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Trunking a 3550 to a 6513.... DTP, VTP, Prune-eligible....

Well I've done surfed Cisco on this for a while but still have more questions than answers. To begin with, I don't like VTP because of the potential to screw up the vlan database with a later revision(sequence?) number... So I don't use it in client server mode, only transparrent on the 6513 compressed backbone switch. Many times I will attach hosts to the 6513 by carving out a vlan on that box, which is running native mode. At this point, I want to attach a 3550 switch to one of these vlans. The switch will operate in the same vlan. These are the commands that may be used:

Commands to configure a range of interfaces into a vlan on the 6513:

Router# config t

Router(config)# vlan database

Router(vlan)# vtp transparent

Router(vlan)# exit

Router(config)# vlan 239

Router(config)# interface range fa9/2 - 7

Router(config-if-range)# switchport

Router(config-if-range)# switchport mode access

Router(config-if-range)# switchport access vlan 239

Router(config-if-range)# spanning-tree portfast

Commands to configure an interface into a trunk:

Router# config t

Router(config)# interface fa9/1

Router(config-if)# switchport

Router(config-if)# switchport mode trunk

Router(config-if)# switchport trunk encapsulation isl

Router(config-if)# spanning-tree uplink-fast

Are these commands viable? Will I need to prune in order to prevent this trunk from getting broadcasts from other vlans that are not on this interface? What does DTP buy me? Am I running it? If I specify transparrent mode, will VTP run and therefore will I be able to prune? thx


Re: Trunking a 3550 to a 6513.... DTP, VTP, Prune-eligible....

Yes, these commands are viable. You need to prune in order to prevent broadcasts from other VLANs that are not on your interface. But in VTP transparent mode, you should configure pruning MANUALLY on the interface. In your case DTP will work, if any of the switches sets to NULL VTP domain name.

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