ccna entry level

ccna entry level.VLAN ID MTU sizeVLAN NameFigure 13-3 Format of the VLAN Information Field in a VTP Subset Notification PacketWhen a request notice is sent to a switch in the same VTP domain, the switch responds by sending a summary notice followed by a subset notice. A request notice is sent when the following conditions occur: the VTP domain name changes, the switch receives a summary notice that contains a revision number larger than its own, a subset notice message is lost for some reason, or the switch is reset. The VTP Request Notice packet format is shown in Figure 13.4, where the starting value is the N+1st subset notice to be requested.13.1.4 VTP PruningThe case where VTP is not pruned is shown in Figure 13-5. When computer A in VLAN1 of Switch 1 sends a broadcast packet, the broadcast packet will be transmitted on the Trunk links of all switches, however, there are no computers in that VLAN on Switch3, Switch5, and Switch6 switches in the figure at all, thus wasting the Trunk link Bandwidth. You can enable the VTP pruning feature on the switch, and the situation after VTP is pruned is shown in Figure 13.6. There are no more broadcast packets for VLAN1 on the Trunk links on Switch2 and Switch3, Switch4 and Switch5, and Switch5 and Switch6 switches. The VTP pruning feature automatically calculates whichwhich VLANs the link should be pruned for packets, the administrator just needs to enable the feature.13.1.5 Introduction to DTPThe format of the VLAN information field in the VTP subset announcement packet is shown in Figure 13-3. The administrator can manually specify the links between the switches to form a Trunk,or let the switches automatically negotiate whether the linksFigure 13-5 VTP without pruning Figure 13-6 VTP with pruning