Enhanced Spanning Tree Protocol Note (BCMSN)

802.1D is a standard Spanning Tree Protocol (using CST and sharing a common STP). 802.1W is an enhanced Spanning Tree Protocol. The multi-Spanning Tree Protocol region is 802.1 s (using MST ). The rapid generation Tree Protocol (RSTP) can quickly converge and stabilize the network.

Three special functions:
PortFast can only be used for access ports (access ports) in this status. It can quickly change from block to forward to accelerate the generation tree convergence time.
Plinkfast (fast uplink) is used for access layer switches. A non-root switch in this state can quickly become a forward state when the root port fails, instead of going through the listen and learn statuses.
Using Backbonefast in all vswitches can accelerate network convergence, and it takes only 30 seconds for the port to switch from blocking to forwarding. Working principle: When the switch receives an inferior bpdu from the neighboring switch and claims that it is the bpdu of the root switch, the original link is faulty. Then the vswitch uses other available chains

Send the root link query bpdu to the root switch. If the root switch is reachable, the root switch will declare its existence to the switch in the network. First, the port that receives the inferior bpdu is quickly changed to the forward status, and the max age time is omitted.

Rapid tree Generation protocol (rapid spaning tree protocol): 802.1w is developed by 802.1d. This protocol can converge the network more quickly when the network structure changes. It has two more port types than 802.1d: standby port type alternate port) and backup port type.

Comparison:
(Standard) Disable, block, listen, learn, and forward.
(FAST) discard, learn, and forward
Full Duplex ---- point-to-point link type
Half Duplex ---- shared link type
Multi-Spanning Tree Protocol region: 802.1 s

If all the vswitches adopt the same configuration, they are called regions. They all know which VLANs are used and which spanning trees are used in the network.

The region has an association table including name, configuration version number, spanning tree, and VLAN.

Ist instances internal build tree

Configure the enhanced Spanning Tree Protocol:
1. Configure the quick port Function
2. Configure the fast uplink function to provide fast fault recovery
3. Configure the quick backbone function to provide fast fault recovery in the Core Module
4. Configure and verify Multiple Spanning Trees
5. Master the port aggregation method and configure the Fast Ethernet channel and gigabit channel to form a fast connection.
Spanning-tree portfast port Function
Spanning-tree uplinkfast [max-update-rate max_update_rate] configure the fast uplink Function
Show spanning-tree uplinkfast check whether uplinkfast is activated
Spanning-tree backbonefast
Show spanning-tree backbonefast
Spanning-tree mode mst activates a multi-Spanning tree instance. This command must be configured for all switches in the domain.
Spanning-tree mst configuration related to the multi-Spanning tree Protocol
Name name Domain Name
Revision rev_num configuration version
Instance inst vlan range associates the Spanning Tree Instance with the VLAN range
Show spanning-tree mst configuration view multi-spanning tree instance configuration

Ethernet channel: the same link can be bundled to form a higher-speed link. As a link, it can increase the link bandwidth and balance the load, providing redundancy. Configuration:
Inte *** ce port-channel-number (Layer 3) create Layer 3 Logical channel Interface
Ip address mask (layer-3) Configure Ip addresses for layer-3 Channel interfaces
Inte *** ce inte *** ce slot/port (Layer 2)
Channel-group number mode {auto | desirable | on} (Layer 2)
Show running-config inte *** ce port-channel num view layer-3 Logical channel Interface
Show running-config inte *** ce x/y view layer 2 physical port Channel Configuration
Show etherchannel num port-channel to view the status of a channel

Port aggregation protocol (PAgP, CISCO private, used by default) and link aggregation protocol (LACP)
PAGP: switches PAGP packets between two adjacent switches and binds the same link.
LACP: binds the same link to form a link with a higher speed.
Channel-protocol {lacp | pagp} interface mode specifies which Channel protocol the port uses
Lacp port-priority priority_value specifies the port priority.
Lacp system-priority priority_value specifies the priority of the switch (Global Mode)
Port-channel load-balance type specifies the load balancing mode used for the link status: mac-based and source-based and destrination ip.

Related Articles]

• Introduction to Spanning Tree Protocol
  

• Understanding the topology changes of the Spanning Tree Protocol
  

• Lecture 5: Learning Spanning Tree Protocol