ing VLANs Another way to route between VLANs is commonly known as the router-on-a-stick configuration. Instead of running a link from each VLAN to a router interface, you can run a single trunk from the switch to the router. All the VLANs will then pass over a single link, as shown in Figure 4-5. E 0/0 Trunk Port 8 Port 9 Port 10 Port 11 Port 12 Port 13 Port 14 Port 15 VLAN 20 VLAN 30 VLAN 40 VLAN 10 VLAN 10 VLAN 20 Port 0 Port 1 Port 2 Port 3 Port 4 Port 5 Port 6 Port 7 Figure 4-5. Router on a stick Deploying a router on a stick saves a lot of interfaces on both the switch and the router. The downside is that the trunk is only one link, and the total bandwidth available on that link is only 10 Mbps. In contrast, when each VLAN has its own link, each VLAN has 10 Mbps to itself. Also, don't forget that the router is passing traffic between VLANs, SO chances are each frame will be seen twice on the same link-once to get to the router, and once to get back to the destination VLAN. When I edited this chapter for the second edition, I briefly contemplated updating all the drawings to bring them more in line with currently common interface speeds. I decided against it because the last time I saw anyone doing router on a stick, the fastest switches only had 10M interfaces. It had nothing to do with me being too lazy to change the drawings. To be painfully accurate, running a trunk to a firewall and having the firewall perform default gateway functions for multiple VLANs employs the same principle, SO you could argue that I'm just too lazy after all. I would then counter with the fact that the latest switching technology from Cisco, the Nexus line, has done away with interface names that describe their speed, and instead names all Ethernet interfaces as "e slot/port". Therefore, I'm not lazy, but rather forward-thinking. Then I started writing the VoIP chapter where, lo and behold, I config- ured router on a stick in order to get my Voice-VLAN trunked to the router. Good thing I didn't pull the router-on-a-stick section.