You need to configure spanning tree on a cisco switch

You need to configure spanning tree on a cisco switch verification#
You need to configure spanning tree on a cisco switch mac#

You need to configure spanning tree on a cisco switch verification#

Finally we looked at some of the verification and troubleshooting commands. In this chapter, we have looked at the configuration and verification of STP, we configured and verified the BID options, and we also configured CISCO portfast. These concepts will be discussed in detail in the last part of this chapter on STP. In this course, we will mostly focus on the PVST variations and RSTP. The table below shows the various STP implementation variants. In this section we will learn about other variants of STP such as RSTP, PVST+ and others, some of these are CISCO proprietary while others are open standards defined by IEEE. So far we have learnt about the 802.1d implementation of STP. NOTE: other verification and troubleshooting commands will be discussed in more detail in advanced courses such as CCNP, however, you are supposed to understand the commands discussed above well.

The show spanning-tree interface will show similar output to the show spanning-tree VLAN and show spanning-tree active however, it will focus on the specific interface that is prompted.

The show spanning-tree vlan will show the variant of STP running on a various VLAN, it will tell you whether a switch is the root bridge for the specific VLAN and the operational status of the ports on the switch for the that VLAN.

The other verification commands can be used to operate the operation of STP. Will tell you most of the spanning tree statistics that you need to know to determine the root bridge and the other switch roles. This is the command used to verify which switch is the root bridge. NOTE: the root bridge will have the same root id and bridge id values. Some of the statistics include the type of STP, in this case it is 802.1D which is the open STP standard, the VLANs which have STP, the port roles and the priority, and you can also verify the bridge ID. The output of this command will show the active STP instances on a switch as shown below. For this we will use the commands shown below. We need to verify the operation of STP on the switches. When this command is executed, the access ports will transition immediately from blocking to forwarding state and no BPDUs will be sent to these interfaces. The CISCO portfast technology was discussed in part 1 of this chapter, to configure portfast on access ports, enter the following command in the access ports on a switch: These commands will change the priorities of all normal VLANs on the four switches to the configured value. In our case we will use the priority command on all the switches and the commands used are shown below. NOTE: by default the spanning tree priority is 32778 To configure a switch to be the Root Bridge of a Spanning Tree network, you must modify the Bridge ID of the switch to be the lowest among all the switches. This command is also configured per VLAN. The spanning tree command is a component of the BID and it is a value from 0 вЂ“ 61440, the priority is any number in this range in multiples of 4096, this means that you cannot use a value like 200.

The second command that can be used is the priority command.

The command is used in the global configuration mode. Most junior networkers approach STP as a 'the defaults should be fine' kind of technology.ДЄnd that approach will work fine for two or three switches.Д«ut if you have dozens of switches, or if you have especially high requirements for stability & performance, then the defaults just aren't acceptable.Use the root primary and secondary вЂ“ this can be used to specify which switch will be the root bridge and the secondary.

If it is simple and predictable, it is easier to troubleshoot & diagnose if it ever becomes unstable.ДЄnd those two accomplishments (stable & easy to fix) are pretty much all we can hope for when dealing with STP.Дisabling STP everywhere does not achieve stability, nor easy of troubleshooting, nor predictability in troubleshooting. If it is simple and predictable, it will be stable.

My approach & guidance focuses almost exclusively on building a clear and predictable STP topology.

You need to configure spanning tree on a cisco switch mac#

So the tree will build itself using the lowest MAC Address as the root, which can lead to some really crazy and unexpected STP topologies. But they are all set to the same priority. If you configure spanning-tree portfast on a port, it will give you a warning saying that this port should not be connected to a switch & similar other. I don't see anyone speaking in favor if disabling or removing STP.Д«ut I do see others venting or commiserating that they too have had to deal with network instability caused by sub-optimal STP configurations.Д«y default, out of the box, all switches have STP enabled. I just re-read that thread to make sure I hadn't missed something.