From: dagbo (goddardtek@nc.rr.com)
Date: Mon Feb 26 2007 - 22:26:29 ART
Tandou,
Disabling pruning is *not* the only way to accomplish this goal. What if
you the lab also stated "traffic for vlans not locally defined can not be
received over any trunk links throughout your VTP domain"
This task implies enabling VTP pruning. NOW how do you accomplish the goal
of "Although it does not have it locally assigned ensure that SW1 receives
traffic for VLAN 8 over port FA0/13"?
The answer is: switchport trunk pruning vlan remove 8
What the command is saying is: although I know the connected switch doesn't
have vlan 8 (I know this from VTP) I do NOT want to prune vlan 8 traffic. I
want to send vlan 8 broadcasts and multicasts across the trunk.
Try doing this: Create a trunk between Sw1 and Sw2 on F0/13. Then do this:
Sw1 - create these SVI's:
int vlan 100
int vlan 200
int vlan 300
Sw2 - create these SVI's:
int vlan 100
int vlan 200
int vlan 400
Notice Sw1 doesn't have vlan 400 and Sw2 doesn't have vlan 300. So, with VTP
pruning, Sw1 knows not to send vlan traffic (broadcasts and multicasts) for
vlan 300, since Sw2 doesn't have any ports in vlan 300. Now, do this
command: "sho int trunk"
Sw1#sho int trunk
Port Mode Encapsulation Status Native vlan
Fa0/13 on 802.1q trunking 1
Port Vlans allowed on trunk
Fa0/13 1-4094
Port Vlans allowed and active in management domain
Fa0/13 1,100,200,300,400 <--- VLAN 300 is allowed to go across the
trunk
Port Vlans in spanning tree forwarding state and not pruned
Fa0/13 1,100,200,400 <---- But VLAN 300 is pruned
Sw2#sho int trunk
Port Mode Encapsulation Status Native vlan
Fa0/13 on 802.1q trunking 1
Port Vlans allowed on trunk
Fa0/13 1-4094
Port Vlans allowed and active in management domain
Fa0/13 1,100,200,300,400 <--- VLAN 400 is allowed to go across the
trunk
Port Vlans in spanning tree forwarding state and not pruned
Fa0/13 1,100,200,300 <---- But VLAN 400 is pruned
Now, on Sw1 do this:
conf t
int f0/13
switchport trunk pruning vlan remove 300
end
Port Mode Encapsulation Status Native vlan
Fa0/13 on 802.1q trunking 1
Port Vlans allowed on trunk
Fa0/13 1-4094
Port Vlans allowed and active in management domain
Fa0/13 1,100,200,300,400 <--- VLAN 300 is allowed to go across the
trunk
Port Vlans in spanning tree forwarding state and not pruned
Fa0/13 1,100,200,300,400 <---- VLAN 300 is NOT pruned
That should help clear it up hopefully. Two more things. The best command to
help understand this in my opinion is "show int trunk mod 0". Try that out,
you'll like it. And the command "switchport trunk pruning vlan remove 300"
won't show up in the configs. Instead, this is what will show up:
"switchport trunk pruning vlan 2-299,301-1001". This helps confuse the issue
even more in my opinion.
hth,
Dave
This archive was generated by hypermail 2.1.4 : Thu Mar 01 2007 - 07:38:48 ART