ol, this is simple. The keyword match in the redistribute command lets you match on route type: router eigrp 100 redistribute ospf 100 match internal network 20.20.20.0 0.0.0.255 default-metric 100000 100 255 1 1500 no auto-summary When redistributing other protocols, you must resort to route maps: router ospf 100 redistribute eigrp 100 route-map Only-Internal subnets network 10.10.10.0 0.0.0.255 area 0 default-metric 100 route-map Only-Internal permit 10 match route-type internal This solution solves both our problems. As the 50.50.50.0/24 route is an external route by nature of its original redistribution into R3, it will not be redistributed into OSPF. What once required many lines of code and multiple route maps has been accomplished with one keyword and a single two-line route map. Simple is good. Here is the final routing table from R2: R2# sho ip route [text removed] Gateway of last resort is not set 50.0.0.0/24 is subnetted, 1 subnets 50.50.50.0 [170/156160] via 20.20.20.3, 00:13:30, FastEtherneto/1 20.0.0.0/24 is subnetted, 1 subnets 20.20.20.0 is directly connected, FastEthernet0/1 10.0.0.0/24 is subnetted, 1 subnets 10.10.10.0 is directly connected, FastEtherneto/o As long as you keep things simple, tagging and filtering redistributed routes is easy. The more complicated the network is, the harder it is to keep all the redistributed net- works behaving properly. Additionally, a more complex network might not allow this last solution, because there might be valid external routes that need to be redistributed. Limiting Redistribution CHAPTER 12 Tunnels A tunnel is a means whereby a local device can communicate with a remote device as if the remote device were local as well. There are many types of tunnels. Virtual Pri- vate Networks (VPNs) are tunnels. Generic Routing Encapsulation (GRE) creates tunnels. Secure Shell (SSH) is also a form of tunnel, though different from the other two. Let's take a closer look at these three types: GRE tunnels are designed to allow remote networks to appear to be locally 