Skip to main content
New
Stack Overflow Jobs powered by Indeed: A job site that puts thousands of tech jobs at your fingertips (U.S. only). Search jobs

Questions tagged [spanning-tree]

For questions about Spanning Tree Protocol (STP), a common protocol to prevent bridge loops at OSI layer-2.

Filter by
Sorted by
Tagged with
0 votes
0 answers
45 views

Dell VLT (MLAG) and Root Bridge Priority

I'm not a network guy... We'll be deploying some Dell switches configured for VLT soon. From what I understand, this is just Dell's version of MLAG. Correct me if I'm wrong, but I'm pretty sure that I ...
DOSed_And_Confused's user avatar
2 votes
2 answers
76 views

STP related question

Hi this is a portion of my current set up.. All vlan ports are untagged. Everything works and communicates fine until a connection is made between the 2 switches it takes down the network and the pc ...
Blake's user avatar
  • 23
1 vote
0 answers
46 views

Need for additional Master Port Role in MSTP

MSTP IEEE specification, it says the Root Port for CIST will be the Master Port for all MSTIs. I'm wondering what is the need for this additional port role, is it just to isolate the region boundaries ...
esdeath's user avatar
  • 11
1 vote
1 answer
56 views

Will implementing a MSTP stack allow me to use that interchangeably between STP and RSTP

I've to provide support for STP/RSTP/MSTP, while going through the specification I see the Force Protocol Version majorly ensures compatibility between STP/RSTP bridges. Mostly, I see the transmission ...
esdeath's user avatar
  • 11
0 votes
0 answers
13 views

Fast port connection and ability to daisy chain unmanaged switches on Cisco Catalyst [duplicate]

I have a Cisco Catalyst 2960-S that I use in a home environment. In the configuration I currently have (very basic, basically just switchport mode trunk on upstream and switchport mode access on reset ...
drcomputer's user avatar
0 votes
1 answer
66 views

In STP, how does a switch know that a peer port is blocked?

Let's consider the below image: Let's assume the following: Cat1 is the root bridge fa0/23 on cat2 is blocked after stp has converged When a frame arrives at cat1 to be forwarded to cat2, how ...
host_unreachable's user avatar
1 vote
2 answers
114 views

Spanning Tree Protocol - Redundant Links

There are two things about STP that confuse me. Consider the following network: There is a designated port from S1 to S3. There is also one from S1 to S2, and then S2 to S3. If S1 sends an unknown ...
Jossie Calderon's user avatar
0 votes
2 answers
82 views

RSTP convergence of p2p links

Ramping up on RSTP here. One thing that is unclear to me is how RSTP links converge initially on P2P links. Consider the classic 3 switch topo as below: For RSTP, won't all the links move to ...
host_unreachable's user avatar
2 votes
2 answers
257 views

Juniper EX bpdu-timeout-action not blocking interface

In short I'm trying to configure bpdu-timeout-action block on trunk interfaces to other switches, but it doesn't go into blocking mode when there are no BPDU's received (eg, when connecting my laptop ...
Hugo's user avatar
  • 23
1 vote
2 answers
336 views

What Does Exactly Happen When A Switch Is Connected To A Portfast Port?

I am trying to get a thorough understanding of what does happen when a switch is connected to a portfast port on another switch that is part of a stable STP network in case of: 1- the port has no ...
Shadi's user avatar
  • 285
0 votes
1 answer
394 views

How does STP technically generate the path cost for an interface?

How path cost is being calculated in STP is still not clear to me. Let's say we got this architecture, where all switches were just turned on for the first time: During BPDUs exchange, every switch ...
Floji's user avatar
  • 319
0 votes
1 answer
67 views

how can a STP switch time out MAC addresses from the table in Listening state?

I am looking over some materials describing STP's port states (the original version from 802.1d) and they say that a port in Listening state can not modify the MAC address table (it doesn't learn new ...
Marcus's user avatar
  • 183
5 votes
2 answers
1k views

Two switches, double connection, no LACP: how does it work?

We have a network with an HP 1910-24 and a V1410-16 (unmanaged). The two are connected via two network cables, but there's no Link Aggregation configured on the 1910, and all the connections are ...
Maxxer's user avatar
  • 153
3 votes
1 answer
91 views

Spanning-Tree vlan priority on a pass through switch

I am still understanding a bit about this priority for spanning-tree on VLANs. I have a SWITCH A that is the root of a VLAN. It trunks through SWITCH B with no ports on that vlan. SWITCH B trunks to ...
JukEboX's user avatar
  • 461
3 votes
2 answers
335 views

Loops in an STP-enabled network - How?

I've got a question about STP/RSTP (it applies to both, but I'll just say STP). If I connect several switches and the STP algorithm eventually creates a loop-free environment, then how can a single ...
Attila M's user avatar
2 votes
2 answers
161 views

MST - multiple instance design in single region

I am preparing for migration of this rather simple network layout from RST to MST: From what I have read so far, it looks like the best approach is to avoid interoperability issues and simply rollout ...
quantum's user avatar
  • 177
1 vote
1 answer
79 views

Is non-blocking per-VLAN (rapid) spanning tree configuration possible?

Imagine a pair of switches connected with a couple of trunk links created in the following fashion: Assuming the numbers on lines correspond to different VLANs, how would you arrange a working ...
quantum's user avatar
  • 177
1 vote
1 answer
33 views

Do STP 802.1D support Uplink Fast, Backbone Fast and Port Fast?

Do STP 802.1D support Uplink Fast, Backbone Fast and Port Fast ? Aren't these features cisco proprietary ? Is IEEE later add these feature into 802.1D ? If so, Why are they not called Alternate Port, ...
jacky chong's user avatar
1 vote
0 answers
105 views

HSRP does not work on two switches. Cisco

The problem is this: clients receive IP addresses from the L31 DHCP server, but they cannot ping the gateway, although HSRP seems to be working, there are no problems, I suspect that this is a bug in ...
Syslog's user avatar
  • 11
1 vote
0 answers
113 views

Cisco device chooses link with higher cost as the root

The problem is that psw11 (SG350-28P) is choosing the path to sw10 (C2960L-48TS-LL) with a cost of 20000 as the root instead of the path to sw56 (C2960L-48TS-LL) with a cost of 10000, even though the ...
CherMet's user avatar
  • 11
0 votes
1 answer
571 views

Palo Alto 440 and FS 5860 Switches -- L2 Loop/Spanning-Tree issue

I have identified what seems to be a looping issue, due to STP not blocking an alternate path. As you can see in the diagram, ports Eth7 and Eth8 on the switches connect to the Active/Passive PA-440 ...
James's user avatar
  • 1
1 vote
2 answers
70 views

Alternative Solution to Avoid Loop aside STP

SITUATION: I have two switches SW1 and SW2. These two switches are connected with two trunk ports. While SW1 is connected to PC1, SW2 is connected to PC2.  If PC1 sends a broadcast frame to PC2 via ...
Adekunle's user avatar
0 votes
1 answer
58 views

How would a switch know that it should forward a frame through a different interface in a STP topology?

Imagine the following STP topology If PC0 was to ping PC1, all of the switches would create entries in their MAC table according to the source MAC address of the PCs associated with the corresponding ...
Mitrixsen's user avatar
  • 803
0 votes
1 answer
79 views

Is it risky to change hardcoded STP mLAG port cost on Cisco Nexus LACP port

When two Cisco Nexus are connected in VPC, the stp cost is hardcoded to 200 for the mLAG LACP ports. I would like to manually change the cost on my devices because my 2G and 200G links have the same ...
setenforce 1's user avatar
2 votes
2 answers
534 views

Spanning tree loop prevention

Can I get some advice on what STP features to enable as best practice please, mainly to mitigate loops? In the past a user mistakenly connected two floor ports together causing a loop. Below are the ...
gs78's user avatar
  • 21
1 vote
3 answers
626 views

Why switch uses Mac address during implementation of spanning tree protocol (STP)?

We know that layer2 switch doesn't use Mac address ,uses only certain port number to accept the frame. But I have been read on book as well as internet that uses Mac address to find spanning tree for ...
S. M.'s user avatar
  • 398
0 votes
1 answer
159 views

Which interface will be the root port in this topology?

I am currently studying for my CCNA and the current topic is STP. I ran into this topology and it caused me some confusion. I was trying to identify the root port for SW2. Here was my logic for that. ...
Mitrixsen's user avatar
  • 803
-1 votes
1 answer
1k views

HP 6120XG switch LACP is blocked - error condition

Folks, I am dealing with very strange issue related LACP and not sure if its bug of 6120XG switch or something else. so let me explain my issue here. Network Diagram: I have two Cisco Nexus 9396PX ...
Satish's user avatar
  • 4,379
2 votes
3 answers
723 views

what is switch device mac address?

I'm studying STP protocol and how to configure STP on switches. I know each switch has several ports and each port has one MAC address. but when I read the below article I noticed that it allocate one ...
hamed's user avatar
  • 165
2 votes
3 answers
646 views

What is the behavior of two managed switches connected to one unmanaged switch?

Image the followign scenario Switch 1 Managed (root) Switch 2 Managed Switch 3 Unmanaged They are connected as follows: Switch 1 <-> Switch 3 Switch 2 <-> Switch 3 Switch 1 <-> ...
Kevin's user avatar
  • 23
3 votes
1 answer
1k views

RSTP / MSTP use cases and best practices

Hi, what would be the best practice to achieve separate tree topologies for each of the rings? Two options come to my mind, although I do not completely understand IF RSTP can be made VLAN-aware ...
WoyoC's user avatar
  • 33
2 votes
1 answer
313 views

Using PT and EtherChannels along with STP

I'm very new to all of this but I am trying to create a network topology as practice that uses three etherchannels across three switches and then rely on STP to block one. So far it was working well. ...
James's user avatar
  • 23
5 votes
2 answers
344 views

STP convergence process needs detailed explanation, please

So, I understand how STP convergence works on high-level. However, when I am trying to look into the process deeper, I run across some doubts I would appreciate someone could clarify to me. Here we go:...
just_a_noobie's user avatar
4 votes
2 answers
944 views

MSTP with different VLANs blocking port

I am trying to use MSTP with HP Procurve switches. The edge switch (D in diagram) has half of the ports set to VLAN10 and half set to VLAN20, all untagged. The problem is that the switch D to forward ...
yurtesen's user avatar
  • 143
5 votes
1 answer
358 views

STP frames over VPLS/VPWS

Do VPLS and VPWS services transfer STP frames? How about other L2 control frames? Can two geographically dispersed sites have one STP region over any L2VPN?
A.A's user avatar
  • 551
0 votes
2 answers
505 views

what is the main function of root bridge and ring master?

When we learn the STP or RSTP,we all learn the election of root bridge, the lowest priority number or MAC address of switch will become the root bridge.So here is my first question: 1.So what can the ...
user16266657's user avatar
1 vote
1 answer
468 views

Why does only the root bridge send RSTP BPDUs after sync?

From a recent packet capture, after the sync process in RSTP, only the root bridge sends RSTP BPDUs every 'hello' interval. Why is it so? Shouldn't all switches send BPDUs every 'hello' interval since ...
noobmaster69's user avatar
4 votes
0 answers
183 views

Why does RSTP send proposal bit and agreement bit as '1' initially?

From a recent Wireshark capture of a RSTP BPDU on a switch, both proposal and agreement bits were set to '1'. In my understanding, initially both switches 'propose' themselves as root. The better root ...
noobmaster69's user avatar
0 votes
2 answers
496 views

The difference between data frame and BPDU in STP

There are two of port states in STP: Disabled and Blocking,and the a website explain their difference Disabled : This port is shutdown,and it won't send or receive any frame Blocking : This port won't ...
user16266657's user avatar
4 votes
6 answers
1k views

Why does STP choose the lowest bridge ID as the root bridge?

The switch which has the lowest bridge ID can be the root bridge,and the bridge ID is made of priority and MAC address,that is , bridge ID = priority + MAC address So we will choose the switch which ...
user16266657's user avatar
2 votes
1 answer
168 views

STP Loop issue on long distance link

I have long distance connectivity between west coast to east cost datacenter via our ISP network as you can see that in following diagram (BSN=Boston, PHX=Phoenix) Now when ISP-A or ISP-B doing any ...
Satish's user avatar
  • 4,379
0 votes
2 answers
195 views

Ramifications of turning off Spanning Tree for EIGRP network?

Ran into something I've never seen before in a production network I'm new to supporting and wanted to get the communities take on it. I have an EIGRP network that interconnects about 60 sites across a ...
user68992's user avatar
0 votes
1 answer
41 views

How can a topology have a switch with 3 segments that are unblocked? (Spanning Tree Protocol)

I am quite confused after doing some research online regarding designated port selection. It looked like to me that each port segment has a designated port and a blocked port? If you look at the ...
scott-ws's user avatar
0 votes
2 answers
836 views

RSTP: Max Aging and Device Count

I have a question about the RSTP ethernet swtiches, I have 40 RSTP ethernet switches, they connect with the line topology and root birdge is 23th device on the line. I am using just 23 device for this ...
mathco's user avatar
  • 1
-1 votes
2 answers
333 views

RSTP Network Switches Port Base MAC Address

How to ethernet managable network switch manage the dynamic table entries although receive "port base MAC address frame" like RSTP,STP protocole ? I know the dynamic mac table save the ...
mathco's user avatar
  • 1
0 votes
1 answer
358 views

BPDU Guard With RSTP Devices

I am attempting to secure our switches with BPDU Guard. I have it enabled and I have a pieces of equipment with 2 NIC ports on them of which they can be daisy chained together for data collection. ...
JukEboX's user avatar
  • 461
1 vote
2 answers
626 views

Losing connection when connecting a server to Stratix 5400?

I have a problem that when connecting a server to Stratix 5400 the Stratix loses connection for some seconds which causes a Safety Fault for the line because we have Safety PLC’s any help. ,Software ...
Ali Saeed's user avatar
0 votes
1 answer
2k views

What are the differences between root primary and secondary?

Hello I am new at networking and studying for CCNA. There is a paragraph like this in the book and I am struggling about understanding well. Maybe it's because english is not my native language. ...
Red And Black's user avatar
0 votes
1 answer
415 views

How does STP attack work?

I was reading how STP works and an idea came to my mind. I thought about an attacker can add a new switch (somehow, i don't know if it can be done remotely) or can manipulate the existing switch's ...
Red And Black's user avatar
0 votes
1 answer
137 views

Layer 2 path selection

So i know this in stp domain if you want to influence traffic you. Eed to increase the port cost on the undesirable port for the desired vlan or mst instance and it worked for me,but on a non root ...
Micro-black-Hole's user avatar

1
2 3 4 5
7