a single ...
2
votes
1answer
75 views
Spanning tree behaviour - topology change
Regarding a next change we have to do, we are studying spanning tree behaviour.
Does the following statement is true ?
In the case of topology change, if a new BPDU is received:
Currently: Root ...
1
vote
1answer
68 views
Replacing a pair of switches and stp
We need replace to a pair of switches with new ones without interrupting traffic.
In order to do that , for some minutes all 4 switches will be interconnected between them - but we need to avoid stp ...
2
votes
1answer
44 views
Edge detection on designated ports
If a switch doesn't receive a BPDU on a particular port it marks this port as "Edge Port". But any designated port won't receive any BPDU even though it was connected to other switches since their ...
2
votes
2answers
213 views
redundant vpn to remote location with redundant links
I have this situation:
Remote location with 6 devices collecting data and each connected to two VPN routers. Bonding is set up for those computers and data is sent to multicast address. Each VPN ...
3
votes
1answer
113 views
Does a bridge have the three STP timers per port or per bridge (one per bridge)?
I was trying to understand Spanning Tree Protocol and I got confused on some points, so I want to ask for some and double check for others:
Do the three timers(including max_age) exist in the bridge ...
2
votes
2answers
101 views
I CAN'T ping PC7
So... I have a set up as below. I ping PC7 from the router. obviously an ARP is sent to determine PC7's MAC address. but it doesnt work. i then decide to set packettracer to simulation mode. i ping ...
2
votes
1answer
133 views
Best way to connect Vlan's / STP / LAG
Am having a problem connecting these concepts together , like when i try thinking of them being ran on the same network. am able to understand each of them separately, But am not able to connect them ...
0
votes
1answer
862 views
What is the EtherType of a BPDU frame sent by a switch which runs Spanning Tree Protocol
I want to know what is the EtherType field of a BPDU frame in various versions and variants of the Spanning Tree Protocol.
2
votes
1answer
1k views
Bridge Assurance with vPC on port type network
I'm running two Nexus 3048 switches as network core and I got an issue when linking another switch (specifically a 2960-X) on the vPC links. Consider the scenario:
+-------+ +-------+
| NX #1 |===|...
4
votes
2answers
500 views
High availability LAN segment with Cisco ISR4451X and 2 x Netgear GS724 - Port-channel vs. BDI vs. BVI?
I have a customer that is getting a new 1Gbps ISP connection and wants his servers connected across two switches for redundancy and protection from:
failure of a router port
failure of a network ...
2
votes
1answer
77 views
Trying to configure STP on a small network and have a few questions
I am trying to configure the switches on a network to use STP or RSTP but I'm confused about how to do this. The network consists of 3 switches, all on the default subnet, so a fairly simple setup. ...
1
vote
2answers
581 views
What could cause network to duplicate packets? STP during convergence?
I have understood that real networks have routing changes, leading to out-of-order delivered IP packets. Real networks also have frequent packet loss.
However, what I have not understood is why could ...
1
vote
1answer
504 views
Cabling two access ports on the same switch from different VLANs
Theoretically would I be able to connect two switch ports together with a simple straight/cross cable on the same switch. If the two ports are in different VLANs (eg. 2 and 22) and ports are in ...
1
vote
1answer
269 views
root port election in STP
I have a question about root-port election in STP.
How to determine root-port on switch 3, both fa0/1 and fa0/2 have port-cost back to root switch (switch 0) of 38, receive BPDU from port fa0/3 of ...
