What is a loop guard?
What is a loop guard?
Loopguard provides additional protection against Layer 2 forwarding loops (spanning tree loops). A spanning tree loop is created when a spanning tree blocking port, in a redundant topology, erroneously transitions to the forwarding state. Best practices is that loopguard be used on non-designated ports.
What is root guard?
Root guard is an STP feature that is enabled on a port-by-port basis; it prevents a configured port from becoming a root port. Root guard prevents a downstream switch (often misconfigured or rogue) from becoming a root bridge in a topology. Root guard is enabled with the interface command spanning-tree guard root.
What is the difference between RSTP and Pvst?
The RSTP is an improvement on the spanning tree protocol, and it is a standard spanning tree as an IEEE standard while the PVST is a spanning tree protocol as a Cisco proprietary. PVST is the Cisco counterpart of IEEE’s RSTP. PVST is usually used on VLANS (or Virtual Local Area Network) while RSTP is often used in LAN.
What does the root bridge do?
As shown in Figure 3-8, every spanning-tree instance (STP instance) has a switch designated as the root bridge. The root bridge serves as a reference point for all spanning-tree calculations to determine which redundant paths to block. An election process determines which switch becomes the root bridge.
How do I disable loop guard?
To globally disable loop guard, use the no spanning-tree loopguard default global configuration command. You can override the setting of the no spanning-tree loopguard default global configuration command by using the spanning-tree guard loop interface configuration command on an NNI.
What is BPDU loop guard?
The loop guard feature checks if a root port or an alternate root port receives BPDUs. If the port is receiving BPDUs, the loop guard feature puts the port into an inconsistent state until it starts receiving BPDUs again.
Where do you use root guard?
Root Guard feature can be enabled on switch ports that is connected to other switches that should never become a Root Bridge. For example, a port on the distribution layer switch which is connected to an access layer switch can be Root Guard enabled, because the access layer switch should never become the Root Bridge.
How do you use root guard?
Configure the Root Guard
- Enter Configuration mode for the interface. SEFOS# configure terminal SEFOS(config)# interface extreme-ethernet 0/1.
- Configure the port as a trunk port.
- Enable the root guard on the port.
- Review the root guard output on the port.
- Disable the root guard on the interface.
What is the difference between Pvst and rapid Pvst?
The difference between RSTP and PVST is that RSTP aka Rapid Spanning Tree Protocol (RSTP) enables much quicker spanning-tree resolution following a topology change when compared to PVST which is custom owned by Cisco. IEEE 802.1D is the specification for RSTP.
Are RSTP and Pvst compatible?
It is possible to mix PVST and MST (RSTP requires MST), but it needs some planning, and it can be fragile, as you have discovered. You would probably be better off using the same STP version across all your switches. You could change the STP on the Cisco switches to match the rest of the switches.
Which switch should be root bridge?
The switch with the lowest priority becomes the root bridge. If there’s a tie, then the switch with the lowest bridge ID number wins. The ID number is typically derived from a MAC address on the switch.
What makes a switch a root bridge?
An election process determines which switch becomes the root bridge. Each switch has a Bridge ID (BID) that is made up of a priority value, an extended system ID, and the MAC address of the switch. All switches in the network take part in the election process.
What is loop guard in Linux?
Loop guard detects root ports and blocked ports and ensures that they keep receiving BPDUs from their designated port on the segment. If a loop guard enabled root or blocked port stop a receiving BPDUs from its designated port, it transitions to the loop-inconsistent blocking state, assuming there is a physical link error on this port.
What is the difference between STP root guard and loop guard?
Usually STP root guard is configured on primary & secondary root switches. You can configure this per interface level as shown in the below. Loop guard helps prevent bridging loops that could occur because of a unidirectional link failure on a point-to-point link.
What is the difference between BPDU guard and root guard?
BPDU guard and Root guard are similar, but their impact is different. BPDU guard disables the port upon BPDU reception if PortFast is enabled on the port. The disablement effectively denies devices behind such ports from participation in STP.
What is root guard and how does it work?
Root guard allows the device to participate in STP as long as the device does not try to become the root. If root guard blocks the port, subsequent recovery is automatic. Recovery occurs as soon as the offending device ceases to send superior BPDUs
