Prerequisites For Stp Extensions; Guidelines And Limitations For Configuring Stp Extensions - Cisco Nexus 7000 Series Configuration Manual

Configuring STP Extensions Using Cisco NX-OS

Prerequisites for STP Extensions

STP has the following prerequisites:
• You must be logged onto the device.

Guidelines and Limitations for Configuring STP Extensions

STP extensions have the following configuration guidelines and limitations:
• Connect STP network ports only to switches.
• You should configure host ports as STP edge ports and not as network ports.
• If you enable STP network port types globally, ensure that you manually configure all ports connected
• You should configure all access and trunk ports connected to Layer 2 hosts as edge ports.
• Bridge Assurance runs only on point-to-point spanning tree network ports. You must configure each
• We recommend that you enable Bridge Assurance throughout your network.
• We recommend that you enable BPDU Guard on all edge ports.
• Enabling Loop Guard globally works only on point-to-point links.
• Enabling Loop Guard per interface works on both shared and point-to-point links.
• Root Guard forces a port to always be a designated port; it does not allow a port to become a root port.
• Loop Guard has no effect on a disabled spanning tree instance or a VLAN.
• Spanning tree always chooses the first operational port in the channel to send the BPDUs. If that link
• If you group a set of ports that are already blocked by Loop Guard to form a channel, spanning tree loses
• If a channel is blocked by Loop Guard and the channel members go back to an individual link status,
• You should enable Loop Guard globally on a switch network with physical loops.
• You should enable Root Guard on ports that connect to network devices that are not under direct
• If you configure the spanning-tree forward-delay time to below the default value, it can impact the
to hosts as STP edge ports.
side of the link for this feature.
Loop Guard is effective only if the port is a root port or an alternate port. You cannot enable Loop Guard
and Root Guard on a port at the same time.
becomes unidirectional, Loop Guard blocks the channel, even if other links in the channel are functioning
properly.
all the state information for those ports and the new channel port may obtain the forwarding state with
a designated role.
spanning tree loses all the state information. The individual physical ports may obtain the forwarding
state with the designated role, even if one or more of the links that formed the channel are unidirectional.
administrative control.
system's ability to successfully perform a switchover supervisor at scale.
Cisco Nexus 7000 Series NX-OS Layer 2 Switching Configuration Guide, Release 5.x

Prerequisites for STP Extensions

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