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Saturday, February 2, 2013

forwarding, not pruned...

you love show interface trunk, because i said you do...

DLS2#sh int trunk                                                              
                                                                               
Port        Mode             Encapsulation  Status        Native vlan          
Po2         on               802.1q         trunking      900                  
Po10        on               802.1q         trunking      900                  
                                                                               
Port        Vlans allowed on trunk                                             
Po2         10,20,30,100                                                       
Po10        10,20,30,50,100                                                    
                                                                               
Port        Vlans allowed and active in management domain                      
Po2         10,20,30,100                                                       
Po10        10,20,30,50,100                                                    
                                                                               
Port        Vlans in spanning tree forwarding state and not pruned             
Po2         10,20,30,100                                                       
Po10        10,20,30,50,100                   

note vlan 50 is not forwarding on po2...

DLS2#sh run int po2                                                            
Building configuration...                                                      
                                                                               
Current configuration : 223 bytes                                              
!                                                                              
interface Port-channel2                                                        
 description Channel to ALS1                                                   
 switchport trunk encapsulation dot1q                                          
 switchport trunk native vlan 900                                              
 switchport trunk allowed vlan 10,20,30,100                                    
 switchport mode trunk                                                         
 switchport nonegotiate             

as you can see that's by design... however it is forwarding on po10 although it is down...

DLS2#sh int vlan 50                                                            
Vlan50 is administratively down, line protocol is down                         
  Hardware is EtherSVI, address is 0016.479e.5fc6 (bia 0016.479e.5fc6)         
  Internet address is 10.1.50.253/24        

DLS2#sh spann vlan 50 | b Interface
Interface           Role Sts Cost      Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------
Po10                Desg FWD 12        128.128  P2p

spanning tree believes it is still forwarding simply because it's allowed on the trunk regardless of it's operational state...

DLS2#sh run int po10
Building configuration...

Current configuration : 227 bytes
!
interface Port-channel10
 description Channel to DLS1
 switchport trunk encapsulation dot1q
 switchport trunk native vlan 900
 switchport trunk allowed vlan 10,20,30,50,100
 switchport mode trunk
 switchport nonegotiate

of course dls1 can't ping it and it's getting no hsrp love...

DLS1>ping 10.1.50.253                                                           
                                                                                
Type escape sequence to abort.                                                  
Sending 5, 100-byte ICMP Echos to 10.1.50.253, timeout is 2 seconds:            
.....                                                                           
Success rate is 0 percent (0/5)                                                 
DLS1>sh stand brie                                                              
                     P indicates configured to preempt.                         
                     |                                                          
Interface   Grp  Pri P State   Active          Standby         Virtual IP       
Vl10        10   110 P Active  local           10.1.10.253     10.1.10.254      
Vl20        20   100 P Standby 10.1.20.253     local           10.1.20.254      
Vl30        30   110 P Active  local           10.1.30.253     10.1.30.254      
Vl50        50   100 P Active  local           unknown         10.1.50.254      
Vl100       100  110 P Active  local           10.1.100.253    10.1.100.254 

hsrp was nice enough to take over on dls1, however...

DLS2#sh stand brie                                                              
                     P indicates configured to preempt.                         
                     |                                                          
Interface   Grp  Pri P State   Active          Standby         Virtual IP       
Vl10        10   100 P Standby 10.1.10.252     local           10.1.10.254      
Vl20        20   110 P Active  local           10.1.20.252     10.1.20.254      
Vl30        30   100 P Standby 10.1.30.252     local           10.1.30.254      
Vl50        50   110 P Init    unknown         unknown         10.1.50.254      
Vl100       100  100 P Standby 10.1.100.252    local           10.1.100.254

once i disallow it on the trunk:

DLS2#sh spann vlan 50                                                           
                                                                                
Spanning tree instance(s) for vlan 50 does not exist.

it stops showing up in forwarding state...

DLS2#sh int trunk                                                               
                                                                                
Port        Mode             Encapsulation  Status        Native vlan           
Po2         on               802.1q         trunking      900                   
Po10        on               802.1q         trunking      900                   
                                                                                
Port        Vlans allowed on trunk                                              
Po2         10,20,30,100                                                        
Po10        10,20,30,100                                                        
                                                                                
Port        Vlans allowed and active in management domain                       
Po2         10,20,30,100                                                        
Po10        10,20,30,100                                                        
                                                                                
Port        Vlans in spanning tree forwarding state and not pruned              
Po2         10,20,30,100                                                        
Po10        10,20,30,100     

and until it is added to the trunk, although it is no longer shut, it is up, down because it is not an active member of any port...

DLS2#sh int vlan 50                                                             
Vlan50 is up, line protocol is down                                             
  Hardware is EtherSVI, address is 0016.479e.5fc6 (bia 0016.479e.5fc6)          
  Internet address is 10.1.50.253/24                                 

the point is it doesn't get pruned from the trunk, until it is taken out of allowed manually... allowed prevents dynamic pruning... makes sense...

DLS2(config)#int po10                                                           
DLS2(config-if)#sw trunk allowed vlan 10,20,30,50,100                           
DLS2(config-if)#                                                                
Jan 22 23:59:11: %LINEPROTO-5-UPDOWN: Line protocol on Interface Vlan50, changedp
Jan 22 23:59:13: %HSRP-5-STATECHANGE: Vlan50 Grp 50 state Listen -> Active      
DLS2(config-if)#do sh int trunk                                                 
                                                                                
Port        Mode             Encapsulation  Status        Native vlan           
Po2         on               802.1q         trunking      900                   
Po10        on               802.1q         trunking      900                   
                                                                                
Port        Vlans allowed on trunk                                              
Po2         10,20,30,100                                                        
Po10        10,20,30,50,100                                                     
                                                                                
Port        Vlans allowed and active in management domain                       
Po2         10,20,30,100                                                        
Po10        10,20,30,50,100                                                     
                                                                                
Port        Vlans in spanning tree forwarding state and not pruned              
Po2         10,20,30,100                                                        
Po10        10,20,30,50,100               

DLS2(config-if)#do sh spann vlan 50 | b Int                                     
Interface           Role Sts Cost      Prio.Nbr Type                            
------------------- ---- --- --------- -------- --------------------------------
Po10                Desg FWD 12        128.128  P2p  

      

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