Apply MSTP Basic Functions in MLAG Environment

Network Requirements

• The four devices in the network are all in the same MST domain, and the bridge priority of the MLAG device is the highest.

Network Topology

Figure 9-2 Networking for the application of MSTP in MLAG

Configuration Steps

Step 1: Add the interface to the aggregation group and add to the VLAN. (omitted)

Step 2: Configure the MLAG domain. (omitted)

Step 3: Configure the MST domain.

#Configure the MST domain on Device1, configure the domain name as admin and the revision level as 1 to activate the MST domain.

• ---

  The MST domain configuration of Device2, SD, and DHD is the same as Device1. (omitted)

  ---

   

View the details of each device spanning tree.

#Aggregation 1 on Device1 and Device2 is the interconnection port.

Device1#show spanning-tree  
Spanning-tree enabled protocol mstp 
MST Instance 00	vlans mapped: 1-4094 
Bridge	            address 0001.7a95.000b priority 0 
Region root	    	address 0001.7a95.000b priority 0
Designated root		address 0001.7a95.000b priority 0 
                        root: 0, rpc: 0, epc: 0, hop: 20 
                        We are the root of the spanning tree
Operational hello time 2, forward time 15, max age 20, message age 0 
Configured hello time 2, forward time 15, max age 20, max hops 20, hold count 10
Flap guard : admin false, max count 5, detect period 10s, recovery period 30s 
Tc protection: admin true, threshold 2, interval 20s, rxTcCnt 0, status:NORMAL
ARL flush: enabled 
Bpdu length-check: false, bpdu illegal length packets count: 0
Autoedge swap-check: true 
Swap-delay time: 30
Configured timer factor: 3 
Topology Change Count:6, last change occured:118 weeks 5 days(71863322 seconds)
Interface	     Role Sts   Cost	 Prio.Nbr  Type	 
-------------------------------------------------
te0/1	  	     Desg FWD   20000	 128.0036  P2P  
link-agg1		 Desg FWD   1950	 128.0193  P2P (MLAG peer-link)  
link-agg30		 Desg FWD   19500	 128.0222  P2P (MLAG 100) 
 			
Device2#show spanning-tree
Spanning-tree enabled protocol mstp 
MST Instance 00	        vlans mapped: 1-4094 
Bridge              	address 0001.7a95.000b priority 0 
Region root		        address 0001.7a95.000b priority 0
Designated root	    	address 0001.7a95.000b priority 0 
                            root: 0, rpc: 0, epc: 0, hop: 20 
                            We are the root of the spanning tree
Operational hello time 2, forward time 15, max age 20, message age 0 
Configured hello time 2, forward time 15, max age 20, max hops 20, hold count 6
Flap guard : admin false, max count 5, detect period 10s, recovery period 30s 
Tc protection: admin true, threshold 1, interval 4s, rxTcCnt 0, status:NORMAL
ARL flush: enabled 
Bpdu length-check: false, bpdu illegal length packets count: 0
Autoedge swap-check: true 
Swap-delay time: 30
Configured timer factor: 3 
Topology Change Count:7, last change occured:118 weeks 4 days(71776558 seconds)
Interface	  Role Sts   Cost	 Prio.Nbr  Type	  
------------------------------------------------	  	  	  	 
gi0/1	     Desg FWD    20000	 128.0332  P2P  
link-agg1	 IRoot FWD   1950	 128.0385  P2P (MLAG peer-link)  
link-agg30	 Desg FWD    19500	 128.0414  P2P (MLAG 100) 

#SD connects the port of Device2 and the spanning tree calculation is block, and the mlag-group of DHD is Root.

SD#show spanning-tree  
Spanning-tree enabled protocol mstp 
MST Instance 00	           vlans mapped: 1-4094 
Bridge	address            0001.7a7a.3c10 priority 32768 
Region root		           address 0001.7a95.000b priority 0
Designated root		       address 0001.7a95.000b priority 0 
                              root: 32804, rpc: 20000, epc: 0, hop: 19
Operational hello time 2, forward time 15, max age 20, message age 0 
Configured hello time 2, forward time 15, max age 20, max hops 20, hold count 6
Flap guard : admin false, max count 5, detect period 10s, recovery period 30s 
Tc protection: admin true, threshold 1, interval 4s, rxTcCnt 0, status:NORMAL
ARL flush: enabled 
Bpdu length-check: false, bpdu illegal length packets count: 0
Autoedge swap-check: true 
Swap-delay time: 30
Configured timer factor: 1 
Topology Change Count:36, last change occured:118 weeks 5 days(71863036 seconds)
Interface	Role Sts  Cost	 Prio.Nbr Type	  
---------------------------------------------	  	  	  	  	 
gi0/1	    Root FWD  20000	 128.0012 P2P  
gi0/2	    Alte DIS  20000	 128.0036 P2P  
		 
DHD#show spanning-tree  
Spanning-tree enabled protocol mstp 
MST Instance 00	          vlans mapped: 1-4094 
Bridge	address           0001.7a6a.0148 priority 32768 
Region root		          address 0001.7a95.000b priority 0
Designated root		      address 0001.7a95.000b priority 0 
                              root: 33662, rpc: 18000, epc: 0, hop: 19
Operational hello time 2, forward time 15, max age 20, message age 0 
Configured hello time 2, forward time 15, max age 20, max hops 20, hold count 6 
Flap guard : admin false, max count 5, detect period 10s, recovery period 30s
Tc protection: admin true, threshold 1, interval 4s, rxTcCnt 0, status:NORMAL
ARL flush: enabled 
Bpdu length-check: false, bpdu illegal length packets count: 0
Autoedge swap-check: true 
Swap-delay time: 30
Configured timer factor: 6 
Topology Change Count:20, last change occured:118 weeks 5 days(71863409 seconds) 
Interface	Role Sts  Cost	 Prio.Nbr Type
---------------------------------------------	  	  	  	  	  	 
link-agg30	Root FWD  18000	 128.0894 P2P 

Step 4: Modify the priority of the specified bridge of Device2, so that the blocked port of SA is calculated as 0/1.