12
votes
Accepted
Should I disable STP on my access ports?
You really, really do not want to disable STP where you connect switches to other switches. That is the entire purpose of STP. If you disable STP, and there is a problem, it will really be too late ...
- 98.3k
11
votes
Accepted
Do layer 3 protocols use layer 2 protocols?
Layer 3 (mostly IP) generally relies on the underlying layer-2 network (mostly Ethernet or Wi-Fi) for delivery. Just like a layer-2 network uses layer-1 links to actually move the bits.
The ...
- 81.5k
10
votes
Accepted
Does Switch need its own MAC address?
The basic function of a switch is transparent bridging - for this, it doesn't need any MAC address of its own.
However, if you need to talk to a switch - ie. a managed switch - then that switch ...
- 81.5k
9
votes
Accepted
STP blocking port selection
you need to understand the next
Spanning-Tree Port Roles
- Root Port (RP) - It is a port on a non-root switch, which is the shortest (the best) path towards the root bridge. (i.e. port 0/4 0/3 in ...
- 3,444
9
votes
Manager states we cannot put retail switches on network due to fear of non-STP config and network storm problems. Is this true?
Great question!
This is because a layer-2 switching loop can form on the Consumer-grade switching equipment which could produce Broadcast Radiation and impact devices connected to the broadcast ...
- 1,241
9
votes
I have a single ethernet switch. Should I use spanning tree?
To add to Zac67's and JFL's answers:
In case you decide to enable spanning-tree on the single switch, don't forget to configure the client's and server's switchports as Edge Ports (Cisco speak; ...
- 8,674
9
votes
Accepted
Fastest spanning tree in multiple-ring topology
MSTP and RSTP converge equally fast, MSTP is the current protocol version. Given the topology in your diagram (ugh!) and its tree depth, no STP variant will converge quickly (if at all).
xSTP default ...
- 81.5k
8
votes
Accepted
When and where to use Spanning-Tree (Portfast)
Spanning tree only runs between switches, never to standard end hosts.
Bear in mind that, under normal circumstances, a port supporting spanning tree will (when it first comes up) run through a ...
- 6,104
8
votes
Accepted
spanning-tree port type edge trunk on port-channel vs physical interface
Strongly suggested: Configure both port-channel and its members identically (except of course for description and the channel-group and vpc bits).
As long as an interface is not configured to be ...
- 8,674
8
votes
Accepted
Two switches, double connection, no LACP: how does it work?
Most likely, the rapid or the multiple spanning tree protocol RSTP/MSTP has been activated on the 1910 switch.
With the unmanaged 1410 switch forwarding STP BPDUs (most do), the 1910 notices a loop to ...
- 81.5k
7
votes
Accepted
Current Mode Spanning Tree
That will depend on the switch vendor, switch model, and software version which the switch is running.
When a new standard emerges, it can take some vendors a while to update their code to support ...
- 98.3k
7
votes
STP blocking port selection
Some corrections to the above answer. Port-id and port-priority are different. One is configurable. The other is internally set. I'll make an attempt to answer your question below.
There has to be ...
- 585
7
votes
Will STP lose data whilst switching from a failed link?
If i remember, default spanning tree (802.1d) takes about 50 secs to reconverge. That is the duration for which you will be losing frames.
A link is detected down by the loss of 10 hello pkts. These ...
- 585
7
votes
Multiple spanning tree terminology (CST/IST/CIST) and exact behavior
Now what exactly are the CST, the IST, and the CIST? Can someone draw me a simple MSTP topology with CST in red, IST in yellow, and CIST in green, so as to have a final reference without any ambiguous ...
- 9,381
7
votes
Accepted
I'm confused on how spanning tree works
Yes it did make him go through a more costly path. Maybe you aren't confused on how it works, maybe you're confused on what it's for?
Spanning-tree is for stopping network loops. It finds short paths ...
7
votes
Accepted
H3C MST BPDU exchange failing
You have a fundamental problem with your configuration, which is that the configuration digests on core and access switches don't match.
[Core-sw]dis stp region-configuration
Oper Configuration
...
- 1,568
7
votes
Is Per Vlan Spanning Tree or RPVST an open standard or can it only be implemented by Cisco?
(R)PVST(+) is a proprietary standard defined by Cisco (or a set thereof). However, there are many other vendors and devices supporting it - you may need to check the specifications of your devices.
...
- 81.5k
7
votes
Accepted
spanning tree RootGuard question on vPC switches
Based on the comments I think you are confused about guard root. You configure guard root on the downstream interfaces of all the switches, except the root switch. Basically, you are trying to protect ...
- 98.3k
7
votes
Fastest spanning tree in multiple-ring topology
If you can use Cisco Metro Ethernet switches, you might consider Resilient Ethernet Protocol, which is designed for ring topologies.
REP is a protocol used in order to replace the Spanning Tree ...
- 66.9k
7
votes
Do I need STP enabled on all switches in a loop?
Generally, a ring is a bad design for Ethernet switches. STP blocks one of the ring links, forming a chain. Traffic between switches on opposite sides need to cross the whole chain, potentially ...
- 81.5k
7
votes
Two switches, double connection, no LACP: how does it work?
Most switches comes with Spanning Tree (STP) enabled by default.
This protocols will detect the loop and disable one of the link to break it.
The new switch you connect either has STP disabled or a ...
- 19.4k
6
votes
Accepted
Will STP lose data whilst switching from a failed link?
It is possible, even likely, that at least one (probably more) frames will be lost on any failover.
The speed of the failover is highly dependent on what type of redundancy you are using. Spanning ...
- 98.3k
6
votes
Accepted
Spanning-Tree Interoperability between ProCurve core & Cisco access layer
Cisco PVST uses a non-standard destination MAC for BPDUs on all VLANs, so HP will not understand it. To the Cisco switch, it is the only switch on VLANs 2-14, which is why it thinks it is the root.
...
- 66.9k
6
votes
Accepted
Which switch MAC addresses are used for the Bridge ID in STP?
Which MAC address of this new switch will be used for the Bridge ID of
VLAN 15? Will that Bridge ID be used in the Root Bridge election for
VLAN 15?
According to Cisco:
MAC Addresses for ...
- 98.3k
6
votes
Accepted
Cisco: err-disabled due to loop - but there are NO redundant physical paths/ wires/ connections
I think this might be related to a bug. This issue is documented in Cisco bug ID CSCea46385.
To resolve the issue, you need to add the no keepalive command to the interface.
Hope this helps you on ...
- 2,016
6
votes
Accepted
Does the System ID Extension ever affect root bridge election?
Benjamin Dales answer is certainly correct for switches running standards based spanning tree. For switches using per VLAN STP however: yes, it can very well make a difference. Granted, under rather ...
- 1,049
6
votes
Accepted
Building too large for ethernet runs
Fiber is not so expensive unless you are getting fleeced. Indeed, it can be cheaper than copper cabling. It's also the right solution to long runs.
Given the installation costs, it's likewise foolish ...
- 2,746
6
votes
Best way to connect VLANs / STP / LAG
VLANs are a way of partitioning a given network into distinct layer 2 segments as if you'd be using separate switches, so you don't have your whole network bunched together. The advantage of VLANs ...
- 81.5k
Only top scored, non community-wiki answers of a minimum length are eligible