user manual
Table Of Contents
- Cisco Nexus 3000 NX-OS Layer 2 Switching Configuration Guide, Release 5.0(3)U3(1)
- Contents
- Preface
- New and Changed Information for this Release
- Overview
- Configuring Ethernet Interfaces
- Information About Ethernet Interfaces
- Configuring Ethernet Interfaces
- Configuring the UDLD Mode
- Changing an Interface Port Mode
- Configuring Interface Speed
- Disabling Link Negotiation
- Configuring the CDP Characteristics
- Enabling or Disabling CDP
- Enabling the Error-Disabled Detection
- Enabling the Error-Disabled Recovery
- Configuring the Error-Disabled Recovery Interval
- Configuring the Debounce Timer
- Configuring the Description Parameter
- Disabling and Restarting Ethernet Interfaces
- Displaying Interface Information
- Displaying Input Packet Discard Information
- Default Physical Ethernet Settings
- Configuring VLANs
- Configuring Private VLANs
- Information About Private VLANs
- Guidelines and Limitations for Private VLANs
- Configuring a Private VLAN
- Enabling Private VLANs
- Configuring a VLAN as a Private VLAN
- Associating Secondary VLANs with a Primary Private VLAN
- Configuring an Interface as a Private VLAN Host Port
- Configuring an Interface as a Private VLAN Promiscuous Port
- Configuring a Promiscuous Trunk Port
- Configuring an Isolated Trunk Port
- Configuring the Allowed VLANs for PVLAN Trunking Ports
- Configuring Native 802.1Q VLANs on Private VLANs
- Verifying the Private VLAN Configuration
- Configuring Access and Trunk Interfaces
- Configuring Switching Modes
- Configuring Rapid PVST+
- Information About Rapid PVST+
- Understanding STP
- Understanding Rapid PVST+
- Rapid PVST+ and IEEE 802.1Q Trunks
- Rapid PVST+ Interoperation with Legacy 802.1D STP
- Rapid PVST+ Interoperation with 802.1s MST
- Configuring Rapid PVST+
- Enabling Rapid PVST+
- Enabling Rapid PVST+ per VLAN
- Configuring the Root Bridge ID
- Configuring a Secondary Root Bridge
- Configuring the Rapid PVST+ Port Priority
- Configuring the Rapid PVST+ Pathcost Method and Port Cost
- Configuring the Rapid PVST+ Bridge Priority of a VLAN
- Configuring the Rapid PVST+ Hello Time for a VLAN
- Configuring the Rapid PVST+ Forward Delay Time for a VLAN
- Configuring the Rapid PVST+ Maximum Age Time for a VLAN
- Specifying the Link Type
- Restarting the Protocol
- Verifying Rapid PVST+ Configurations
- Information About Rapid PVST+
- Configuring Multiple Spanning Tree
- Information About MST
- Configuring MST
- MST Configuration Guidelines
- Enabling MST
- Entering MST Configuration Mode
- Specifying the MST Name
- Specifying the MST Configuration Revision Number
- Specifying the Configuration on an MST Region
- Mapping and Unmapping VLANs to MST Instances
- Mapping Secondary VLANs to Same MSTI as Primary VLANs for Private VLANs
- Configuring the Root Bridge
- Configuring a Secondary Root Bridge
- Configuring the Port Priority
- Configuring the Port Cost
- Configuring the Switch Priority
- Configuring the Hello Time
- Configuring the Forwarding-Delay Time
- Configuring the Maximum-Aging Time
- Configuring the Maximum-Hop Count
- Configuring PVST Simulation Globally
- Configuring PVST Simulation Per Port
- Specifying the Link Type
- Restarting the Protocol
- Verifying MST Configurations
- Configuring STP Extensions
- About STP Extensions
- Information About STP Extensions
- Configuring STP Extensions
- STP Extensions Configuration Guidelines
- Configuring Spanning Tree Port Types Globally
- Configuring Spanning Tree Edge Ports on Specified Interfaces
- Configuring Spanning Tree Network Ports on Specified Interfaces
- Enabling BPDU Guard Globally
- Enabling BPDU Guard on Specified Interfaces
- Enabling BPDU Filtering Globally
- Enabling BPDU Filtering on Specified Interfaces
- Enabling Loop Guard Globally
- Enabling Loop Guard or Root Guard on Specified Interfaces
- Verifying STP Extension Configuration
- About STP Extensions
- Configuring LLDP
- Configuring the MAC Address Table
- Configuring IGMP Snooping
- Configuring Traffic Storm Control
- INDEX
BPDU version 0, the switch does not set the proposal flag and starts the forward-delay timer for the port. The
new root port requires twice the forward-delay time to transition to the forwarding state.
The switch interoperates with legacy 802.1D switches as follows:
• Notification—Unlike 802.1D BPDUs, 802.1w does not use TCN BPDUs. However, for interoperability
with 802.1D switches, Cisco NX-OS processes and generates TCN BPDUs.
• Acknowledgement—When an 802.1w switch receives a TCN message on a designated port from an
802.1D switch, it replies with an 802.1D configuration BPDU with the TCA bit set. However, if the
TC-while timer (the same as the TC timer in 802.1D) is active on a root port connected to an 802.1D
switch and a configuration BPDU with the TCA set is received, the TC-while timer is reset.
This method of operation is required only for 802.1D switches. The 802.1w BPDUs do not have the TCA bit
set.
• Protocol migration—For backward compatibility with 802.1D switches, 802.1w selectively sends 802.1D
configuration BPDUs and TCN BPDUs on a per-port basis.
When a port is initialized, the migrate-delay timer is started (specifies the minimum time during which 802.1w
BPDUs are sent), and 802.1w BPDUs are sent. While this timer is active, the switch processes all BPDUs
received on that port and ignores the protocol type.
If the switch receives an 802.1D BPDU after the port migration-delay timer has expired, it assumes that it is
connected to an 802.1D switch and starts using only 802.1D BPDUs. However, if the 802.1w switch is using
802.1D BPDUs on a port and receives an 802.1w BPDU after the timer has expired, it restarts the timer and
starts using 802.1w BPDUs on that port.
If you want all switches to renegotiate the protocol, you must restart Rapid PVST+.Note
Rapid PVST+ Interoperation with 802.1s MST
Rapid PVST+ interoperates seamlessly with the IEEE 802.1s Multiple Spanning Tree (MST) standard. No
user configuration is needed.
Configuring Rapid PVST+
Rapid PVST+, which has the 802.1w standard applied to the Rapid PVST+ protocol, is the default STP setting
in the software.
You enable Rapid PVST+ on a per-VLAN basis. The software maintains a separate instance of STP for each
VLAN (except on those VLANS on which you disable STP). By default, Rapid PVST+ is enabled on the
default VLAN and on each VLAN that you create.
Enabling Rapid PVST+
Once you enable Rapid PVST+ on the switch, you must enable Rapid PVST+ on the specified VLANs.
Rapid PVST+ is the default STP mode. You cannot simultaneously run MST and Rapid PVST+.
Cisco Nexus 3000 NX-OS Layer 2 Switching Configuration Guide, Release 5.0(3)U3(1)
78 OL-26590-01
Configuring Rapid PVST+
Rapid PVST+ Interoperation with 802.1s MST