Skip to main content

What are Inferior and Superior BPDUs of STP

Today i want to have a very brief talk about what the Spanning-Tree Inferior and Superior BPDUs are and what is the difference between them.
Inferior BPDU of STP
The BPDU is considered inferior, if it carries information about the root bridge that is worse than the one currently stored for the port, or the BPDU has longer distance to reach the current root bridge. Inferior BPDUs may appear when a neighboring switch suddenly loses its uplink and claims itself the new root of the topology. By default, every switch should ignore inferior BPDUs, until the currently stored BPDU expires (time=Max_Age – Message_Age). This feature intends to stabilize STP topology in situations where an uplink on some switch flaps (goes down and up frequently for any malfunction), causing the switch to start sending inferior informationSuperior BPDU of STP
A superior BPDU is one that has a lower Bridge ID. An inferior BPDU would have a higher Bridge ID. This can’t be judged on a single BPDU basis. It’s only in comparison that one can be considered superior or inferior. Receiving a superior BPDU typically means that a switch received a BPDU with a lower Bridge ID than the Bridge ID of the currently elected root bridge.
If a switch receives an inferior BPDU, nothing changes. Receiving a superior BPDU will kick off a reconvergence of the STP topology.

Comments

Popular posts from this blog

What is Cisco Supervisor Engine?

Supervisor Engine is a module that is installed in the Cisco Chassis-based Catalyst Switches or Routers. Supervisor engine contains nearly all the same components of a fixed Cisco Switches or Routers. These Supervisor engines come in a variety of different types with different functionalities and are installed in the Switches/Router Chassis as per requirements of the network types.

Benefits of Supervisor Engines
By installing Latest Supervisor Engines in your existing investments (Switches and Routers) you can scale system performance and integrate next-generation services into your Networks.
Within a single multilayer switch chassis, two supervisor modules with integrated route processors can be used to provide hardware redundancy. If an entire supervisor module fails, the other module can pick up the pieces and continue operating the switch.
The supervisor engine contains the following integrated daughter cards that perform forwarding and routing and provide the protocols supported …

GNS3 Docker Error while creating node: Docker has returned an error: Cannot connect to host docker:80

Error while creating node: Docker has returned an error: Cannot connect to host docker:80 ssl:False [No such file or directory]

After adding docker template for Alpine Linux in gns3, you get above mentioned message when you want to use alpine linux in GNS3.

To get rid of this message you have to install Docker by following below link
curl -fsSL https://get.docker.com/ | sh

If you do not have curl installed then instal curl first with below command.apt-get install curl
After installing Docker you need to add your user name in the docker group with the following command. $ sudo usermod -aG docker your_username

Verify if the docker service is started with following command$ service docker status
If docker is not started then start with following command $ sudo service docker start
Logout from GNS3 Virtual Machines and log back. Start gns3 and use alpine linux.

Telnet Client is Disabled Enable it to use it from this application

This is a Cisco Network Assistant (CNA) error when you want to telnet any Cisco Devices from within CNA.
Solution to remove this error is related to Windows 7 or Windows Vista. First of all you need to Add TELNET program from Control Panel, which by Default is not added in fresh installation of Windows 7.For adding and using Telnet Program in Windows 7, Click Start > Control Panel > Uninstall a Program > Turn Windows Features On and OFF > Scroll to TELNET and Select it > Press OK After Adding Telnet Program into the Windows 7 you need to Copy Telent.exe from C:\Windows\System32 folder and paste it to C:\Windows\SysWOW64\ Now you should not get the same error.