1. 16-May-2001 1 NCAB VTP presentation Jeff Custard NCAR Network Engineering and Telecommunications Section

2. 16-May-2001 2 What is VTP? VLAN-Virtual Local Area Network VTP-VLAN Trunking Protocol A protocol Cisco created to maintain VLAN configuration consistency throughout the network

3. 16-May-2001 3 What does NETS do now? We currently do NOT implement VTP Manual entry for each added VLAN –The “edge switch” where the port needed the particular VLAN is –Plus each of the “core switches” Relies heavily on “manual entry consistency”

4. 16-May-2001 4 Why are we looking at VTP? VLAN configuration consistency Accurate VLAN tracking and monitoring Dynamic reporting of added VLANs “Plug-and-play” configuration when adding new VLANs

5. 16-May-2001 5 Why haven’t we used VTP before? Potential for distribution of “bad” network information –Configuration database has a revision number that is notification+1 (N+1) –A higher CRN indicates more current VLAN information –A higher CRN causes the stored VLAN information to be overwritten with the new info from the VTP update

6. 16-May-2001 6 VTP Operation “VTP Domain” defines VTP boundaries Each switch advertises the following on its trunk ports: –Management domain –Configuration revision number (CRN) –Known VLANs and their specific parameters

7. 16-May-2001 7 VTP Modes of operation Server Client Transparent

8. 16-May-2001 8 VTP Pruning Reduces unnecessary flooded traffic –Broadcast; Multicast; Unknown; Flooded unicast packets Doesn’t change STP characteristics Increases available bandwidth by restricting flooded traffic to only trunk links that must carry it Enabling VTP pruning allows pruning for the entire management domain

9. 16-May-2001 9 Flooded traffic WITHOUT VTP Pruning

10. 16-May-2001 10 Flooded traffic WITH VTP Pruning

11. 16-May-2001 11 For more information Cisco Press book "Building Cisco Multilayer Switched Networks" by Karen Webb These Cisco web pages: –Understanding and Configuring VLAN Trunk Protocol (VTP)Understanding and Configuring VLAN Trunk Protocol (VTP) –Configuring VTPConfiguring VTP

12. 16-May-2001 12 Questions?